Columbia Acorn Trust

Prospectus
May 1, 2024
Columbia Acorn Family of Funds
Managed by Columbia Wanger Asset Management, LLC
Columbia 
  Thermostat FundSM
Class
Ticker Symbol
A
CTFAX
Advisor (Class Adv)
CTORX
C
CTFDX
Institutional (Class Inst)
COTZX
Class
Ticker Symbol
Institutional 2 (Class Inst2)
CQTRX
Institutional 3 (Class Inst3)
CYYYX
S (a)
As with all mutual funds, the Securities and Exchange Commission (SEC) has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.
(a)
Class S shares are not currently available for purchase.

Table of Contents
3
3
3
4
5
8
9
10
10
10
11
19
19
19
23
38
43
43
45
46
47
47
47
54
57
61
62
64
64
65
69
72
76
78
81
81
82
85
A-1
2

Columbia Thermostat FundSM
Summary of the Fund
Investment Objective
Columbia Thermostat FundSM (the Fund) seeks long-term capital appreciation.
Fees and Expenses of the Fund
This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information is available about these and other sales charge discounts and waivers from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 47 of the Fund’s prospectus, in Appendix A to the prospectus beginning on page A-1 and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.
Shareholder Fees (fees paid directly from your investment)
 
Class A
Class C
Classes Adv, Inst,
Inst2, Inst3,
and S
Maximum sales charge (load) imposed on purchases (as a % of offering price)
5.75
%
None
None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the
original purchase price or current net asset value)
1.00
%(a)
1.00
%(b)
None
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
 
Class A
Class Adv
Class C
Class Inst
Class Inst2
Class Inst3
Class S
Management fees
0.10
%
0.10
%
0.10
%
0.10
%
0.10
%
0.10
%
0.10
%
Distribution and/or service (12b-1) fees
0.25
%
0.00
%
1.00
%
0.00
%
0.00
%
0.00
%
0.00
%
Other expenses(c)
0.22
%
0.22
%
0.22
%
0.22
%
0.18
%
0.14
%
0.22
%
Acquired fund fees and expenses
0.36
%
0.36
%
0.36
%
0.36
%
0.36
%
0.36
%
0.36
%
Total annual Fund operating expenses(d)
0.93
%
0.68
%
1.68
%
0.68
%
0.64
%
0.60
%
0.68
%
Fee waivers and/or expense reimbursements(e)
(0.07
%)
(0.07
%)
(0.07
%)
(0.07
%)
(0.08
%)
(0.08
%)
(0.07
%)
Total annual Fund operating expenses after fee
waivers and/or expense reimbursements
0.86
%
0.61
%
1.61
%
0.61
%
0.56
%
0.52
%
0.61
%
(a)
This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)
This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.
(c)
Other expenses for Class S shares are based on estimated amounts for the Fund’s current fiscal year.
(d)
“Total annual Fund operating expenses” include acquired fund (Portfolio Fund) fees and expenses (expenses the Fund incurs indirectly through its investments in other funds) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include Portfolio Fund (acquired fund) fees and expenses.
(e)
Columbia Wanger Asset Management, LLC (the Investment Manager) has contractually agreed to waive fees and reimburse certain expenses of the Fund, through April 30, 2025, so that ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, including the Portfolio Funds) do not exceed the annual rates of 0.50% for Class A shares, 0.25% for Class Adv shares, 1.25% for Class C shares, 0.25% for Class Inst shares, 0.20% for Class Inst2 shares, 0.16% for Class Inst3 shares and 0.25% for Class S shares. This arrangement may only be amended or terminated with approval from the Fund's Board of Trustees and the Investment Manager. Any difference in these annual rates relative to the annual rates noted in the last row of the above table (e.g., net expense ratios) are due to applicable exclusions under the agreement. The fee waivers and/or expense reimbursements shown in the table also reflect the contractual agreement of the Fund's transfer agent, Columbia Management Investment Services Corp. (the Transfer Agent), to waive a portion of its fees through April 30, 2025, such that the Fund's transfer agency fees do not exceed the annual rates of 0.04% of the average daily net assets of Class Inst2 shares and 0.00% of the average daily net assets of Class Inst3 shares. This arrangement may be terminated at the sole discretion of the Fund's Board of Trustees.
Prospectus 2024
3

Columbia Thermostat FundSM
Summary of the Fund (continued)
Example
The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:
you invest $10,000 in the applicable class of Fund shares for the periods indicated,
your investment has a 5% return each year, and
the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.
Class C shares’ 10-year cost examples below reflect the Class C shares' 8-year conversion policy. 
Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire as indicated in the preceding table, they are only reflected in the 1 year example and the first year of the other examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:
 
1 year
3 years
5 years
10 years
Class A (whether or not shares are redeemed)
$658
$848
$1,054
$1,646
Class Adv (whether or not shares are redeemed)
$62
$211
$372
$840
Class C (assuming redemption of all shares at the end of the period)
$264
$523
$906
$1,782
Class C (assuming no redemption of shares)
$164
$523
$906
$1,782
Class Inst (whether or not shares are redeemed)
$62
$211
$372
$840
Class Inst2 (whether or not shares are redeemed)
$57
$197
$349
$791
Class Inst3 (whether or not shares are redeemed)
$53
$184
$327
$742
Class S (whether or not shares are redeemed)
$62
$211
$372
$840
Portfolio Turnover
The Fund will indirectly bear the expenses associated with portfolio turnover of the Portfolio Funds in which the Fund invests. Each Portfolio Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A Portfolio Fund’s higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when its shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 148% of the average value of its portfolio.
Principal Investment Strategies
The Fund is primarily managed as a fund that invests in other funds (i.e., a “fund-of-funds”) that seeks to achieve its investment objective by investing its assets among a selected group of underlying stock and bond mutual funds and exchanged-traded funds (ETFs) for which Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager) or its affiliates, including Columbia Management Investment Advisers, LLC (Columbia Management), serves as investment adviser or principal underwriter (the Portfolio Funds). Under normal circumstances, the Fund allocates at least 95% of its net assets (stock/bond assets) among the Portfolio Funds according to an asset allocation table based on the current level of the Standard & Poor’s (S&P) 500® Index.
Generally, the Fund’s allocation to stock funds increases as the S&P 500® Index declines and decreases as the S&P 500® Index rises. When the S&P 500® Index goes up in relation to trading range bands that are predetermined by the Investment Manager, the Fund sells a portion of its stock Portfolio Funds and invests more in the bond Portfolio Funds, and when the S&P 500® Index goes down in relation to the predetermined bands, the Fund increases its investment in the stock Portfolio Funds. Under normal circumstances, the Fund may invest up to 5% of net assets plus any cash received that day in cash, high quality short-term paper and government securities.
4
Prospectus 2024

Columbia Thermostat FundSM
Summary of the Fund (continued)
Although many asset allocation funds follow a basic approach of moving assets from stocks to bonds when the equity market goes up, and from bonds to stocks when the equity market goes down, some are run by investment managers who allocate fund assets by making subjective decisions based on complicated economic and financial models and complex graphs of market behavior. By contrast, the day-to-day investment decisions for the Fund are made according to a single predetermined allocation table. The temperature in your house is run by a single rule: your thermostat turns on the furnace if your house is too cold or turns on the air conditioner if your house is too warm. This Fund works the same way, so it is named Columbia Thermostat Fund.
Just as a thermostat may be set at different ranges for different seasons, the structure and allocation ranges of the Fund’s asset allocation table may be changed from time to time between two forms, based on the Investment Manager’s determination of whether it expects the equity market to be moving over the next year in a side-ways or non-directional pattern, which the Investment Manager terms an “expensive” market, or to be trending upward, which the Investment Manager terms a “normal” market. The Investment Manager’s process and methodology for determining whether the current market is “expensive” or “normal” and the structure of each form of allocation table are described in more detail in the Principal Investment Strategies section of the Fund's statutory prospectus. Such determination will be made on at least an annual basis and will be reflected in the asset allocation table disclosed in the Fund’s statutory prospectus. In general, the two different forms of allocation table are intended to maximize the capture of value under the two different sets of market conditions.
The Fund’s current form of asset allocation table, which is set forth in the Principal Investment Strategies section of the Fund's statutory prospectus, has been in place since the Fund’s inception, except for the period from May 1, 2020 through April 30, 2021. The current form of asset allocation table reflects the Investment Manager’s determination that the equity market is currently “expensive.” The “expensive” form of table may result in equity investment allocations as low as 10% or as high as 90% of Fund assets. The Investment Manager evaluates the appropriate form of asset allocation table and updates the S&P 500® Index trading range bands within the table at least annually. From May 1, 2020 through April 30, 2021, the form of asset allocation table in place for the Fund reflected the Investment Manager’s determination that the equity market was “normal.” With the “normal” form of table, the Fund’s equity investment allocations could be no less than 50% of Fund assets.
The Investment Manager chooses the Portfolio Funds to be generally consistent with the composition of the Fund’s primary stock and bond benchmarks and to allow the Fund to participate in strategies the Investment Manager believes can provide additional return due to active management.
The stock and bond Portfolio Funds that the Fund currently uses in its “fund-of-funds” structure, and the current target percentage for each Portfolio Fund within the stock or bond asset class, is set forth in the More Information – Principal Investment Strategies section of the statutory prospectus for the Fund. The Investment Manager may substitute or add additional Portfolio Funds at any time, including funds introduced after the date of this prospectus.
See the Portfolio Funds Summary section of the Fund’s statutory prospectus for information about the Portfolio Funds’ investment objectives and principal investment strategies. Each of the Portfolio Funds is managed by the Investment Manager or its affiliates. The Fund does not pay any sales load on its purchases of shares of the Portfolio Funds.
The Investment Manager will conduct the market state review at least annually prior to the annual updating of this prospectus, and may, in its discretion, assess the market state on an “emergency” basis and make any changes deemed necessary to reflect, for example, a very significant move in market levels or a structural change affecting the markets.
Any such “emergency” changes by the Investment Manager, which are expected to be infrequent, would be disclosed in this prospectus.
Principal Risks
An investment in the Fund involves risks, including general risks, as described below, relating to the Fund’s investment process and its “fund-of-funds” structure. An investment in the Fund also involves specific risks related to the individual Portfolio Funds, including but not limited to those in which it invests. These risks are listed below, which in the aggregate are considered principal risks of investing in the Fund. More information about the Portfolio
Prospectus 2024
5

Columbia Thermostat FundSM
Summary of the Fund (continued)
Funds, including their principal risks, is available in their prospectuses. This prospectus is not an offer for any of the Portfolio Funds. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and share price may go down. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Allocation Risk. The Investment Manager uses an asset allocation strategy in pursuit of its investment objective, there is a risk that the Fund's allocation among asset classes or investments will cause the Fund's shares to lose value or cause the Fund to underperform other funds with similar investment objectives and/or strategies, or that the investments themselves will not produce the returns expected.
Fund-of-Funds Risk. Determinations regarding asset classes or Portfolio Funds and the Fund’s allocations thereto may not successfully achieve the Fund’s investment objective, in whole or in part. The selected Portfolio Funds’ performance may be lower than the performance of the asset class they were selected to represent or may be lower than the performance of alternative Portfolio Funds that could have been selected to represent the asset class. The Fund also is exposed to the same risks as the Portfolio Funds in direct proportion to the allocation of its assets among the Portfolio Funds. By investing in a combination of Portfolio Funds, the Fund has exposure to the risks of many areas of the market. The ability of the Fund to realize its investment objective will depend, in large part, on the extent to which the Portfolio Funds realize their investment objectives. There is no guarantee that the Portfolio Funds will achieve their respective investment objectives. The performance of Portfolio Funds could be adversely affected if other entities that invest in the same Portfolio Funds make relatively large investments or redemptions in such Portfolio Funds. The Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each Portfolio Fund are shared by its investors, redemptions by other investors in a Portfolio Fund could result in decreased economies of scale and increased operating expenses for such fund. These transactions might also result in higher brokerage, tax or other costs for a Portfolio Fund. This risk may be particularly important when one investor owns a substantial portion of a Portfolio Fund. The Investment Manager may have potential conflicts of interest in selecting affiliated funds over unaffiliated funds for investment by the Fund, and may also face potential conflicts of interest in selecting affiliated funds, because the fees the Investment Manager receives from some Portfolio Funds may be higher than the fees paid by other Portfolio Funds. Columbia Thermostat Fund currently invests only in affiliated Portfolio Funds.
Market Risk. The Fund may incur losses due to declines in the value of one or more securities in which it invests. These declines may be due to factors affecting a particular issuer, or the result of, among other things, political, regulatory, market, economic or social developments affecting the relevant market(s) more generally. In addition, turbulence in financial markets and reduced liquidity in equity, credit and/or fixed income markets may negatively affect many issuers, which could adversely affect the Fund’s ability to price or value hard-to-value assets in thinly traded and closed markets and could cause significant redemptions and operational challenges. Global economies and financial markets are increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market. These risks may be magnified if certain events or developments adversely interrupt the global supply chain; in these and other circumstances, such risks might affect companies worldwide. As a result, local, regional or global events such as terrorism, war, other conflicts, natural disasters, disease/virus outbreaks and epidemics or other public health issues, recessions, depressions or other events – or the potential for such events – could have a significant negative impact on global economic and market conditions.
Frequent Trading Risk. The portfolio managers may actively and frequently trade investments in the Fund's portfolio to carry out its investment strategies. Frequent trading of investments increases the possibility that the Fund, as relevant, will realize taxable capital gains (including short-term capital gains, which are generally taxable to shareholders at higher rates than long-term capital gains for U.S. federal income tax purposes), which could reduce the Fund’s after-tax return. Frequent trading can also mean higher brokerage and other transaction costs, which could reduce the Fund's return. The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund’s performance.
6
Prospectus 2024

Columbia Thermostat FundSM
Summary of the Fund (continued)
The Fund is subject indirectly to the risks of the Portfolio Funds in which it invests. These risks are listed below. Please see the Portfolio Funds Summary and the More Information About the Fund sections of the Fund's statutory prospectus for information about the risks that apply to the Portfolio Funds.
Active Management Risk
Interest Rate Risk
Credit Risk
High-Yield Investments Risk
Value Securities Risk
Growth Securities Risk
Sector Risk (including Financial Services Sector Risk, and Information Technology Sector Risk)
Foreign Securities Risk
Loan Interests Risk
Emerging Market Securities Risk
Sovereign Debt Risk
Foreign Currency Risk
Issuer Risk (including Small- and Mid-Cap Stock Risk, and Large-Cap Stock Risk)
U.S. Government Obligations Risk
Derivatives Risk (including Futures Contracts Risk, Swaps Risk, Options Risk and Swaptions Risk)
Impairment of Collateral Risk
Convertible Securities Risk
Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk
Prepayment and Extension Risk
Reinvestment Risk
Depositary Receipts Risk
Changing Distribution Level Risk
Highly Leveraged Transactions Risk
Quantitative Models Risk
Rule 144A and Other Exempted Securities Risk
Counterparty Risk
Confidential Information Access Risk
Liquidity Risk
Mortgage- and Other Asset-Backed Securities Risk
Frequent Trading Risk
Leverage Risk
Stripped Mortgage-Backed Securities Risk
Valuation Risk
The Fund is subject indirectly to the following risks of Portfolio Funds seeking returns that correspond to a stated market index.
Passive Investment Risk
Prospectus 2024
7

Columbia Thermostat FundSM
Summary of the Fund (continued)
Index Fund Risk
Index Methodology Risk
Correlation/Tracking Error Risk
The Fund is subject indirectly to the following risks of Portfolio Funds that are exchange-traded funds seeking investment results that, before fees and expenses, closely correspond to the performance of a stated index.
Exchange-Traded Fund Risk
Secondary Market Trading Risk
Market Price Relative to NAV Risk
Authorized Participant Concentration Risk
Fund Shares Liquidity Risk
Early/Late Close/Trading Halt Risk
Performance Information
The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class S shares of the Fund had not commenced operations as of the date of this prospectus and has no performance information to report. The bar chart shows how the Fund’s Class Inst share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with those of two broad-based indexes: the S&P 500® Index, the Fund’s primary benchmark for equity securities, and the Bloomberg U.S. Aggregate Bond Index, the Fund’s primary benchmark for debt securities. The table below also compares the Fund’s returns with a secondary, custom index, the Blended Benchmark. The S&P 500® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks. The Bloomberg U.S. Aggregate Bond Index is a market value-weighted index that tracks the daily price, coupon, pay-downs, and total return performance of fixed-rate, publicly placed, dollar-denominated, and non-convertible investment grade debt issues with at least $250 million par amount outstanding and with at least one year to final maturity. The Blended Benchmark was established by the Investment Manager to show how the Fund’s performance compares to an equally weighted custom composite of the Fund’s primary equity and primary debt benchmarks, the S&P 500® Index and the Bloomberg U.S. Aggregate Bond Index, respectively. The percentage of the Fund’s assets allocated to underlying stock and bond Portfolio Funds will vary, and accordingly the composition of the Fund’s portfolio will not always reflect the composition of the Blended Benchmark.
Any share class, such as Class S shares, without performance to report, would have annual returns substantially similar to Class Inst shares. Except for differences in fees and expenses, all share classes of the Fund would have substantially similar annual returns because all share classes of the Fund invest in the same portfolio of securities.
The after-tax returns shown in the Average Annual Total Returns table below are calculated using the highest historical individual U.S. federal marginal income tax rates in effect during the period indicated in the table and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-advantaged accounts such as 401(k) plans or Individual Retirement Accounts (IRAs). The after-tax returns are shown only for Class Inst shares and will vary for other share classes.
The Fund’s performance prior to May 2018 reflects returns achieved following a principal investment strategy with a single form of asset allocation table. While the Fund now follows a principal investment strategy with two potential forms of asset allocation tables, as described above in the Principal Investment Strategies section, the form of the Fund’s currently effective asset allocation table was in place from the Fund’s inception in 2002 through April 30, 2020. The Fund's performance prior to May 1, 2020 and after April 30, 2021 reflects the current form of allocation table. The Fund’s performance from May 1, 2020 through April 30, 2021 reflects a different form of asset allocation table.
8
Prospectus 2024

Columbia Thermostat FundSM
Summary of the Fund (continued)
The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting columbiathreadneedleus.com.
Year by Year Total Return (%)
as of December 31 Each Year*
Best and Worst Quarterly Returns
During the Period Shown in the Bar Chart
Best
2nd Quarter 2020
13.30%
Worst
2nd Quarter 2022
-6.82%
*
Year to Date return as of March 31, 2024: 0.20%
Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2023)
 
Share Class
Inception Date
1 Year
5 Years
10 Years
Class Inst
09/25/2002
 
 
 
returns before taxes
 
11.66%
9.08%
6.11%
returns after taxes on distributions
 
10.48%
6.89%
4.28%
returns after taxes on distributions and sale of Fund shares
 
6.95%
6.51%
4.20%
Class A returns before taxes
03/03/2003
4.95%
7.55%
5.22%
Class Adv returns before taxes
11/08/2012
11.64%
9.09%
6.12%
Class C returns before taxes
03/03/2003
9.52%
8.00%
5.06%
Class Inst2 returns before taxes
11/08/2012
11.67%
9.13%
6.15%
Class Inst3 returns before taxes
11/08/2012
11.73%
9.17%
6.19%
Blended Benchmark (Secondary Benchmark; an equally weighted custom
composite of the Fund's primary benchmarks for equity and debt securities,
established by the Investment Manager; reflects no deductions for fees,
expenses or taxes)
 
15.58%
8.53%
7.08%
S&P 500® Index (Primary Equity Benchmark; reflects no deductions for fees,
expenses or taxes)
 
26.29%
15.69%
12.03%
Bloomberg U.S. Aggregate Bond Index (Primary Debt Benchmark; reflects no
deductions for fees, expenses or taxes)
 
5.53%
1.10%
1.81%
Fund Management
Investment Manager: Columbia Wanger Asset Management, LLC
Portfolio Management
Title
Role with Fund
Service with the Fund Since
Alex M. Rivas
Portfolio Manager of Columbia
Management and Vice President of the
Investment Manager
Portfolio Manager
since 2022
2018
Corey Lorenzen, CFA
Portfolio Manager of Columbia
Management and Vice President of the
Investment Manager
Portfolio Manager
since 2023
2023
Prospectus 2024
9

Columbia Thermostat FundSM
Summary of the Fund (continued)
Purchase and Sale of Fund Shares
You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:
Online
Regular Mail
Express Mail
By Telephone
columbiathreadneedleus.com/investor/
Columbia Management
Investment Services Corp.
P.O. Box 219104
Kansas City, MO 64121-9104
Columbia Management
Investment Services Corp.
c/o SS&C GIDS, Inc.
430 W 7th Street, Suite 219104
Kansas City, MO 64105-1407
800.422.3737
You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. If you maintain your account with a broker-dealer or other financial intermediary, you must contact that financial intermediary to buy, sell or exchange shares of the Fund through your account with the intermediary.
The minimum initial investment amounts for the share classes offered by the Fund are shown below:
Minimum Initial Investment
Class
Category of eligible
account
For accounts other than
Systematic Investment
Plan accounts (as described in the Fund’s Prospectus)
For Systematic Investment
Plan accounts
Classes A & C
All accounts other than
IRAs
$2,000
$100
IRAs
$1,000
$100
Classes Adv & Inst
All eligible accounts
$0, $1,000 or $2,000
depending upon the category
of eligible investor
$100
Class Inst2
All eligible accounts
None
N/A
Class Inst3
All eligible accounts
$0, $1,000, $2,000
or $1 million depending
upon the category
of eligible investor
$100 (for certain
eligible investors)
More information about these minimums can be found in the Buying, Selling and Exchanging Shares - Buying Shares section of the prospectus. There is no minimum additional investment for any share class.
Tax Information
The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are investing through a tax-advantaged account, such as a 401(k) plan or an IRA. The use of a fund-of-funds structure could affect the timing, amount and character of distributions to you and therefore may increase the amount of taxes payable by you. If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.
Payments to Broker-Dealers and Other Financial Intermediaries
If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, the Distributor and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. These potential conflicts of interest may be heightened with respect to broker-dealers owned by Ameriprise Financial, Inc. (Ameriprise Financial) and/or its affiliates. Ask your financial advisor or visit your financial intermediary's website for more information.
10
Prospectus 2024

Columbia Thermostat FundSM
Portfolio Funds Summary
The following provides a brief overview of the investment objectives and principal investments of the Portfolio Funds in which the Fund invests. The Fund’s NAV is calculated based on the NAVs of the Portfolio Funds.
You'll find more detailed information about each Portfolio Fund’s investment strategies and risks in its prospectus and SAI. Descriptions of the principal risks listed below for each of the Portfolio Funds are included in the More Information About the Fund section of this prospectus. The Portfolio Funds’ prospectuses also discuss the circumstances under which the Portfolio Funds use fair value pricing and the effects thereof. Refer to columbiathreadneedle.com/us or contact your financial advisor for details.
Columbia Contrarian Core Fund
The fund seeks total return, consisting of long-term capital appreciation and current income.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks, and at least 80% of its net assets in equity securities of U.S. companies that have large market capitalizations (generally over $2 billion) that the fund’s investment adviser believes are undervalued and have the potential for long-term growth and current income.
The fund may invest up to 20% of its net assets in foreign securities directly or indirectly through depositary receipts.
The fund may at times emphasize one or more sectors in selecting its investments, including the information technology sector.
The principal risks of the fund include Active Management Risk, Changing Distribution Level Risk, Depositary Receipts Risk, Foreign Securities Risk, Growth Securities Risk, Issuer Risk (including Large-Cap Stock Risk), Market Risk, Sector Risk (including Information Technology sector), and Value Securities Risk.
Columbia Corporate Income Fund
The fund seeks total return, consisting primarily of current income and secondarily of capital appreciation.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in debt securities issued by corporate and other non-governmental issuers, including dollar-denominated debt securities issued by foreign companies. The fund also invests at least 60% of total assets in securities that, at the time of purchase, are investment grade securities or in unrated securities determined to be of comparable quality. The fund may invest up to 25% of its total assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high-yield” investments or “junk” bonds). Under normal circumstances, the fund’s average effective duration will be between three and ten years.
The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis.
The fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to liquidity determinations and certain regulatory restrictions.
The fund may invest in U.S. Government obligations, asset-backed securities and mortgage-backed securities.
The principal risks of the fund include Active Management Risk, Changing Distribution Level Risk, Counterparty Risk, Credit Risk, Foreign Securities Risk, High-Yield Investments Risk, Interest Rate Risk, Issuer Risk, Liquidity Risk, Market Risk, Mortgage- and Other Asset-Backed Securities Risk, Prepayment and Extension Risk, Reinvestment Risk, Rule 144A and Other Exempted Securities Risk, and U.S. Government Obligations Risk.
Columbia Diversified Fixed Income Allocation ETF
The fund seeks investment results that, before fees and expenses, closely correspond to the performance of the Beta Advantage® Multi-Sector Bond Index.
The fund is an exchange-traded fund that seeks to track the performance of the Beta Advantage® Multi-Sector Bond Index. The fund invests at least 80% of its assets in securities within the Beta Advantage® Multi-Sector Bond Index or in securities, such as depositary receipts and “to-be-announced” (TBA) securities, that the fund’s investment adviser determines have economic characteristics that are substantially the same as the economic
Prospectus 2024
11

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
characteristics of the securities within the Beta Advantage® Multi-Sector Bond Index. For purposes of this policy, the fund invests at least 80% of its net assets (plus borrowings for investment purposes) in fixed income (or debt) securities. In addition, the fund may invest in cash, cash equivalents and money market instruments, such as repurchase agreements and money market funds (including money market funds advised by affiliates of the Investment Manager), that the fund’s investment adviser believes will help the fund track the performance of the Beta Advantage® Multi-Sector Bond Index.
The Beta Advantage® Multi-Sector Bond Index is owned and calculated by Bloomberg Index Services Limited (Bloomberg), which is not affiliated with the fund or the Investment Manager and its affiliates. The Beta Advantage® Multi-Sector Bond Index was developed by Columbia Management working with Bloomberg.
Beta Advantage® Multi-Sector Approach to Debt Market Investing. The Beta Advantage® Multi-Sector Bond Index reflects a rules-based multi-sector strategic beta approach to measuring the performance of the debt market through representation of six segments of the debt market (U.S. Treasury securities, global ex-U.S. treasury securities, U.S. agency mortgage-backed securities, U.S. corporate investment grade bonds, U.S. corporate high yield bonds, and emerging markets sovereign and quasi-sovereign debt) in the Beta Advantage® Multi-Sector Bond Index, each focused on yield, quality, and liquidity of the particular segment.
The fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions.
The Beta Advantage® Multi-Sector Bond Index is reconstituted and rebalanced monthly typically on the last business day of each month. The fund will typically experience portfolio turnover in connection with index reconstitution and rebalancing. The fund's investment adviser utilizes a "representative sampling" strategy whereby the fund invests in only some of the component securities of the Beta Advantage® Multi-Sector Bond Index that, collectively, are believed by the fund's investment adviser to generally reflect the same risk and return characteristics of the Beta Advantage® Multi-Sector Bond Index. As such, the fund may not track the Beta Advantage® Multi-Sector Bond Index with the same degree of accuracy as would a fund replicating (or investing in) the entire Beta Advantage® Multi-Sector Bond Index. Through its representative sampling investment technique, the fund expects to typically hold 500-800 holdings, which is a subset of the total number of holdings in the Beta Advantage® Multi-Sector Bond Index, which, as of January 31, 2024, had 1,094 holdings. There may be instances in which the fund may overweight (or underweight) a holding in the Beta Advantage® Multi-Sector Bond Index, purchase (or sell) instruments not in the Beta Advantage® Multi-Sector Bond Index as a substitute for one or more securities in the Beta Advantage® Multi-Sector Bond Index or utilize various combinations of other available investment techniques in seeking to track the performance of the Beta Advantage® Multi-Sector Bond Index. The fund may hold less than or more than the typical number of holdings in the range stated above, with the fund portfolio management team applying investment experience and insight with the goal of seeking investment results that closely correspond to the performance of the Beta Advantage® Multi-Sector Bond Index.
The fund may sell securities or other holdings that are represented in the Beta Advantage® Multi-Sector Bond Index or purchase securities or make other investments that are not yet represented in the Beta Advantage® Multi-Sector Bond Index in anticipation of their removal from or addition to the Beta Advantage® Multi-Sector Bond Index. The fund's investment adviser does not invest the fund's assets based on its view of the investment merits of a particular security or company, neither does it conduct fundamental investment research or analysis, nor seek to forecast or otherwise consider market movements, conditions or trends in managing the fund's assets. The fund pursues its investment objective of correlating performance with the Beta Advantage® Multi-Sector Bond Index regardless of market conditions and does not take defensive positions.
To the extent the Beta Advantage® Multi-Sector Bond Index is concentrated in a particular segment, sector or industry, the fund will be concentrated in that segment, sector or industry.
The principal risks of the fund include Authorized Participant Concentration Risk, Changing Distribution Level Risk, Correlation/Tracking Error Risk, Counterparty Risk, Credit Risk, Depositary Receipts Risk, Early/Late Close/Trading Halt Risk, Emerging Market Securities Risk, Foreign Currency Risk, Foreign Securities Risk, Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk, Frequent Trading Risk, Fund
12
Prospectus 2024

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
Shares Liquidity Risk, High-Yield Investments Risk, Index Methodology Risk, Interest Rate Risk, Issuer Risk, Liquidity Risk, Market Price Relative to NAV Risk, Market Risk, Mortgage Backed Securities Risk, Passive Investment Risk, Portfolio Turnover Risk, Prepayment and Extension Risk, Reinvestment Risk, Rule 144A and Other Exempted Securities Risk, Secondary Market Trading Risk, Sector Risk, Sovereign Debt Risk, U.S. Government Obligations Risk, and Valuation Risk.
Columbia High Yield Bond Fund
The fund seeks to provide shareholders with high current income as its primary objective and, as its secondary objective, capital growth.
Under normal market conditions, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in high-yield debt instruments (commonly referred to as “junk” bonds or securities). These high yield debt instruments include corporate debt securities as well as floating rate loans rated below investment grade by nationally recognized statistical rating organizations, or if unrated, determined to be of comparable quality.
The fund may invest up to 25% of its net assets in debt instruments of foreign issuers.
Corporate debt instruments in which the fund invests are typically unsecured, with a fixed-rate of interest, and are usually issued by companies or similar entities to provide financing for their operations, or other activities. Floating rate loans, which are another form of financing, are typically secured, with interest rates that adjust or “float” periodically (normally on a daily, monthly, quarterly or semiannual basis by reference to a base lending rate, plus a premium).
The fund may invest in debt instruments of any maturity and does not seek to maintain a particular dollar-weighted average maturity. Because the fund emphasizes high-yield investments, more emphasis is put on credit risk by the portfolio managers in selecting investments than either maturity or duration.
The fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions.
The principal risks of the fund include Active Management Risk, Changing Distribution Level Risk, Confidential Information Access Risk, Counterparty Risk, Credit Risk, Foreign Securities Risk, High-Yield Investments Risk, Highly Leveraged Transactions Risk, Impairment of Collateral Risk, Interest Rate Risk, Issuer Risk, Liquidity Risk, Loan Interests Risk, Market Risk, Prepayment and Extension Risk, Reinvestment Risk, and Rule 144A and Other Exempted Securities Risk,
Columbia Large Cap Enhanced Core Fund
The fund seeks total return before fees and expenses that exceeds the total return of the S&P 500® Index.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks that comprise the S&P 500® Index, convertible securities that are convertible into stocks included in the S&P 500® Index, and derivatives whose returns are closely equivalent to the returns of the S&P 500® Index or its components.
The fund generally holds fewer stocks than the S&P 500® Index and may hold securities that are not in the S&P 500® Index.
The fund’s investment adviser attempts to maintain a portfolio that generally matches the risk characteristics of the S&P 500® Index, but it will vary the number and percentages of the fund’s holdings in attempting to provide higher returns than the S&P 500® Index and to reduce the potential of underperforming the S&P 500® Index over time.
The fund at times emphasize one or more economic sectors in selecting its investments, including the information technology sector.
The fund’s portfolio managers use quantitative analysis to evaluate the relative attractiveness of potential investments.
Prospectus 2024
13

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
The fund may invest in derivatives, such as futures (including equity futures and index futures), for cash equitization and investment flexibility.
The principal risks of the fund include Active Management Risk, Convertible Securities Risk, Counterparty Risk, Derivatives Risk, Derivatives Risk – Futures Contracts Risk, Issuer Risk (including Large-Cap Stock Risk), Market Risk, Quantitative Model Risk, and Sector Risk (including the Information Technology sector).
Columbia Large Cap Growth Fund
The fund seeks long-term capital appreciation.
Under normal market conditions, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in equity securities of large-capitalization companies, primarily common stocks and securities that can be converted into common stocks. These companies have market capitalizations in the range of companies in the Russell 1000 Growth Index at the time of purchase (between $451.6 million and $2.7 trillion as of October 31, 2023). The market capitalization range and composition of companies in the Russell 1000 Growth Index are subject to change. The fund invests primarily in common stocks of companies that its investment manager believes have long-term competitive advantages and have the potential for sustainable, above-average, revenue and earnings growth. The fund may at times emphasize one or more sectors in selecting its investments, including the information technology sector.
The fund may invest up to 20% of its total assets in foreign securities. The fund may invest directly in foreign securities or indirectly through depositary receipts.
The principal risks of the fund include Active Management Risk, Convertible Securities Risk, Depositary Receipts Risk, Foreign Securities Risk, Growth Securities Risk, Issuer Risk (including Large-Cap Stock Risk), Market Risk, and Sector Risk (including the Information Technology Sector).
Columbia Large Cap Index Fund
The fund seeks total return before fees and expenses that corresponds to the total return of the S&P 500® Index.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks that comprise the S&P 500® Index.
The fund’s investment adviser attempts to allocate the fund’s assets among common stocks in approximately the same weightings as the S&P 500® Index. This is referred to as a passive or indexing approach to investing. The fund’s portfolio will typically emphasize those economic sectors emphasized by the S&P 500® Index, such as the information technology sector.
The fund may invest in derivatives, such as futures (including equity index futures), for cash equitization purposes.
The fund attempts to achieve at least a 95% correlation between the performance of the S&P 500® Index and the fund’s investment results, before fees and expenses.
The fund may buy shares of Ameriprise Financial, Inc., an affiliate of the Investment Manager, which is currently included in the S&P 500® Index, subject to certain restrictions.
The principal risks of the fund include Correlation/Tracking Error Risk, Derivatives Risk, Derivatives Risk – Futures Contracts Risk, Issuer Risk (including Large-Cap Stock Risk), Market Risk, Passive Investment Risk, and Sector Risk (including the Information Technology sector).
Columbia Quality Income Fund
The fund seeks to provide shareholders with current income as its primary objective and, as its secondary objective, preservation of capital.
Under normal market conditions, at least 80% of the fund’s net assets (including the amount of any borrowings for investment purposes) are invested in mortgage-related securities, which include those that are either issued or guaranteed as to principal and interest by the U.S. Government, its agencies, authorities or instrumentalities (U.S. Government Securities), those issued by non-U.S. governments, as well as residential and commercial
14
Prospectus 2024

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
mortgage-backed securities issued by non-governmental entities. Mortgage-related securities that either are issued or guaranteed as to principal and interest by the U.S. Government, its agencies, authorities or instrumentalities include Government National Mortgage Association (GNMA or Ginnie Mae) mortgage-backed bonds, which are backed by the full faith and credit of the U.S. Government; and Federal National Mortgage Association (FNMA or Fannie Mae) and Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac) mortgage backed bonds. FNMA and FHLMC are chartered or sponsored by Acts of Congress; however, their securities are neither issued nor guaranteed by the U.S. Treasury or backed by the full faith and credit of the U.S. Government.
The fund may invest in stripped mortgage-backed securities such as interest-only (IO) and principal-only (PO) securities.
Under normal circumstances, the Fund invests at least 60% of its net assets in mortgage-related securities that are U.S. Government Securities and at least 80% of its net assets in securities rated investment grade by a nationally recognized statistical rating organization or, if unrated, determined to be of comparable quality. The Fund may invest up to 20% of its net assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as "high-yield” investments or “junk” bonds).
The fund may invest in debt instruments of any maturity and does not seek to maintain a particular dollar-weighted average maturity.
The fund may invest in privately placed securities and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933 subject to liquidity determinations and certain regulatory restrictions.
The fund may invest in derivatives, such as futures (including interest rate futures) to manage interest rate exposure, swaps (including interest rate swaps) to manage credit and interest rate exposure and options on swaps (commonly known as swaptions) to manage interest rate exposure. The fund’s use of derivatives may result in leverage (market exposure in excess of the fund’s assets). The fund may hold a significant amount of cash, money market instruments (which may include investments in one or more affiliated or unaffiliated money market funds or similar vehicles), other high-quality, short-term investments, or other liquid assets to meet its segregation obligations as a result of its investments in derivatives.
The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.
The fund’s investment strategy may involve the frequent trading of portfolio securities.
The principal risks of the fund include Active Management Risk, Changing Distribution Level Risk, Counterparty Risk, Credit Risk, Derivatives Risk, Derivatives Risk – Futures Contracts Risk, Derivatives Risk – Options Risk, Derivatives Risk – Swaps Risk, Derivatives Risk – Swaptions Risk, Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk, Frequent Trading Risk, High-Yield Investments Risk, Interest Rate Risk, Leverage Risk, Liquidity Risk, Market Risk, Mortgage- and Other Asset-Backed Securities Risk, Prepayment and Extension Risk, Reinvestment Risk, Rule 144A and Other Exempted Securities Risk, Sovereign Debt Risk, Stripped Mortgage-Backed Securities Risk, and U.S. Government Obligations Risk.
Columbia Research Enhanced Core ETF
The fund seeks investment results that, before fees and expenses, closely correspond to the performance of the Beta Advantage® Research Enhanced U.S. Equity Index.
The fund is an exchange-traded fund that seeks to replicate the performance of the Beta Advantage® Research Enhanced U.S. Equity Index. The fund invests at least 80% of its assets in the securities of the Beta Advantage® Research Enhanced U.S. Equity Index. The Beta Advantage® Research Enhanced U.S. Equity Index reflects a rules-based strategic beta approach to investing in the companies that comprise the Russell 1000® Index,
Prospectus 2024
15

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
designed to achieve stronger total return when compared to the Russell 1000® Index, which is a broad measure of the performance of U.S. large- and mid-cap growth and value companies. The Beta Advantage® Research Enhanced U.S. Equity Index, like the Russell 1000® Index, and therefore the Fund, typically holds only common stocks.
The Beta Advantage® Research Enhanced U.S. Equity Index was developed and is sponsored and administered by the fund’s investment adviser, Columbia Management. The Index is calculated and maintained by FTSE Russell.
The Beta Advantage® Research Enhanced U.S. Equity Index is comprised of a subset of the companies within the Russell 1000® Index. With a starting point of the Russell 1000® Index, the Beta Advantage® Research Enhanced U.S. Equity Index was designed to reflect the performance of U.S. large- and mid-cap growth and value companies through the application of a rules-based methodology, that takes into account quality, value and company catalyst factors. The methodology typically results in approximately 325-400 holdings, but this range can fluctuate because the Beta Advantage® Research Enhanced U.S. Equity Index has no constraints on number of holdings.
The number of securities in each sector and the Beta Advantage® Research Enhanced U.S. Equity Index as a whole may change over time. The Beta Advantage® Research Enhanced U.S. Equity Index is reconstituted and rebalanced semi-annually in June and December.
The fund uses a replication strategy to track the performance of the Beta Advantage® Research Enhanced U.S. Equity Index, whereby the fund invests in or has investment exposure to substantially all the component securities of the Beta Advantage® Research Enhanced U.S. Equity Index in approximately the same proportions as in the Beta Advantage® Research Enhanced U.S. Equity Index. However, under various circumstances, including circumstances under which it may not be possible or practicable to purchase all of the securities in the index, or in the same weightings, the fund may purchase or have investment exposure to a sample (large or small quantity) of the securities in the index in proportions expected to replicate generally the performance of the index as a whole. There may also be instances in which the fund may overweight (or underweight) a holding in the Beta Advantage® Research Enhanced U.S. Equity Index, purchase (or sell) instruments not in the index as a substitute for one or more securities in the index or utilize various combinations of other available investment techniques in seeking to replicate the performance of the index.
The fund may sell securities or other holdings that are represented in the Beta Advantage® Research Enhanced U.S. Equity Index or purchase securities or make other investments that are not yet represented in the index in anticipation of their removal from or addition to the index.
Columbia Management does not provide day-to-day management of the fund’s assets based on its view of the investment merits of a security or company, nor does it conduct fundamental investment research or analysis, or seek to forecast or otherwise consider market movements, conditions or trends in the day-to-day management of the fund’s assets. The fund pursues its investment objective of correlating performance with the Beta Advantage® Research Enhanced U.S. Equity Index regardless of market conditions and does not take defensive positions.
The methodology applied to select holdings in the Beta Advantage® Research Enhanced U.S. Equity Index and weightings does not set limits on sector or industry exposures. To the extent the Beta Advantage® Research Enhanced U.S. Equity Index is concentrated in a sector or industry, the fund will necessarily be concentrated in that sector or industry.
The fund may invest up to 20% of its assets in other securities or instruments not included within the Index that Columbia Management believes will help the fund track the Beta Advantage® Research Enhanced U.S. Equity Index.
The principal risks of the fund include Authorized Participant Concentration Risk, Correlation/Tracking Error Risk, Early/Late Close/Trading Halt Risk, Fund Shares Liquidity Risk, Growth Securities Risk, Index Methodology Risk,
16
Prospectus 2024

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
Issuer Risk (including Mid-Cap Stock Risk and Large-Cap Stock Risk), Market Price Relative to NAV Risk, Market Risk, Passive Investment Risk, Quantitative Models Risk, Secondary Market Trading Risk, Sector Risk (including the Information Technology sector), and Value Securities Risk.
Columbia Small Cap Index Fund
The fund seeks total return before fees and expenses that corresponds to the total return of the Standard & Poor’s (S&P) SmallCap 600® Index.
Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks that comprise the S&P SmallCap 600 Index (the Index).
The Fund may invest in derivatives, such as futures (including equity index futures), for cash equitization purposes.
Different common stocks have different weightings in the Index, depending on the amount of stock outstanding and the stock’s current price. In seeking to match the performance of the Index, Columbia Management attempts to allocate the Fund’s assets among common stocks in approximately the same weightings as the Index. This is referred to as a passive or indexing approach to investing. As a result of the Fund’s indexing approach to investing, the Fund will typically emphasize within the portfolio those economic sectors emphasized by the Index, such as the financial services sector.
The Fund attempts to achieve at least a 95% correlation between the performance of the Index and the Fund’s investment results, before fees and expenses.
The principal risks of the fund include Correlation/Tracking Error Risk, Derivatives Risk, Derivatives Risk – Futures Contracts Risk, Issuer Risk (including Small-Cap Stock Risk), Market Risk, Passive Investment Risk, and Sector Risk (including the Financial Services Sector).
Columbia Total Return Bond Fund
The fund seeks total return, consisting of current income and capital appreciation.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in bonds, notes and other debt instruments, including derivatives relating to such investments.
The fund may invest up to 35% of its net assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high-yield” investments or “junk” bonds).
The fund may invest in debt instruments issued by U.S. and non-U.S. governments, their agencies, authorities or instrumentalities, U.S. and non-U.S. corporate or other non-governmental entities, as well as mortgage- and other asset-backed securities.
The fund generally expects to maintain an effective duration of +/- 2 years relative to the Bloomberg U.S. Aggregate Bond Index.
The fund may invest in derivatives, such as futures (including interest rate futures) and swaps (including credit default swaps, credit default swap indexes, and interest rate swaps) for hedging and investment purposes, and to manage interest rate and/or credit exposure of the fund.
The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.
The fund’s investments in mortgage-related securities include investments in stripped mortgage-backed securities such as interest-only (IO) and principal-only (PO) securities.
The fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions.
Prospectus 2024
17

Columbia Thermostat FundSM
Portfolio Funds Summary (continued)
The fund’s investment strategy may involve the frequent trading of portfolio securities.
The principal risks of the fund include Active Management Risk, Changing Distribution Level Risk, Counterparty Risk, Credit Risk, Derivatives Risk, Derivatives Risk – Futures Contracts Risk, Derivatives Risk – Swaps Risk, Foreign Securities Risk, Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk, Frequent Trading Risk, High-Yield Investments Risk, Interest Rate Risk, Issuer Risk, Leverage Risk, Liquidity Risk, Market Risk, Mortgage- and Other Asset-Backed Securities Risk, Prepayment and Extension Risk, Reinvestment Risk, Rule 144A and Other Exempted Securities Risk, Sovereign Debt Risk, Stripped Mortgage-Backed Securities Risk, and U.S. Government Obligations Risk.
Columbia U.S. Treasury Index Fund
The fund seeks total return that corresponds to the total return of the FTSE USBIG Treasury Index, before fees and expenses.
Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in securities that comprise the FTSE USBIG Treasury Index, which is an unmanaged index composed of U.S. Treasury notes and bonds with remaining maturities of at least one year and outstanding principal of at least $5 billion and which are included in the FTSE U.S. Broad Investment-Grade Bond Index.
Different securities have different weightings in the FTSE USBIG Treasury Index and are weighted by market value; that is, the price per bond or note multiplied by the number of bonds or notes outstanding.
In seeking to match the performance of the FTSE USBIG Treasury Index, before fees and expenses, the fund’s investment adviser attempts to allocate the fund’s assets among securities in the FTSE USBIG Treasury Index. The fund will not hold all of the securities in the FTSE USBIG Treasury Index.
The principal risks of the fund include Correlation/Tracking Error Risk, Credit Risk, Interest Rate Risk, Market Risk, Passive Investment Risk, and U.S. Government Obligations Risk.
18
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund
Investment Objective
Columbia Thermostat FundSM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.
Principal Investment Strategies
The Fund is primarily managed as a fund that invests in other funds (i.e., a “fund-of-funds”) that seeks to achieve its investment objective by investing its assets among a selected group of underlying stock and bond mutual funds and exchanged-traded funds (ETFs) for which Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager) or its affiliates, including Columbia Management Investment Advisers, LLC (Columbia Management), serves as investment adviser or principal underwriter (the Portfolio Funds). Under normal circumstances, the Fund allocates at least 95% of its net assets (stock/bond assets) among the Portfolio Funds according to an asset allocation table based on the current level of the Standard & Poor’s (S&P) 500® Index.
Generally, the Fund’s allocation to stock funds increases as the S&P 500® Index declines and decreases as the S&P 500® Index rises. When the S&P 500® Index goes up in relation to trading range bands that are predetermined by the Investment Manager, the Fund sells a portion of its stock Portfolio Funds and invests more in the bond Portfolio Funds, and when the S&P 500® Index goes down in relation to the predetermined bands, the Fund increases its investment in the stock Portfolio Funds. Under normal circumstances, the Fund may invest up to 5% of net assets plus any cash received that day in cash, high quality short-term paper and government securities.
Although many asset allocation funds follow a basic approach of moving assets from stocks to bonds when the equity market goes up, and from bonds to stocks when the equity market goes down, some are run by investment managers who allocate fund assets by making subjective decisions based on complicated economic and financial models and complex graphs of market behavior. By contrast, the day-to-day investment decisions for the Fund are made according to a single predetermined allocation tableset forth below. The temperature in your house is run by a single rule: your thermostat turns on the furnace if your house is too cold or turns on the air conditioner if your house is too warm. This Fund works the same way, so it is named Columbia Thermostat Fund.
Just as a thermostat may be set at different ranges for different seasons, the structure and allocation ranges of the Fund’s asset allocation table may be changed from time to time between two forms, based on the Investment Manager’s determination of whether it expects the equity market to be moving over the next year in a side-ways or non-directional pattern, which the Investment Manager terms an “expensive” market, or to be trending upward, which the Investment Manager terms a “normal” market. The Investment Manager’s process and methodology for determining whether the current market is “expensive” or “normal” and the structure of each form of allocation table are described in more detail below under Determination of Current Market State. Such determination will be made on at least an annual basis and will be reflected in the asset allocation table disclosed in this prospectus. In general, the two different forms of allocation table are intended to maximize the capture of value under the two different sets of market conditions.
The Fund’s current form of asset allocation table, which is set forth below, has been in place since the Fund’s inception, except for the period from May 1, 2020 through April 30, 2021. The current form of asset allocation table reflects the Investment Manager’s determination that the equity market is currently “expensive.” The “expensive” form of table may result in equity investment allocations as low as 10% or as high as 90% of Fund assets. The Investment Manager evaluates the appropriate form of asset allocation table and updates the S&P 500® Index trading range bands within the table at least annually. From May 1, 2020 through April 30, 2021, the form of asset allocation table in place for the Fund reflected the Investment Manager’s determination that the equity market was “normal.” With the “normal” form of table, the Fund’s equity investment allocations could be no less than 50% of Fund assets.
Prospectus 2024
19

Columbia Thermostat FundSM
More Information About the Fund (continued)
Stock/Bond Allocation Table
 
How the Fund will Invest
the Stock/Bond Assets
Level of the
S&P 500® Index
Stock
Percentage
Bond
Percentage
over 6701
10%
90%
between 6443 – 6701
15%
85%
between 6195 – 6443
20%
80%
between 5957 – 6195
25%
75%
between 5728 – 5957
30%
70%
between 5508 – 5728
35%
65%
between 5296 – 5508
40%
60%
between 5092 – 5296
45%
55%
between 4892 – 5092
50%
50%
between 4696 – 4892
55%
45%
between 4508 – 4696
60%
40%
between 4328 – 4508
65%
35%
between 4155 – 4328
70%
30%
between 3989 – 4155
75%
25%
between 3829 – 3989
80%
20%
between 3676 – 3829
85%
15%
under 3676
90%
10%
When the S&P 500® Index moves into a new band on the table, the Fund will rebalance the stock/bond mix to reflect the new S&P 500® Index price level by redeeming shares of some Portfolio Funds and purchasing shares of other Portfolio Funds. Any such rebalancing typically will be implemented promptly. However, there are two circumstances when a rebalancing may be implemented over a longer timeline. First, when a rebalancing or allocation table change would trigger a 10% point or greater change in stock and bond allocations or individual Portfolio Funds, the rebalancing may be implemented over a period of up to two weeks, if deemed by the Investment Manager to be in the best interest of shareholders. The second exception is a “31-day Rule;” in order to reduce taxable events and minimize short-term trading if the S&P 500® Index price moves back and forth across a band in the allocation table, after the Fund has increased its percentage allocation to either stock funds or bond funds, it will not decrease that allocation for at least 31 days. Following a change in the Fund’s stock/bond mix, if the S&P 500® Index remains within the same band for a while, normal market fluctuations will change the values of the Fund’s holdings of stock Portfolio Funds and bond Portfolio Funds. The Investment Manager will invest cash flows from sales (or redemptions) of Fund shares to bring the stock/bond mix back toward the allocation percentages for that S&P 500® Index band. For example, if the S&P 500® Index is in the 4155 band, and the value of the holdings of the stock Portfolio Funds has dropped to 68% of the value of the holdings of all Portfolio Funds, the Investment Manager would invest new cash in the stock Portfolio Funds (or cash for redemptions would come from the bond Portfolio Funds) to restore the 70% stock allocation. If the 31-day Rule is in effect, the Investment Manager will invest new cash at the stock/bond percentage allocation as of the latest rebalancing.
As another illustrative example, suppose the following:
Date
Level of the
S&P 500® Index
How the Fund will
invest the Stock/
Bond Assets(1)
Nov. 1
We begin when the market is 5000
50% stocks, 50% bonds
Dec. 1
The S&P 500® goes to 5100
rebalance 45% stocks, 55% bonds
20
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Date
Level of the
S&P 500® Index
How the Fund will
invest the Stock/
Bond Assets(1)
Dec. 6
The S&P 500® drops back to 5075
no reversal for 31 days
Jan. 2
The S&P 500® is at 5050
rebalance 50% stocks, 50% bonds
Jan. 20
The S&P 500 drops to 4800
rebalance 55% stocks, 45% bonds(2)
Jan. 30
The S&P 500® goes to 5025
no reversal for 31 days
Feb. 20
The S&P 500® is at 5075
rebalance 50% stocks, 50% bonds
(1) For each rebalancing the Fund will trade the underlying stock and bond Portfolio Funds on the next business day.
(2) The market has made a continuation move by going through a second action level, not a reversal move, so the 31-day Rule does not apply in this case.
The Investment Manager chooses the Portfolio Funds to be generally consistent with the composition of the Fund’s primary stock and bond benchmarks and to allow the Fund to participate in strategies the Investment Manager believes can provide additional return due to active management.
The stock and bond Portfolio Funds that the Fund currently uses in its “fund-of-funds” structure, and the current target percentage for each Portfolio Fund within the stock or bond asset class, is set forth below. As described more fully below, the Investment Manager may substitute or add additional Portfolio Funds at any time, including funds introduced after the date of this prospectus. The target percentage within each asset class category is achieved by rebalancing the investments within the asset class whenever the S&P 500® Index moves into a new band on the allocation table, subject to the 31-day Rule described above. The Fund will not liquidate its investment in one Portfolio Fund in order to invest in another Portfolio Fund except in connection with a rebalancing due to a move of the S&P 500® Index into a new band (or due to a change by the Investment Manager in the Portfolio Funds or to the relative target percentages among them). Until a subsequent rebalancing, the Fund’s cash flows are invested in, or redeemed from, the Portfolio Funds in a manner that will reduce any deviation of the relative values of the Fund’s holdings of the Portfolio Funds from the percentages shown below.
Allocation of Stock/Bond Assets Within Asset Classes
Stock Funds
Type of Fund
Allocation
Columbia Contrarian Core Fund
Large-cap blend
25%
Columbia Large Cap Enhanced Core Fund
Large-cap blend
25%
Columbia Large Cap Index Fund
Large-cap blend
20%
Columbia Large Cap Growth Fund
Large-cap growth
10%
Columbia Research Enhanced Core ETF
Large-cap blend
10%
Columbia Small Cap Index Fund
Small-cap blend
10%
Total
 
100%
Bond Funds
Type of Fund
Allocation
Columbia Corporate Income Fund
Corporate bond
20%
Columbia Diversified Fixed Income Allocation ETF
Multi-sector bond
10%
Columbia Quality Income Fund
Intermediate core-plus bond
15%
Columbia Total Return Bond Fund
Intermediate core-plus bond
25%
Columbia High Yield Bond Fund
High-yield bond
10%
Columbia U.S. Treasury Index Fund
Intermediate government bond
20%
Total
 
100%
See the Portfolio Funds Summary section of this prospectus for information about the Portfolio Funds’ investment objectives and principal investment strategies. Each of the Portfolio Funds is managed by the Investment Manager or its affiliates. The Fund does not pay any sales load on its purchases of shares of the Portfolio Funds.
Prospectus 2024
21

Columbia Thermostat FundSM
More Information About the Fund (continued)
The Investment Manager has the authority to review the Portfolio Funds and to change the relative percentages among them or to add or eliminate funds. Such review will occur on at least an annual basis and will be reflected in the Portfolio Funds table disclosed in this prospectus.
Determination of Current Market State
Just as a thermostat may be set at different ranges for different seasons, the Fund’s allocation of assets between stock and bond funds is expected to be set at different range bands depending principally on the Investment Manager’s view of how expensive the equity market is compared to historical levels.
At least annually, the Investment Manager will conduct a review of the current equity market price levels compared to historical price levels, and will determine if the equity market is in an “expensive” state, or a “normal” state. This review will begin with a comparison of the S&P 500® Index’s cyclically adjusted price-to-earnings ratio for the prior seven years against a 40-year history, but the Investment Manager will also take into account additional quantitative or qualitative market factors, including for example, trends in equity price measures and comparisons of equity prices against prices for other asset classes. Based on its determination of the current market state, the Investment Manager will select the form of allocation table to be effective in the Fund’s current prospectus. Also as part of this review, the Investment Manager will update the median historical information used in the table, and the resulting S&P 500® Index levels used to create the bands around the median, regardless of the market state.
As noted below, the form of table used for an “expensive” market is expected to be different from that used for a “normal” market.
Generally, the Investment Manager will determine the current state of the equity market to be “expensive” when its analysis of the S&P 500® Index’s cyclically adjusted price-to-earnings ratio for the prior seven years is within the top quartile of ratio observations over a 40-year history. The “expensive” equity market form of allocation table for the Fund is structured around an implied S&P 500® Index trading range median of 50% stocks/50% bonds (the 50/50 Band), with allocations to bonds decreasing through stratified range bands below the 50/50 Band and allocations to bonds increasing through stratified range bands above the 50/50 Band, as shown by the following example:
“Expensive” Equity Market Form of Stock/Bond Allocation Table
Level of the S&P 500® Index
Stock
Percentage
Bond
Percentage
above top of trading range
10%
90%
4% trading range above prior band's maximum price
15%
85%
4% trading range above prior band's maximum price
20%
80%
4% trading range above prior band's maximum price
25%
75%
4% trading range above prior band's maximum price
30%
70%
4% trading range above prior band's maximum price
35%
65%
4% trading range above prior band's maximum price
40%
60%
4% trading range above prior band's maximum price
45%
55%
4% trading range centered on implied median (50/50 Band)*
50%
50%
4% trading range below prior band’s minimum price
55%
45%
4% trading range below prior band’s minimum price
60%
40%
4% trading range below prior band’s minimum price
65%
35%
4% trading range below prior band’s minimum price
70%
30%
4% trading range below prior band’s minimum price
75%
25%
4% trading range below prior band’s minimum price
80%
20%
4% trading range below prior band’s minimum price
85%
15%
below bottom of trading range
90%
10%
*Implied median price level as calculated by the Investment Manager.
22
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
The “expensive” form of table was in place from the Fund’s inception in 2002 through April 30, 2020 and is currently in place since May 1, 2021.
Generally, the Investment Manager will determine the current state of the equity market to be “normal” when its analysis of the S&P 500® Index’s cyclically adjusted price-to-earnings ratio for the prior seven years is outside the top quartile of ratio observations over a 40-year history. The “normal” equity market form of allocation table for the Fund is also structured around the 50/50 Band, with allocations to bonds decreasing through stratified range bands below the 50/50 Band, and allocations to stocks and bonds set at 50% stocks/50% bonds for all trading levels above the 50/50 Band, as shown by the following example:
“Normal” Equity Market Form of Stock/Bond Allocation Table
Level of the S&P 500® Index
Stock
Percentage
Bond
Percentage
above trading range that is 2% below implied median (50/50 Band)*
50%
50%
4% trading range below prior band’s minimum price
55%
45%
4% trading range below prior band’s minimum price
60%
40%
4% trading range below prior band’s minimum price
65%
35%
4% trading range below prior band’s minimum price
70%
30%
4% trading range below prior band’s minimum price
75%
25%
4% trading range below prior band’s minimum price
80%
20%
4% trading range below prior band’s minimum price
85%
15%
below bottom of trading range
90%
10%
*Implied median price level as calculated by the Investment Manager.
The “normal” form of allocation table was in place from May 1, 2020 through April 30, 2021.
The Investment Manager will conduct the market state review at least annually prior to the annual updating of this prospectus, and may, in its discretion, assess the market state on an “emergency” basis and make any changes deemed necessary to reflect, for example, a very significant move in market levels or a structural change affecting the markets.
Any such “emergency” changes by the Investment Manager, which are expected to be infrequent, would be disclosed in this prospectus.
Principal Risks
An investment in the Fund involves risks, including general risks, as described below, relating to the Fund’s investment process and its “fund-of-funds” structure. An investment in the Fund also involves specific risks related to the individual Portfolio Funds, including but not limited to those in which it invests. These risks are listed below, which in the aggregate are considered principal risks of investing in the Fund. More information about the Portfolio Funds, including their principal risks, is available in their prospectuses. This prospectus is not an offer for any of the Portfolio Funds. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and share price may go down. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Allocation Risk. The Investment Manager uses an asset allocation strategy in pursuit of its investment objective, there is a risk that the Fund's allocation among asset classes or investments will cause the Fund's shares to lose value or cause the Fund to underperform other funds with similar investment objectives and/or strategies, or that the investments themselves will not produce the returns expected.
Fund-of-Funds Risk. Determinations regarding asset classes or Portfolio Funds and the Fund’s allocations thereto may not successfully achieve the Fund’s investment objective, in whole or in part. The selected Portfolio Funds’ performance may be lower than the performance of the asset class they were selected to represent or may be lower than the performance of alternative Portfolio Funds that could have been selected to represent the asset class. The
Prospectus 2024
23

Columbia Thermostat FundSM
More Information About the Fund (continued)
Fund also is exposed to the same risks as the Portfolio Funds in direct proportion to the allocation of its assets among the Portfolio Funds. By investing in a combination of Portfolio Funds, the Fund has exposure to the risks of many areas of the market. The ability of the Fund to realize its investment objective will depend, in large part, on the extent to which the Portfolio Funds realize their investment objectives. There is no guarantee that the Portfolio Funds will achieve their respective investment objectives. The performance of Portfolio Funds could be adversely affected if other entities that invest in the same Portfolio Funds make relatively large investments or redemptions in such Portfolio Funds. The Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each Portfolio Fund are shared by its investors, redemptions by other investors in a Portfolio Fund could result in decreased economies of scale and increased operating expenses for such fund. These transactions might also result in higher brokerage, tax or other costs for a Portfolio Fund. This risk may be particularly important when one investor owns a substantial portion of a Portfolio Fund. The Investment Manager may have potential conflicts of interest in selecting affiliated funds over unaffiliated funds for investment by the Fund, and may also face potential conflicts of interest in selecting affiliated funds, because the fees the Investment Manager receives from some Portfolio Funds may be higher than the fees paid by other Portfolio Funds. Columbia Thermostat Fund currently invests only in affiliated Portfolio Funds.
Market Risk. The Fund may incur losses due to declines in the value of one or more securities in which it invests. These declines may be due to factors affecting a particular issuer, or the result of, among other things, political, regulatory, market, economic or social developments affecting the relevant market(s) more generally. In addition, turbulence in financial markets and reduced liquidity in equity, credit and/or fixed income markets may negatively affect many issuers, which could adversely affect the Fund’s ability to price or value hard-to-value assets in thinly traded and closed markets and could cause significant redemptions and operational challenges. Global economies and financial markets are increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market. These risks may be magnified if certain events or developments adversely interrupt the global supply chain; in these and other circumstances, such risks might affect companies worldwide. As a result, local, regional or global events such as terrorism, war, other conflicts, natural disasters, disease/virus outbreaks and epidemics or other public health issues, recessions, depressions or other events – or the potential for such events – could have a significant negative impact on global economic and market conditions.
The large-scale invasion of Ukraine by Russia in February 2022 has resulted in sanctions and market disruptions, including declines in regional and global stock markets, unusual volatility in global commodity markets and significant devaluations of Russian currency. The extent and duration of the military action are impossible to predict but could continue to be significant. Market disruption caused by the Russian military action, and any countermeasures or responses thereto (including international sanctions, a downgrade in a country’s credit rating, purchasing and financing restrictions, boycotts, tariffs, changes in consumer or purchaser preferences, cyberattacks and espionage) could continue to have severe adverse impacts on regional and/or global securities and commodities markets, including markets for oil and natural gas. These impacts may include reduced market liquidity, distress in credit markets, further disruption of global supply chains, increased risk of inflation, and limited access to investments in certain international markets and/or issuers. These developments and other related events could negatively impact Fund performance.
Frequent Trading Risk. The portfolio managers may actively and frequently trade investments in the Fund's portfolio to carry out its investment strategies. Frequent trading of investments increases the possibility that the Fund, as relevant, will realize taxable capital gains (including short-term capital gains, which are generally taxable to shareholders at higher rates than long-term capital gains for U.S. federal income tax purposes), which could reduce the Fund’s after-tax return. Frequent trading can also mean higher brokerage and other transaction costs, which could reduce the Fund's return. The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund’s performance.
24
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
The Fund is subject indirectly to the risks of the Portfolio Funds in which it invests. These risks are listed below. References to the “Fund” in the risk disclosures below refer to the Portfolio Funds and not Columbia Thermostat Fund. References to the “Investment Manager” in the risk disclosures below refer to the Fund's Investment Manager and/or Columbia Management as appropriate. Please see the Portfolio Funds Summary in this prospectus for information about the risks that apply to the Portfolio Funds.
Active Management Risk. The Fund is actively managed and its performance therefore will reflect, in part, the ability of the portfolio managers to make investment decisions that seek to achieve the Fund’s investment objective. Due to its active management, the Fund could underperform its benchmark index and/or other funds with similar investment objectives and/or strategies.
Interest Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if interest rates rise, the values of loans and other debt instruments tend to fall, and if interest rates fall, the values of loans and other debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. Interest rate declines also may increase prepayments of debt obligations, which, in turn, would increase prepayment risk (the risk that the Fund will have to reinvest the money received in securities that have lower yields). The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates. Higher periods of inflation could lead such authorities to raise interest rates. Such actions may negatively affect the value of debt instruments held by the Fund, resulting in a negative impact on the Fund's performance and NAV. Debt instruments with floating coupon rates are typically less sensitive to interest rate changes, but these debt instruments may decline in value if their coupon rates do not rise as much as, or keep pace with, yields on such types of debt instruments. Because rates on certain floating rate loans and other debt instruments reset only periodically, changes in interest rates (and particularly sudden and significant changes) can be expected to cause fluctuations in the Fund’s NAV. Any interest rate increases could cause the value of the Fund’s investments in debt instruments to decrease. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses.
Credit Risk. Credit risk is the risk that the value of loans or other debt instruments may decline if the issuer thereof defaults or otherwise becomes unable or unwilling, or is perceived to be unable or unwilling, to honor its financial obligations, such as making payments to the Fund when due. Various factors could affect the actual or perceived willingness or ability of the issuer to make timely interest or principal payments, including changes in the financial condition of the issuer or in general economic conditions.  Credit rating agencies, such as S&P Global Ratings, Moody’s Investors Service, Inc. (Moody’s), Fitch Ratings, Inc. (Fitch), Morningstar DBRS (DBRS) and Kroll Bond Rating Agency, LLC (KBRA), assign credit ratings to certain debt instruments to indicate their credit risk. A rating downgrade by such agencies can negatively impact the value of such instruments. Lower-rated or unrated instruments held by the Fund may present increased credit risk as compared to higher-rated instruments. Non-investment grade debt instruments may be subject to greater price fluctuations and are more likely to experience a default than investment grade debt instruments and therefore may expose the Fund to increased credit risk. If the Fund purchases unrated instruments, or if the ratings of instruments held by the Fund are lowered after purchase, the Fund will depend on analysis of credit risk more heavily than usual.
High-Yield Investments Risk. Securities and other debt instruments held by the Fund that are rated below investment grade (commonly called “high-yield” or “junk” bonds) and unrated debt instruments of comparable quality tend to be more sensitive to credit risk than higher-rated debt instruments and may experience greater price fluctuations in response to perceived changes in the ability of the issuing entity or obligor to pay interest and principal when due than to changes in interest rates. These investments are generally more likely to experience a default than higher-rated debt instruments. High-yield debt instruments are considered to be predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal. These debt instruments typically pay a premium – a higher interest rate or yield – because of the increased risk of loss, including default. High-yield debt instruments may require a greater degree of judgment to establish a price, may be difficult to sell at the time and price the Fund
Prospectus 2024
25

Columbia Thermostat FundSM
More Information About the Fund (continued)
desires, may carry high transaction costs, and also are generally less liquid than higher-rated debt instruments. The ratings provided by third party rating agencies are based on analyses by these ratings agencies of the credit quality of the debt instruments and may not take into account every risk related to whether interest or principal will be timely repaid. In adverse economic and other circumstances, issuers of lower-rated debt instruments are more likely to have difficulty making principal and interest payments than issuers of higher-rated debt instruments.
Value Securities Risk. Value securities are securities of companies that may have experienced, for example, adverse business, industry or other developments or may be subject to special risks that have caused the securities to be out of favor and, in turn, potentially undervalued. The market value of a portfolio security may not meet the Portfolio Fund’s Investment Manager’s perceived value assessment of that security, or may decline in price, even though the Portfolio Fund’s Investment Manager believes the securities are already undervalued. There is also a risk that it may take longer than expected for the value of these investments to rise to the portfolio managers’ perceived value. In addition, value securities, at times, may not perform as well as growth securities or the stock market in general, and may be out of favor with investors for varying periods of time.
Growth Securities Risk. Growth securities typically trade at a higher multiple of earnings than other types of equity securities. Accordingly, the market values of growth securities may never reach their expected market value and may decline in price. In addition, growth securities, at times, may not perform as well as value securities or the stock market in general, and may be out of favor with investors for varying periods of time. Growth securities may also be sensitive to movements in interest rates.
Sector Risk. At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in an industry or related group of industries within one or more economic sectors. Companies in the same sector may be similarly affected by economic, regulatory, political or market events or conditions, which may make the Fund vulnerable to unfavorable developments in that industry, group of industries or economic sector.
Financial Services Sector. The Fund is vulnerable to the particular risks that may affect companies in the financial services sector. Companies in the financial services sector are subject to certain risks, including the risk of regulatory change, decreased liquidity in credit markets and unstable interest rates. Such companies may have concentrated portfolios, such as a high level of loans to one or more industries or sectors, which makes them vulnerable to economic conditions that affect such industries or sectors. Performance of such companies may be affected by competitive pressures and exposure to investments, agreements and counterparties, including credit products that, under certain circumstances, may lead to losses (e.g., subprime loans). Companies in the financial services sector are subject to extensive governmental regulation that may limit the amount and types of loans and other financial commitments they can make, and the interest rates and fees they may charge. In addition, profitability of such companies is largely dependent upon the availability and the cost of capital.
Information Technology Sector. The Fund is vulnerable to the particular risks that may affect companies in the information technology sector. Companies in the information technology sector are subject to certain risks, including the risk that new services, equipment or technologies will not be accepted by consumers and businesses or will become rapidly obsolete. Performance of such companies may be affected by factors including obtaining and protecting patents (or the failure to do so) and significant competitive pressures, including aggressive pricing of their products or services, new market entrants, competition for market share and short product cycles due to an accelerated rate of technological developments. Such competitive pressures may lead to limited earnings and/or falling profit margins. As a result, the value of their securities may fall or fail to rise. In addition, many information technology sector companies have limited operating histories and prices of these companies’ securities historically have been more volatile than other securities, especially over the short term. Some companies in the information technology sector are facing increased government and regulatory scrutiny and may be subject to adverse government or regulatory action, which could negatively impact the value of their securities.
Foreign Securities Risk. Investments in or exposure to securities of foreign companies may involve heightened risks relative to investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. Foreign securities may also be less liquid, making them more difficult to trade, than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs and other fees are also generally higher for foreign securities. The Fund may
26
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. In addition, foreign governments may impose withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. In some cases, such withholding or other taxes could potentially be confiscatory. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events (including, for example, military confrontations and actions, war, other conflicts, terrorism and disease/virus outbreaks and epidemics), possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices, which could result in losses to the Fund and increased transaction costs. These conditions may be in place for a substantial period of time and enacted with limited advance notice to the Fund. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets. Additionally, investments in certain countries may subject the Fund to a number of tax rules, the application of which may be uncertain. Countries may amend or revise their existing tax laws, regulations and/or procedures in the future, possibly with retroactive effect. Changes in or uncertainties regarding the laws, regulations or procedures of a country could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies located in such countries in which the Fund invests, or result in unexpected tax liabilities for the Fund.
Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (foreign sub-custodians), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.
Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Portfolio Fund’s Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.
Prospectus 2024
27

Columbia Thermostat FundSM
More Information About the Fund (continued)
Loan Interests Risk. Loan interests may not be considered “securities,” and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws. Loan interests generally are subject to restrictions on transfer, and the Fund may be unable to sell its loan interests at a time when it may otherwise be desirable to do so or may be able to sell them only at prices that are less than what the Fund regards as their fair market value. Accordingly, loan interests may at times be illiquid. Loan interests may be difficult to value and typically have extended settlement periods (generally greater than 7 days). Extended settlement periods during significant Fund redemption activity could potentially cause increased short-term liquidity demands on the Fund. As a result, the Fund may be forced to sell investments at unfavorable prices, or borrow money or effect short settlements where possible (at a cost to the Fund), in an effort to generate sufficient cash to pay redeeming shareholders. The Fund’s actions in this regard may not be successful. Interests in loans created to finance highly leveraged companies or transactions, such as corporate acquisitions, may be especially vulnerable to adverse changes in economic or market conditions. Interests in secured loans have the benefit of collateral and, typically, of restrictive covenants limiting the ability of the borrower to further encumber its assets. There is a risk that the value of any collateral securing a loan in which the Fund has an interest may decline and that the collateral may not be sufficient to cover the amount owed on the loan. In the event the borrower defaults, the Fund’s access to the collateral may be limited or delayed by bankruptcy or other insolvency laws. Further, there is a risk that a court could take action with respect to a loan that is adverse to the holders of the loan, and the Fund, to enforce its rights in the event of a default, bankruptcy or similar situation, may need to retain legal or similar counsel. This may increase the Fund’s operating expenses and adversely affect its NAV. Loans that have a lower priority for repayment in an issuer’s capital structure may involve a higher degree of overall risk than more senior loans of the same borrower. In the event of a default, second lien secured loans will generally be paid only if the value of the collateral exceeds the amount of the borrower’s obligations to the first lien secured lenders, and the remaining collateral may not be sufficient to cover the full amount owed on the loan in which the Fund has an interest. The Fund may acquire a participation interest in a loan that is held by another party. When the Fund’s loan interest is a participation, the Fund may have less control over the exercise of remedies than the party selling the participation interest, and it normally would not have any direct rights against the borrower.
Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) than more developed countries. Emerging market securities tend to be more volatile, and may be more susceptible to market manipulation, than securities in more developed markets. Many emerging market countries are heavily dependent on international trade and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries. Due to the differences in the nature and quality of financial information of issuers of emerging market securities, including auditing and financial reporting standards, financial information and disclosures about such issuers may be unavailable or, if made available, may be considerably less reliable than publicly available information about other foreign securities.
Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades.
28
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not have an active trading market internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.
Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in China and Russia.
Sovereign Debt Risk. The willingness or ability of a sovereign or quasi-sovereign debtor to repay principal and pay interest in a timely manner may be affected by a variety of factors, including its cash flow situation, the extent of its reserves, the availability of sufficient foreign exchange on the date a payment is due, the relative size of the debt service burden to the economy as a whole, the sovereign or quasi-sovereign debtor’s policy toward international lenders, and the political constraints to which such debtor may be subject.
With respect to sovereign or quasi-sovereign debt of emerging market issuers, investors should be aware that certain emerging market countries are among the largest debtors to commercial banks and foreign governments. At times, certain emerging market countries have declared moratoria on the payment of principal and interest on external debt. Certain emerging market countries have experienced difficulty in servicing their sovereign or quasi-sovereign debt on a timely basis and that has led to defaults and the restructuring of certain indebtedness to the detriment of debt holders.
Foreign Currency Risk. The performance of the Fund may be materially affected positively or negatively by foreign currency strength or weakness relative to the U.S. dollar, particularly if the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar. Currency rates in foreign countries may fluctuate significantly over short or long periods of time for a number of reasons, including changes in interest rates, imposition of currency controls and economic or political developments in the U.S. or abroad. The Fund may also incur currency conversion costs when converting foreign currencies into U.S. dollars and vice versa. Restrictions on currency trading may be imposed by foreign countries, which may adversely affect the value of your investment in the Fund. Even though the currencies of some countries may be pegged to the U.S. dollar, the conversion rate may be controlled by government regulation or intervention at levels significantly different than what would normally prevail in a free market. Significant revaluations of the U.S. dollar exchange rate of these currencies could cause substantial reductions in the Fund’s NAV.
Issuer Risk. An issuer in which the Fund invests or to which it has exposure may perform poorly or below expectations, and the value of its securities may therefore decline, which may negatively affect the Fund’s performance. Underperformance of an issuer may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters, military confrontations and actions, war, other conflicts, terrorism, disease/virus outbreaks, epidemics or other events, conditions and factors which may impair the value of your investment in the Fund.
Small- and Mid-Cap Stock Risk. Investments in small- and mid-capitalization companies (small- and mid-cap companies) often involve greater risks than investments in larger, more established companies (larger companies)
Prospectus 2024
29

Columbia Thermostat FundSM
More Information About the Fund (continued)
because small- and mid-cap companies tend to have less predictable earnings and may lack the management experience, financial resources, product diversification and competitive strengths of larger companies. Securities of small- and mid-cap companies may be less liquid and more volatile than the securities of larger companies.
Large-Cap Stock Risk. Investments in larger companies may involve certain risks associated with their larger size. For instance, larger companies may be less able to respond quickly to new competitive challenges, such as changes in consumer tastes or innovation from smaller competitors. Also, larger companies are sometimes less able to achieve as high growth rates as successful smaller companies, especially during extended periods of economic expansion.
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or may be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. For example, securities issued by the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association and the Federal Home Loan Banks are neither insured nor guaranteed by the U.S. Government. These securities may be supported by the ability to borrow from the U.S. Treasury or only by the credit of the issuing agency, authority, instrumentality or enterprise and, as a result, are subject to greater credit risk than securities issued or guaranteed by the U.S. Treasury.
Derivatives Risk. Derivatives may involve significant risks. Derivatives are financial instruments, traded on an exchange or in the over-the-counter (OTC) markets, with a value in relation to, or derived from, the value of an underlying asset(s) (such as a security, commodity or currency) or other reference, such as an index, rate or other economic indicator (each an underlying reference). Derivatives may include those that are privately placed or otherwise exempt from SEC registration, including certain Rule 144A eligible securities. Derivatives could result in Fund losses if the underlying reference does not perform as anticipated. Use of derivatives is a highly specialized activity that can involve investment techniques, risks, and tax planning different from those associated with more traditional investment instruments. The Fund’s derivatives strategy may not be successful and use of certain derivatives could result in substantial, potentially unlimited, losses to the Fund regardless of the Fund’s actual investment. A relatively small movement in the price, rate or other economic indicator associated with the underlying reference may result in substantial losses for the Fund. Derivatives may be more volatile than other types of investments. Derivatives can increase the Fund’s risk exposure to underlying references and their attendant risks, including the risk of an adverse credit event associated with the underlying reference (credit risk), the risk of an adverse movement in the value, price or rate of the underlying reference (market risk), the risk of an adverse movement in the value of underlying currencies (foreign currency risk) and the risk of an adverse movement in underlying interest rates (interest rate risk). Derivatives may expose the Fund to additional risks, including the risk of loss due to a derivative position that is imperfectly correlated with the underlying reference it is intended to hedge or replicate (correlation risk), the risk that a counterparty will fail to perform as agreed (counterparty risk), the risk that a hedging strategy may fail to mitigate losses, and may offset gains (hedging risk), the risk that the return on an investment may not keep pace with inflation (inflation risk), the risk that losses may be greater than the amount invested (leverage risk), the risk that the Fund may be unable to sell an investment at an advantageous time or price (liquidity risk), the risk that the investment may be difficult to value (pricing risk), and the risk that the price or value of the investment fluctuates significantly over short periods of time (volatility risk). The value of derivatives may be influenced by a variety of factors, including national and international political and economic developments. Potential changes to the regulation of the derivatives markets may make derivatives more costly, may limit the market for derivatives, or may otherwise adversely affect the value or performance of derivatives.
Derivatives Risk – Futures Contracts Risk. A futures contract is an exchange-traded derivative transaction between two parties in which a buyer (holding the “long” position) agrees to pay a fixed price (or rate) at a specified future date for delivery of an underlying reference from a seller (holding the “short” position). The seller hopes that the market price on the delivery date is less than the agreed upon price, while the buyer hopes for the contrary. Certain futures contract markets are highly volatile, and futures contracts may be illiquid. Futures exchanges may limit fluctuations in futures contract prices by imposing a maximum permissible daily price movement. The Fund may be
30
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. At or prior to maturity of a futures contract, the Fund may enter into an offsetting contract and may incur a loss to the extent there has been adverse movement in futures contract prices. The liquidity of the futures markets depends on participants entering into offsetting transactions rather than making or taking delivery. To the extent participants make or take delivery, liquidity in the futures market could be reduced. Positions in futures contracts may be closed out only on the exchange on which they were entered into or through a linked exchange, and no secondary market exists for such contracts. Futures positions are marked to market each day and variation margin payment must be paid to or by the Fund. Because of the low margin deposits normally required in futures trading, it is possible that the Fund may employ a high degree of leverage in the portfolio. As a result, a relatively small price movement in a futures contract may result in substantial losses to the Fund, exceeding the amount of the margin paid. For certain types of futures contracts, losses are potentially unlimited. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s NAV. Futures contracts executed (if any) on foreign exchanges may not provide the same protection as U.S. exchanges. Futures contracts can increase the Fund’s risk exposure to underlying references and their attendant risks, such as credit risk, market risk, foreign currency risk, and interest rate risk, while also exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.
An interest rate future is a derivative that is an agreement whereby the buyer and seller agree to the future delivery of an interest-bearing instrument on a specific date at a pre-determined price. Examples include Treasury-bill futures, Treasury-bond futures and Eurodollar futures.
Derivatives Risk – Options Risk. Options are derivatives that give the purchaser the option to buy (call) or sell (put) an underlying reference from or to a counterparty at a specified price (the strike price) on or before an expiration date. When writing options, the Fund is exposed to the risk that it may be required to buy or sell the underlying reference at a disadvantageous price on or before the expiration date. Options may involve economic leverage, which could result in greater volatility in price movement. The Fund's losses could be significant, and are potentially unlimited for certain types of options. Options may be traded on a securities exchange or in the over-the-counter market. At or prior to maturity of an options contract, the Fund may enter into an offsetting contract and may incur a loss to the extent there has been adverse movement in options prices. Options can increase the Fund’s risk exposure to underlying references and their attendant risks such as credit risk, market risk, foreign currency risk and interest rate risk, while also exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.
Derivatives Risk – Swaps Risk. In a typical swap transaction, two parties agree to exchange the return earned on a specified underlying reference for a fixed return or the return from another underlying reference during a specified period of time. Swaps may be difficult to value and may be illiquid. Swaps could result in Fund losses if the underlying asset or reference does not perform as anticipated. Swaps create significant investment leverage such that a relatively small price movement in a swap may result in immediate and substantial losses to the Fund. The Fund may only close out a swap with its particular counterparty, and may only transfer a position with the consent of that counterparty. Certain swaps, such as short swap transactions and total return swaps, have the potential for unlimited losses, regardless of the size of the initial position. Swaps can increase the Fund’s risk exposure to underlying references and their attendant risks, such as credit risk, market risk, foreign currency risk,  and interest rate risk, while also exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.
A credit default swap (including a swap on a credit default index, sometimes referred to as a credit default swap index) is a derivative and special type of swap where one party pays, in effect, an insurance premium through a stream of payments to another party in exchange for the right to receive a specified return upon the occurrence of a particular credit event by one or more third parties, such as bankruptcy, default or a similar event. A credit default swap may be embedded within a structured note or other derivative instrument. Credit default swaps enable an investor to buy or sell protection against such a credit event (such as an issuer’s bankruptcy, restructuring or failure to make timely payments of interest or principal). Credit default swap indices are indices that reflect the performance of a basket of credit default swaps and are subject to the same risks as credit default swaps. If such a default were to occur, any contractual remedies that the Fund may have may be subject to
Prospectus 2024
31

Columbia Thermostat FundSM
More Information About the Fund (continued)
bankruptcy and insolvency laws, which could delay or limit the Fund's recovery. Thus, if the counterparty under a credit default swap defaults on its obligation to make payments thereunder, as a result of its bankruptcy or otherwise, the Fund may lose such payments altogether, or collect only a portion thereof, which collection could involve costs or delays. The Fund’s return from investment in a credit default swap index may not match the return of the referenced index. Further, investment in a credit default swap index could result in losses if the referenced index does not perform as expected. Unexpected changes in the composition of the index may also affect performance of the credit default swap index. If a referenced index has a dramatic intraday move that causes a material decline in the Fund’s net assets, the terms of the Fund’s credit default swap index may permit the counterparty to immediately close out the transaction. In that event, the Fund may be unable to enter into another credit default swap index or otherwise achieve desired exposure, even if the referenced index reverses all or a portion of its intraday move.
Derivatives Risk – Swaptions Risk. A swaption is an options contract on a swap agreement. These transactions give the purchasing party the right (but not the obligation) to enter into new swap agreements or to shorten, extend, cancel or otherwise modify an existing swap agreement at some designated future time on specified terms, in return for payment of the purchase price (the “premium”) of the option. The Fund may write (sell) and purchase put and call swaptions to the same extent it may make use of standard options on securities or other instruments. The writer of the contract receives the premium and bears the risk of unfavorable changes in the market value on the underlying swap agreement. Swaptions can be bundled and sold as a package. These are commonly called interest rate caps, floors and collars.
Impairment of Collateral Risk. The value of collateral, if any, securing a loan can decline, and may be insufficient to meet the borrower’s obligations or difficult or costly to liquidate. In addition, the Fund’s access to collateral may be limited by bankruptcy or other insolvency laws. Further, certain floating rate and other loans may not be fully collateralized and may decline in value.
Convertible Securities Risk. Convertible securities are subject to the usual risks associated with debt instruments, such as interest rate risk (the risk of losses attributable to changes in interest rates) and credit risk (the risk that the issuer of a debt instrument will default or otherwise become unable, or be perceived to be unable or unwilling, to honor a financial obligation, such as making payments to the Fund when due). Convertible securities also react to changes in the value of the common stock into which they convert, and are thus subject to market risk (the risk that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise). Because the value of a convertible security can be influenced by both interest rates and the common stock's market movements, a convertible security generally is not as sensitive to interest rates as a similar debt instrument, and generally will not vary in value in response to other factors to the same extent as the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would typically be paid before the company's common stockholders but after holders of any senior debt obligations of the company. The Fund may be forced to convert a convertible security before it otherwise would choose to do so, which may decrease the Fund's return.
Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk. When purchasing mortgage-backed securities in the “to be announced” (TBA) market (MBS TBAs), the seller agrees to deliver mortgage-backed securities for an agreed upon price on an agreed upon date, but may make no guarantee as to the specific securities to be delivered. In lieu of taking delivery of mortgage-backed securities, the Fund could enter into dollar rolls, which are transactions in which the Fund sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities the Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase the Fund’s portfolio turnover rate. If the Fund reinvests the proceeds of the security sold, the Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk). MBS TBAs and dollar rolls are subject to the risk that the counterparty to the transaction may not perform or be unable to perform in accordance with the terms of the instrument.
32
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Prepayment and Extension Risk. Prepayment and extension risk is the risk that a bond or other security or investment might, in the case of prepayment risk, be called or otherwise converted, prepaid or redeemed before maturity and, in the case of extension risk, that the investment might not be called as expected. In the case of prepayment risk, if the investment is converted, prepaid or redeemed before maturity, the portfolio managers may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to the Fund. As interest rates decrease or spreads narrow on such securities, the likelihood of prepayment increases. Conversely, extension risk is the risk that an unexpected rise in interest rates will extend the life of a security beyond the prepayment time. If the Fund's investments are locked in at a lower interest rate for a longer period of time, the portfolio managers may be unable to capitalize on securities with higher interest rates or wider spreads.
Reinvestment Risk. Reinvestment risk arises when the Fund is unable to reinvest income or principal at the same or at least the same return it is currently earning.
Depositary Receipts Risk. Depositary receipts are receipts issued by a bank or trust company reflecting ownership of underlying securities issued by foreign companies. Some foreign securities are traded in the form of American Depositary Receipts and/or Global Depositary Receipts. Depositary receipts involve risks similar to the risks associated with investments in foreign securities, including those associated with an issuer’s (and any of its related companies’) country of organization and places of business operations, which may be related to the particular political, regulatory, economic, social and other conditions or events (including, for example, military confrontations and actions, war, other conflicts, terrorism and disease/virus outbreaks and epidemics) occurring in the country and fluctuations in such country’s currency, as well as market risk tied to the underlying foreign company. In addition, holders of depositary receipts may have limited voting rights, may not have the same rights afforded to stockholders of a typical domestic company in the event of a corporate action, such as an acquisition, merger or rights offering, and may experience difficulty in receiving company stockholder communications. There is no guarantee that a financial institution will continue to sponsor a depositary receipt, or that a depositary receipt will continue to trade on an exchange, either of which could adversely affect the liquidity, availability and pricing of the depositary receipt. Changes in foreign currency exchange rates will affect the value of depositary receipts and, therefore, may affect the value of your investment in the Fund.
Changing Distribution Level Risk. The Fund normally expects to receive income which may include interest, dividends and/or capital gains, depending upon its investments. The distribution amounts paid by the Fund will vary and generally depend on the amount of income the Fund earns (less expenses) on its portfolio holdings, and capital gains or losses it recognizes. A decline in the Fund’s income or net capital gains arising from its investments may reduce its distribution level.
Highly Leveraged Transactions Risk. The loans or other debt instruments in which the Fund invests may include highly leveraged transactions whereby the borrower assumes large amounts of debt in order to have the financial resources to attempt to achieve its business objectives. Loans or other debt instruments that are part of highly leveraged transactions involve a greater risk (including default and bankruptcy) than other investments.
Quantitative Models Risk. Quantitative models used by the Fund may not effectively identify purchases and sales of Fund investments and may cause the Fund to underperform other investment strategies. Flaws or errors in the quantitative model’s assumptions, design, execution, or data inputs may adversely affect Fund performance. Quantitative models may not perform as expected and may underperform in certain market environments including in stressed or volatile market conditions. There can be no assurance that the use of quantitative models will enable the Fund to achieve its objective.
Rule 144A and Other Exempted Securities Risk. The Fund may invest in privately placed and other securities or instruments exempt from SEC registration (collectively “private placements”), subject to certain regulatory restrictions. In the U.S. market, private placements are typically sold only to qualified institutional buyers, or qualified purchasers, as applicable. An insufficient number of buyers interested in purchasing private placements at a particular time could adversely affect the marketability of such investments and the Fund might be unable to dispose of them promptly or at reasonable prices, subjecting the Fund to liquidity risk (the risk that it may not be possible for the Fund to liquidate the instrument at an advantageous time or price). The Fund’s holdings of private placements
Prospectus 2024
33

Columbia Thermostat FundSM
More Information About the Fund (continued)
may increase the level of Fund illiquidity if eligible buyers are unable or unwilling to purchase them at a particular time. The Fund may also have to bear the expense of registering the securities for resale and the risk of substantial delays in effecting the registration. Additionally, the purchase price and subsequent valuation of private placements typically reflect a discount, which may be significant, from the market price of comparable securities for which a more liquid market exists. Issuers of Rule 144A eligible securities are required to furnish information to potential investors upon request. However, the required disclosure is much less extensive than that required of public companies and is not publicly available since the offering information is not filed with the SEC. Further, issuers of Rule 144A eligible securities can require recipients of the offering information (such as the Fund) to agree contractually to keep the information confidential, which could also adversely affect the Fund’s ability to dispose of the security.
Counterparty Risk. Counterparty risk is the risk that a counterparty to a transaction in a financial instrument held by the Fund or by a special purpose or structured vehicle invested in by the Fund may become insolvent or otherwise fail to perform its obligations. As a result, the Fund may obtain no or limited recovery of its investment, and any recovery may be significantly delayed.
Confidential Information Access Risk. The portfolio managers may avoid the receipt of material, non-public information (Confidential Information) about the issuers of floating rate loans (including from the issuer itself) being considered for acquisition by the Fund, or held in the Fund. A decision not to receive Confidential Information may disadvantage the Fund and could adversely affect the Fund’s performance.
Liquidity Risk. Liquidity risk is the risk associated with any event, circumstance, or characteristic of an investment or market that negatively impacts the Fund’s ability to sell, or realize the proceeds from the sale of, an investment at a desirable time or price. Liquidity risk may arise because of, for example, a lack of marketability of the investment, which means that when seeking to sell its portfolio investments, the Fund could find that selling is more difficult than anticipated, especially during times of high market volatility. Decreases in the number of financial institutions, including banks and broker-dealers, willing to make markets (match up sellers and buyers) in the Fund’s investments or decreases in their capacity or willingness to trade such investments may increase the Fund’s exposure to this risk. The debt market has experienced considerable growth, and financial institutions making markets in instruments purchased and sold by the Fund (e.g., bond dealers) have been subject to increased regulation. The impact of that growth and regulation on the ability and willingness of financial institutions to engage in trading or “making a market” in such instruments remains unsettled. Certain types of investments, such as lower-rated securities or those that are purchased and sold in over-the-counter markets, may be especially subject to liquidity risk. Securities or other assets in which the Fund invests may be traded in the over-the-counter market rather than on an exchange and therefore may be more difficult to purchase or sell at a fair price, which may have a negative impact on the Fund’s performance. Market participants attempting to sell the same or a similar instrument at the same time as the Fund could exacerbate the Fund’s exposure to liquidity risk. The Fund may have to accept a lower selling price for the holding, sell other liquid or more liquid investments that it might otherwise prefer to hold (thereby increasing the proportion of the Fund’s investments in less liquid or illiquid securities), or forego another more appealing investment opportunity. The liquidity of Fund investments may change significantly over time and certain investments that were liquid when purchased by the Fund may later become illiquid, particularly in times of overall economic distress. Changing regulatory, market or other conditions or environments (for example, the interest rate or credit environments) may also adversely affect the liquidity and the price of the Fund's investments. Judgment plays a larger role in valuing illiquid or less liquid investments as compared to valuing liquid or more liquid investments. Price volatility may be higher for illiquid or less liquid investments as a result of, for example, the relatively less frequent pricing of such securities (as compared to liquid or more liquid investments). Generally, the less liquid the market at the time the Fund sells a portfolio investment, the greater the risk of loss or decline of value to the Fund. Overall market liquidity and other factors can lead to an increase in redemptions, which may negatively impact Fund performance and NAV, including, for example, if the Fund is forced to sell investments in a down market.
Mortgage- and Other Asset-Backed Securities Risk. The value of any mortgage-backed and other asset-backed securities including collateralized debt obligations and collateralized loan obligations, if any, held by the Fund may be affected by, among other things, changes or perceived changes in: interest rates; factors concerning the interests in and structure of the issuer or the originator of the mortgages or other assets; the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements; or the market's assessment
34
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
of the quality of underlying assets. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed by the full faith and credit of a particular U.S. Government agency, authority, enterprise or instrumentality, and some, but not all, are also insured or guaranteed by the U.S. Government. Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may entail greater risk than obligations guaranteed by the U.S. Government. Mortgage- and other asset-backed securities are subject to liquidity risk and prepayment risk. A decline or flattening of housing values may cause delinquencies in mortgages (especially sub-prime or non-prime mortgages) underlying mortgage-backed securities and thereby adversely affect the ability of the mortgage-backed securities issuer to make principal and/or interest payments to mortgage-backed securities holders, including the Fund. Rising or high interest rates tend to extend the duration of mortgage- and other asset-backed securities, making their prices more volatile and more sensitive to changes in interest rates.
Frequent Trading Risk. The portfolio managers may actively and frequently trade investments in the Fund's portfolio to carry out its investment strategies. Frequent trading of investments increases the possibility that the Fund, as relevant, will realize taxable capital gains (including short-term capital gains, which are generally taxable to shareholders at higher rates than long-term capital gains for U.S. federal income tax purposes), which could reduce the Fund’s after-tax return. Frequent trading can also mean higher brokerage and other transaction costs, which could reduce the Fund's return. The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund’s performance.
Leverage Risk. Leverage occurs when the Fund increases its assets available for investment using borrowings, derivatives, or similar instruments or techniques. Use of leverage can produce volatility and may exaggerate changes in the Fund’s NAV and in the return on the Fund’s portfolio, which may increase the risk that the Fund will lose more than it has invested. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any applicable regulatory limits. Futures contracts, options on futures contracts, forward contracts and other derivatives can allow the Fund to obtain large investment exposures in return for meeting relatively small margin requirements. As a result, investments in those transactions may be highly leveraged. If the Fund uses leverage, through the purchase of particular instruments such as derivatives, the Fund may experience capital losses that exceed the net assets of the Fund. Leverage can create an interest expense that may lower the Fund's overall returns. Leverage presents the opportunity for increased net income and capital gains, but may also exaggerate the Fund's volatility and risk of loss. There can be no guarantee that a leveraging strategy will be successful.
Stripped Mortgage-Backed Securities Risk. Stripped mortgage-backed securities are a type of mortgage-backed security that receive differing proportions of the interest and principal payments from the underlying assets. Generally, there are two classes of stripped mortgage-backed securities: Interest Only (IO) and Principal Only (PO). IOs entitle the holder to receive distributions consisting of all or a portion of the interest on the underlying pool of mortgage loans or mortgage-backed securities. POs entitle the holder to receive distributions consisting of all or a portion of the principal of the underlying pool of mortgage loans or mortgage-backed securities. The cash flows and yields on IOs and POs are extremely sensitive to the rate of principal payments (including prepayments) on the underlying mortgage loans or mortgage-backed securities. A rapid rate of principal payments may adversely affect the yield to maturity of IOs. A slow rate of principal payments may adversely affect the yield to maturity of POs. If prepayments of principal are greater than anticipated, an investor in IOs may incur substantial losses. If prepayments of principal are slower than anticipated, the yield on a PO will be affected more severely than would be the case with a traditional mortgage-backed security.
Valuation Risk. The sales price the Fund could receive, or actually receives, for any particular investment may differ from the Fund’s valuation of the investment, particularly for securities that trade in thin or volatile markets, debt securities sold in amounts less than institutional-sized lots (typically referred to as odd lots) or securities that are valued using a fair value methodology that produces an estimate of the fair value of the security/instrument.
The Fund is subject indirectly to the following risks of Portfolio Funds seeking returns that correspond to a stated market index (the Index).
Prospectus 2024
35

Columbia Thermostat FundSM
More Information About the Fund (continued)
Passive Investment Risk. The Fund is not “actively” managed and may be affected by a general decline in market segments related to its underlying index. The Fund invests in securities or instruments included in, or believed by the Portfolio Fund’s Investment Manager to be representative of, its underlying index, regardless of their investment merits. The Fund does not seek temporary defensive positions when markets decline or appear overvalued.
Index Fund Risk. An index fund seeks to track the performance of the Index by using indexing strategies and, therefore, would not necessarily sell a security because the security’s issuer was in financial trouble or defaulted, or whose credit rating was downgraded, unless that security was removed from the Index. Except for Columbia Research Enhanced Core ETF, the decision of whether to remove a security from an index is made by an independent index provider who is not affiliated with the Fund or the Investment Manager or its affiliates. The index which Columbia Research Enhanced Core ETF seeks to track is owned and/or was developed by Columbia Management.
Index Methodology Risk. An index fund seeks performance that corresponds to the performance of the Index. There is no guarantee or assurance that the Index will achieve high, or even positive, returns. The Index may underperform more traditional indices. In turn, the Fund could lose value while other indices or measures of market performance increase in value or performance. In addition, the Fund may be subject to the risk that the index provider may make errors in Index computation, construction, reconstitution and/or rebalancing despite any index provider procedures designed to prevent such occurrences and despite due diligence conducted by the investment manager or the index provider. Errors may result in a negative performance impact to the Fund and its shareholders.
Correlation/Tracking Error Risk. An index fund’s value will generally decline when the performance of the securities within the Index declines. A number of factors may affect the Fund’s ability to achieve a high degree of correlation with the Index, and there is no guarantee that the Fund will achieve a high degree of correlation. Failure to achieve a high degree of correlation may prevent the Fund from achieving its investment objective. The factors that may adversely affect the Fund’s correlation with the Index include, among others, the size of the Fund’s portfolio, fees, expenses, transaction costs, income items, valuation methodology, accounting standards, the effectiveness of sampling techniques (if applicable), changes in the Index and disruptions or illiquidity in the markets for the securities in which the Fund invests. While the Fund typically attempts to track the performance of the Index by investing all, or substantially all, of its assets in the securities that make up the Index in approximately the same proportion as their weighting in the Index, at times, the Fund may not have investment exposure to all securities in the Index, or its weighting of investment exposure to securities may be different from that of the Index. In addition, the Fund may invest in securities not included in the Index. The Fund may take or refrain from taking investment positions for various reasons, such as tax efficiency purposes, or to comply with regulatory restrictions, which may negatively affect the Fund’s correlation with the Index. The Fund may also be subject to large movements of assets into and out of the Fund, potentially resulting in the Fund being over- or under-exposed to certain components of the Index and may be impacted by Index reconstitutions and Index rebalancing events. Holding cash balances may detract from the Fund’s ability to track the Index. In addition, the Fund’s NAV may deviate from the Index if the Fund fair values a portfolio security at a price other than the price used by the Index for that security. The Fund also bears management and other expenses and transaction costs in trading securities or other instruments, which the Index does not bear. The Fund, unlike the Index, is subject to regulatory requirements that can limit the Fund’s investments relative to what the Index can hold. The Fund, unlike the Index, is subject to Office of Foreign Assets Control and other regulatory restrictions, including, for example, restrictions on the ability of the Fund to invest in or hold certain securities. If the Fund is restricted from investing in or holding a security or other instrument that was a component of the Index, and the Index did not remove such security or instrument, timely or at all, the Fund’s ability to track the Index could be negatively impacted. Accordingly, the Fund’s performance will likely fail to match the performance of the Index, after taking expenses into account, as well as regulatory restrictions. Any of these factors could decrease correlation between the performance of the Fund and the Index and may hinder the Fund’s ability to meet its investment objective. It is not possible to invest directly in an index.
The Fund is subject indirectly to the following risks of Portfolio Funds that are exchange-traded funds seeking investment results that, before fees and expenses, closely correspond to the performance of a stated index (the Index).
36
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Exchange-Traded Fund (ETF) Risk. ETFs are subject to, among other risks, tracking risk and passive and, in some cases, active investment risk. An ETF’s share price may not track its specified market index (if any) and may trade below its NAV. Certain ETFs use a “passive” investment strategy and do not take defensive positions in volatile or declining markets. Other ETFs are actively managed ETFs (i.e., they do not track a particular benchmark), which are subject to active management risk. An active secondary market in ETF shares may not develop or be maintained and may be halted or interrupted due to actions by its listing exchange, unusual market conditions or other reasons. There can be no assurance that an ETF’s shares will continue to be listed on an active exchange. In addition, shareholders bear their proportionate share of the Fund’s expenses and, indirectly, the ETF’s expenses incurred through ownership of the ETF. Because the expenses and costs of an underlying ETF are shared by its investors, redemptions by other investors in the ETF could result in decreased economies of scale and increased operating expenses for such ETF. These transactions might also result in higher brokerage, tax or other costs for the ETF. This risk may be particularly important when one investor owns a substantial portion of the ETF. There is a risk that ETFs in which the Fund invests may terminate due to extraordinary events. For example, any of the service providers to ETFs, such as the trustee or sponsor, may close or otherwise fail to perform their obligations to the ETF, and the ETF may not be able to find a substitute service provider. Also, certain ETFs may be dependent upon licenses to use various indexes as a basis for determining their compositions and/or otherwise to use certain trade names. If these licenses are terminated, the ETFs may also terminate. In addition, an ETF may terminate if its net assets fall below a certain amount.
Secondary Market Trading Risk. Investors buying or selling Fund shares will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of shares. In addition, secondary market investors will also incur the cost of the difference between the price that an investor is willing to pay for Fund shares (the bid price) and the price at which an investor is willing to sell Fund shares (the ask price). This difference in bid and ask prices is often referred to as the “spread” or “bid/ask spread.” The bid/ask spread varies over time for Fund shares based on trading volume and market liquidity, and is generally lower if the Fund’s shares have more trading volume and market liquidity and higher if the Fund’s shares have little trading volume and market liquidity. Further, increased market volatility may cause widening of bid/ask spreads.
Market Price Relative to NAV Risk. Shares of the Fund may trade at prices that vary from Fund NAV. Shares of the Fund are listed for trading on the Exchange (as defined in the Portfolio Fund’s prospectus) and are bought and sold in the secondary market at market prices that may differ, in some cases significantly, from their NAV. The NAV of the Fund will generally fluctuate with changes in the market value of the Fund’s holdings. The market prices of shares, however, will generally fluctuate in response to changes in NAV, as well as the relative supply of, and demand for, Fund shares on the Exchange. (as defined in the Portfolio Fund’s prospectus) The Investment Manager cannot predict whether Fund shares will trade below, at or above their NAV. Price differences may result because of, among other factors, supply and demand forces in the secondary trading market for Fund shares. It is expected that these forces generally will be closely related to, but not identical to, the same forces influencing the prices of the Fund’s holdings. In this regard, if a shareholder purchases Fund shares at a time when the market price is at a premium to the NAV or sells shares at a time when the market price is at a discount to the NAV, the shareholder may sustain losses. Different investment strategies or techniques, including those intended to be defensive in nature, including, as examples, stop loss orders to sell an ETF’s shares in the secondary market during negative market events or conditions, such as a “flash crash” or other market disruptions, may not work as intended and may produce significant losses to investors. Investors should consult their financial intermediary prior to using any such investment strategies or techniques, or before investing in the Fund.
Authorized Participant Concentration Risk. Only an Authorized Participant (as defined in the Portfolio Fund’s prospectus) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of institutions that may act as Authorized Participants, none of which are or will be obligated to engage in creation or redemption transactions. To the extent that these institutions exit the business or are unable or unwilling to proceed with creation and/or redemption orders with respect to the Fund and no other Authorized Participant is able or willing to step forward to create or redeem Creation Units(as defined in the Portfolio Fund’s prospectus), Fund shares may trade at a greater premium or discount between the market price and the NAV of the Fund’s shares and/or wider
Prospectus 2024
37

Columbia Thermostat FundSM
More Information About the Fund (continued)
bid/ask spreads than those experienced by other ETFs. Additionally, the Fund could possibly face trading halts and/or delisting from the Exchange. This risk is heightened in times of market stress, including at both the Fund share level and at the Fund holdings level.
Fund Shares Liquidity Risk. Although the Fund’s shares are listed on the Exchange, there can be no assurance that an active, liquid or otherwise orderly trading market for shares will be established or maintained by market makers or Authorized Participants, particularly in times of stressed market conditions. There is no guarantee that the Fund will be able to attract market makers and Authorized Participants. There is no obligation for market makers to make a market in the Fund’s shares or for Authorized Participants to submit purchase or redemption orders for creation units. Accordingly, if such parties determine not to perform their respective functions, this could, such as during times of market stress, in turn, lead to variances between the market price of the Fund’s shares and the underlying value of those shares and bid/ask spreads could widen. Trading in Fund shares on the Exchange also may be disrupted or even halted due to market conditions or for reasons that, in the view of the Exchange, make trading in Fund shares inadvisable. In addition, trading in Fund shares on the Exchange may be subject to trading halts caused by extraordinary market volatility pursuant to the Exchange “circuit breaker” rules. There also can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund’s shares will continue to be met or will remain unchanged.
Early/Late Close/Trading Halt Risk.  An exchange or market may close early, close late or issue trading halts on specific securities, or the ability to buy or sell certain securities may be restricted, which may result in the Fund being unable to buy or sell these securities. In these circumstances, the Fund may be unable to rebalance and/or reconstitute its portfolio (as applicable), may be unable to accurately price its investments, may incur substantial trading losses and/or may be prevented from sufficiently tracking the performance of the Index.
Additional Investment Strategies and Policies
This section describes certain investment strategies and policies that the Fund may utilize in pursuit of its investment objective and some additional factors and risks involved with investing in the Fund. For information about risks associated with changing levels of Fund distributions, see the SAI.
Changing the Fund’s Investment Objective and Policies
The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Board without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the SAI, may be changed only with Board and shareholder approval in accordance with the voting requirements of the 1940 Act. For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see the SAI.
Investment Guidelines
As a general matter, and except as specifically described in the discussion of the Fund's principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund's assets that may be invested in any security or other asset or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined based on the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.
Holding Other Kinds of Investments
The Fund may hold other investments that are not part of its principal investment strategies. These investments and their risks are described below and/or in the SAI. The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so. Information on the Fund’s holdings can be found in the Fund’s shareholder reports or by visiting columbiathreadneedleus.com.
Transactions in Derivatives
The Fund may enter into derivative transactions or otherwise have exposure to derivative transactions through underlying investments. The Fund expects to enter into such transactions primarily in the form of stock index futures in order to obtain exposure to the overall sector of the market represented by a particular stock index or to invest the
38
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Fund’s uninvested cash balances in a manner that the Investment Manager believes aligns more closely with the Fund’s investment strategy than simply holding short-term fixed income investments or cash equivalents (known as cash equitization). Derivatives are financial contracts whose values are, for example, based on (or “derived” from) traditional securities (such as a stock or bond), assets (such as a commodity like gold or a foreign currency), reference rates (such as the Secured Overnight Financing Rate (commonly known as SOFR)) or market indices (such as the Standard & Poor’s 500® Index). The use of derivatives is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. Derivatives involve special risks and may result in losses or may limit the Fund’s potential gain from favorable market movements. Derivative strategies typically expose the Fund to gains and losses in excess of the amount actually invested in the derivative. This characteristic of a derivative (known as "leverage") may exaggerate a loss, potentially causing the Fund to lose more money than it would have lost had it invested in the underlying security or other asset directly. The values of derivatives may move in unexpected ways, especially in unusual (including distressed) market conditions, and may result in increased volatility in the value of the derivative and/or the Fund’s shares, among other consequences.  The use of derivatives may also increase the amount of taxes payable by shareholders holding shares in a taxable account. Other risks arise from the Fund’s potential inability to terminate or to sell derivative positions. A liquid secondary market may not always exist for the Fund’s derivative positions at times when the Fund might wish to terminate or to sell such positions. Over-the-counter instruments (investments not traded on an exchange) may be illiquid, and transactions in derivatives traded in the over-the-counter market are subject to the risk that the other party will not meet its obligations. The use of derivatives also involves the risks of mispricing or improper valuation and that changes in the value of the derivative may not correlate perfectly with the underlying security, asset, reference rate or index. The Fund also may not be able to find a suitable derivative transaction counterparty, and thus may be unable to engage in derivative transactions when it is deemed favorable to do so, or at all. U.S. federal legislation has been enacted that provides for new clearing, margin, reporting and registration requirements for participants in the derivatives market. These changes could restrict and/or impose significant costs or other burdens upon the Fund’s participation in derivatives transactions. The U.S. government and the European Union (and some other jurisdictions) have enacted regulations and similar requirements that prescribe clearing, margin, reporting and registration requirements for participants in the derivatives market. These requirements are evolving and their ultimate impact on the Fund remains unclear, but such impact could include restricting and/or imposing significant costs or other burdens upon the Fund’s participation in derivatives transactions. Additionally, regulations governing the use of derivatives by registered investment companies, such as the Fund, require, among other things, that a fund that invests in derivative instruments beyond a specified limited amount to apply a value-at-risk-based limit to its portfolio and establish a comprehensive derivatives risk management program. As of the date of this prospectus, the Fund is not required to maintain a comprehensive derivatives risk management program given its more limited use of derivatives. For more information on the risks of derivative investments and strategies, see the SAI.
Affiliated Fund Investing
The Investment Manager and its affiliate, Columbia Management Investment Advisers, LLC (Columbia Management), serve as investment advisers to mutual funds and ETFs using the Columbia brand (Columbia Funds), including mutual funds that are structured as “fund-of-funds”, and provides asset-allocation services to (i) shareholders by investing in shares of other Columbia Funds (collectively referred to in this section as Portfolio Funds), and (ii) discretionary managed accounts (collectively referred to as affiliated products) that invest exclusively in Portfolio Funds. These affiliated products, individually or collectively, may own a significant percentage of the outstanding shares of one or more Portfolio Funds, and the Investment Manager and Columbia Management seek to balance potential conflicts of interest between the affiliated products and the Portfolio Funds in which they invest. The affiliated products’ investment in the Portfolio Funds may have the effect of creating economies of scale, possibly resulting in lower expense ratios for the Portfolio Funds, because the affiliated products may own substantial portions of the shares of Portfolio Funds. However, redemption of Portfolio Fund shares by one or more affiliated products could cause the expense ratio of the Portfolio Fund to increase, as its fixed costs would be spread over a smaller asset base. Because of large positions of certain affiliated products, the Portfolio Funds may experience relatively large inflows and outflows of cash due to affiliated products’ purchases and sales of Portfolio Fund shares. Although the
Prospectus 2024
39

Columbia Thermostat FundSM
More Information About the Fund (continued)
Investment Manager or Columbia Management may seek to minimize the impact of these transactions where possible, for example, by structuring them over a reasonable period of time or through other measures, Portfolio Funds may experience increased expenses as they buy and sell portfolio securities to manage the cash flow effect related to these transactions. Further, when the Investment Manager or Columbia Management structures transactions over a reasonable period of time in order to manage the potential impact of the buy and sell decisions for the affiliated products, those affiliated products, including funds-of-funds, may pay more or less (for purchase activity), or receive more or less (for redemption activity), for shares of the Portfolio Funds than if the transactions were executed in one transaction. In addition, substantial redemptions by affiliated products within a short period of time could require the Portfolio Fund to liquidate positions more rapidly than would otherwise be desirable, which may have the effect of reducing or eliminating potential gain or causing it to realize a loss. In order to meet such redemptions, the Portfolio Fund may be forced to sell its liquid (or more liquid) positions, leaving the Portfolio Fund holding, post-redemption, a relatively larger position in illiquid investments (i.e., any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment) or less liquid securities. Substantial redemptions may also adversely affect the ability of the Portfolio Fund to implement its investment strategy. The Investment Manager or Columbia Management also has a conflict of interest in determining the allocation of affiliated products’ assets among the Portfolio Funds, as it earns different fees from the various Portfolio Funds.
Investing in Money Market Funds
The Fund may invest cash, including cash collateral received in connection with its securities lending program, in shares of money market funds, including funds advised by affiliates of the Investment Manager. These funds are not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. The Fund and its shareholders indirectly bear a portion of the expenses of any money market fund or other fund in which the Fund may invest.
Investing Defensively
The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political, social or other conditions. These investment positions may include, without limitation, investing some or all of its assets in money market instruments or shares of affiliated or unaffiliated money market funds or holding some or all of its assets in cash or cash equivalents. The Fund may take such defensive investment positions for as long a period as the Investment Manager deems necessary. During these times, the Investment Manager may make frequent portfolio changes, which could result in increased trading expenses and taxes, and decreased Fund performance.
Portfolio Holdings Disclosure
A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, columbiathreadneedleus.com, as described below. Once posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or publicly available Form N-PORT (forms filed with the SEC that include portfolio holdings information) for the period that includes the date as of which the information is current.
The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed approximately 30 to 40 days after each month-end. The top 15 holdings may be available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current.
Cybersecurity
The Fund, like all companies, may be susceptible to operational and information security risks, including the risk of cyber attacks or failures. As a result, the Fund or its service providers, or the issuers of securities in which the Fund invests, may experience disruptions in business operations that may potentially result in financial losses, the inability
40
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
of the Fund or Fund shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, and/or additional compliance costs. The Fund and its shareholders could be negatively impacted as a result. See the discussion of Cybersecurity Breaches and Technology and Related Systems Failure Risk in the SAI for further information.
Use of Benchmarks
Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmark(s) it believes provide meaningful comparisons for the Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmark(s) may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.
FUNDamentals
Portfolio Holdings Versus the Benchmarks
The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund's holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund's weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.
eDelivery and Mailings to Households
In order to reduce shareholder expenses, the Fund may mail only one copy of the Fund’s prospectus and each annual and semiannual report to those addresses shared by two or more accounts. If you wish to receive separate copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly. Additionally, you may elect to enroll in eDelivery to receive electronic versions of these documents, as well as quarterly statements and supplements, by logging into your account at columbiathreadneedleus.com/investor/.
Additional Information on Portfolio Turnover
Because Columbia Thermostat Fund is a fund-of-funds that exchanges shares of the Portfolio Funds at net asset value, the costs associated with the Fund’s portfolio turnover rate are lower than the costs that would be associated with another fund that had the same portfolio turnover rate but directly bore the trading costs of its portfolio transactions. See the Financial Highlights section of this prospectus for the Fund's portfolio turnover rates for the past five years.
Cash Flows
The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to shareholders redeeming Fund shares could require the Fund to sell portfolio securities at less than opportune times or to hold ready reserves of uninvested cash in amounts larger than might otherwise be the case to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.
Understanding Annual Fund Operating Expenses
The Fund’s annual operating expenses, as presented in the Annual Fund Operating Expenses table in the Fees and Expenses of the Fund section of this prospectus, generally are based on expenses incurred during the Fund’s most recently completed fiscal year, may vary by share class and are expressed as a percentage (expense ratio) of the Fund’s average net assets during that fiscal year. The expense ratios reflect the Fund’s fee arrangements as of the date of this prospectus and, unless indicated otherwise, are based on expenses incurred during the Fund’s most recent fiscal year. The Fund’s assets will fluctuate, but unless indicated otherwise in the Annual Fund Operating Expenses table, no adjustments have been or will be made to the expense ratios to reflect any differences in the
Prospectus 2024
41

Columbia Thermostat FundSM
More Information About the Fund (continued)
Fund’s average net assets between the most recently completed fiscal year and the date of this prospectus or a later date. In general, the Fund’s expense ratios will increase as its net assets decrease, such that the Fund’s actual expense ratios may be higher than the expense ratios presented in the Annual Fund Operating Expenses table if assets fall. Any commitment by the Investment Manager and/or its affiliates to waive fees and/or cap (reimburse) expenses is expected, in part, to limit the impact of any increase in the Fund’s expense ratios that would otherwise result because of a decrease in the Fund’s assets in the current fiscal year. The Fund’s annual operating expenses are comprised of (i) investment management fees, (ii) distribution and/or service fees, and (iii) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Please see Fee Waiver/Expense Reimbursement Arrangements below for information about commitments made by the Investment Manager and/or its affiliates during the performance period covered by this prospectus.
FUNDamentals
Other Expenses
“Other expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are allocated on a pro rata basis across all share classes. These expenses include certain sub-transfer agency and shareholder servicing fees. Transfer agency fees and certain shareholder servicing fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “other expenses” among share classes are primarily the result of the different transfer agency and shareholder servicing fees applicable to each share class. For more information on these fees, see Choosing a Share Class — Financial Intermediary Compensation.
Fee Waiver/Expense Reimbursement Arrangements
The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies, including the Portfolio Funds (acquired funds)) do not exceed the annual rates shown below through April 30, 2025. This arrangement may only be amended or terminated with approval from the Board and the Investment Manager.
The effective expense ratio for the Fund, gross of the contractual waiver/reimbursement discussed above, will vary in connection with the changes to the Portfolio Funds and to the allocation of the Fund’s assets among the Portfolio Funds, which the Investment Manager may make to from time to time, as described above under Principal Investment Strategies.
Columbia Thermostat Fund
Class A
0.50%
Class Adv
0.25%
Class C
1.25%
Class Inst
0.25%
Class Inst2
0.20%
Class Inst3
0.16%
Class S
0.25%
The fee waivers and/or expense reimbursements shown in the table above also reflect the contractual agreement of the Fund's Transfer Agent to waive a portion of its fees through April 30, 2025, such that the Fund's transfer agency fees do not exceed the annual rates of 0.04% of the average daily net assets of Class Inst2 shares and 0.00% of the average daily net assets of Class Inst3 shares. This arrangement may be terminated at the sole discretion of the Board.
42
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or its affiliates that were in place during the performance period shown in the Performance Information section of this prospectus. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.
Board of Trustees
The Fund is governed by the Board. More than 75% of the Fund's Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund's officers to establish the Fund's policies and oversee its activities. Among the Trustees' responsibilities are: selecting the investment adviser for the Fund; approving the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.
Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust's Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on February 27, 2015. Any Trustee may be removed at a shareholders' meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 71 S. Wacker Drive, Suite 2500, Chicago, Illinois 60606.
For more detailed information about the Board, please refer to the SAI.
Primary Service Provider Contracts
The Fund enters into contractual arrangements (Service Provider Contracts) with various parties, including, among others, the Investment Manager, the Distributor, the Transfer Agent and the Fund’s custodian. The Fund’s Service Provider Contracts are solely among the parties thereto. Shareholders are not parties to, or intended to be third-party beneficiaries of, any Service Provider Contracts. Further, this prospectus, the SAI and any Service Provider Contracts are not intended to give rise to any agreement, duty, special relationship or other obligation between the Fund and any investor, or give rise to any contractual, tort or other rights in any individual shareholder, group of shareholders or other person, including any right to assert a fiduciary or other duty, enforce the Service Provider Contracts against the parties or to seek any remedy thereunder, either directly or on behalf of the Fund. Nothing in the previous sentence should be read to suggest any waiver of any rights under federal or state securities laws.
The Investment Manager, which also serves as the Fund's administrator (the Administrator), Columbia Management, which serves as the Fund's sub-administrator pursuant to an agreement with the Investment Manager (the Sub-Administrator), the Distributor, and the Transfer Agent are all affiliates of Ameriprise Financial. They and their affiliates currently provide key services, including investment advisory, administration, distribution, shareholder servicing and transfer agency services, to the Fund and various other funds, including the Columbia Funds, and are paid for providing these services. These service relationships are described below.
The Investment Manager
Columbia Wanger Asset Management, LLC is located at 71 S. Wacker Drive, Suite 2500, Chicago, Illinois 60606. As of March 31, 2024, the Investment Manager had assets under management of approximately $6.5 billion. The Investment Manager is a registered investment adviser and wholly-owned subsidiary of Columbia Management, which is a wholly-owned subsidiary of Ameriprise Financial. In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other private funds and institutional accounts.
Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing portfolio transactions. The Investment Manager may use the research and other capabilities of its affiliates and third parties in managing the Fund’s investments.
Prospectus 2024
43

Columbia Thermostat FundSM
More Information About the Fund (continued)
The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate fees paid to the Investment Manager by the Fund amounted to 0.10% of average daily net assets of the Fund, before any applicable reimbursements.
A discussion regarding the basis for the Board’s approval of the renewal of the Fund’s investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2023.
The Investment Manager and its investment advisory affiliates, including Columbia Management and Threadneedle International Limited (Threadneedle) (Participating Affiliates), around the world may coordinate in providing services to their clients. From time to time, the Investment Manager may engage its Participating Affiliates to provide a variety of services such as investment research, investment monitoring, trading, and discretionary investment management (including portfolio management and proxy voting) to certain accounts managed by the Investment Manager, including the Fund. These Participating Affiliates will provide services to the Fund and other accounts of the Investment Manager either pursuant to delegation agreements, personnel-sharing agreements or similar inter-company or other arrangements or relationships and the Fund will pay no additional fees and expenses as a result of any such arrangements or relationships. These Participating Affiliates, like the Investment Manager, are direct or indirect subsidiaries of Ameriprise Financial and are registered with the appropriate respective regulators in their home jurisdictions and, where required, the SEC and the Commodity Futures Trading Commission in the United States.
Pursuant to some of these arrangements or relationships, certain personnel of Columbia Management and other Participating Affiliates serve as “associated persons” or officers of the Investment Manager and, in this capacity, subject to the oversight and supervision of the Investment Manager and consistent with the investment objectives, policies and limitations set forth in this prospectus and the Fund’s SAI, and with the Investment Manager’s and the Fund’s compliance policies and procedures, provide services to the Fund.
Portfolio Managers
Information about the portfolio managers primarily responsible for overseeing the Fund’s investments is shown below. The SAI provides additional information about the portfolio managers, including information relating to compensation, other accounts managed by the portfolio managers, and ownership by the portfolio managers of Fund shares.
Portfolio Management
Title
Role with Fund
Service with the Fund Since
Alex M. Rivas
Portfolio Manager of Columbia
Management and Vice President of the
Investment Manager
Portfolio Manager
since 2022
2018
Corey Lorenzen, CFA
Portfolio Manager of Columbia
Management and Vice President of the
Investment Manager
Portfolio Manager
since 2023
2023
Mr. Rivas joined Columbia Management, an affiliate of the Investment Manager, in 2017. Mr. Rivas has served as Assistant Vice President of the Investment Manager since February 2018. Mr. Rivas began his investment career in 2009 and earned a B.S. from Georgia Institute of Technology and a Master in Finance degree from Princeton University.
Mr. Lorenzen joined Columbia Management, an affiliate of the Investment Manager, in 2012. Mr. Lorenzen began his investment career in 2012 and earned a B.S. from the University of Wisconsin - Madison and an M.S. from the University of Wisconsin - Milwaukee.
The Administrator
Columbia Wanger Asset Management, LLC is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator retains the Sub-Administrator to perform many of these services (including fund accounting), and pays a fee for the services of the
44
Prospectus 2024

Columbia Thermostat FundSM
More Information About the Fund (continued)
Sub-Administrator. The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:
Annual Administration Fee, as a % of Aggregate Daily Net Assets of the Trust:
Up to $8 billion
0.050%
$8 billion to $16 billion
0.040%
$16 billion to $35 billion
0.030%
$35 billion to $45 billion
0.025%
$45 billion and over
0.015%
The Distributor
Shares of the Fund are distributed by Columbia Management Investment Distributors, Inc., which is located at 290 Congress Street, Boston, MA 02210. The Distributor is a registered broker-dealer and an indirect, wholly-owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.
The Transfer Agent
Columbia Management Investment Services Corp. is a registered transfer agent and wholly-owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 290 Congress Street, Boston, MA 02210, and its responsibilities include processing purchases, redemptions and exchanges of Fund shares, calculating and paying distributions, maintaining shareholder records, preparing account statements and providing customer service. The Transfer Agent has engaged SS&C GIDS, Inc. to provide various shareholder or “sub-transfer agency” services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares, pursuant to which the Transfer Agent pays these financial intermediaries for providing certain shareholder services. Depending on the type of account, the Fund pays the Transfer Agent a per account fee for each open account and compensates the Transfer Agent for certain out-of-pocket expenses, including certain payments to financial intermediaries through which shares are held. In addition, subject to certain limitations, the Fund compensates the Transfer Agent for payments made to financial intermediaries for the shareholder services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of shareholder services provided. The Transfer Agent is contractually obligated to oversee such intermediaries for the purpose of reasonably assuring their compliance with applicable law and the terms of their agreements to provide the shareholder services. For more information about Shareholder Services fees, see Choosing a Share Class — Financial Inte