485BPOS

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund

Investment Objective

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, to financial intermediaries, which are not reflected in the table and example below. If such expenses were reflected, the expenses set forth below would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Management fees^(a)	0.23%
Distribution and/or service (12b-1) fees	0.00%
Other expenses	0.00%
Total annual Fund operating expenses	0.23%

(a)

Pursuant to the Investment Management Services Agreement with Columbia ETF Trust I on behalf of the Fund, Columbia Management Investment Advisers, LLC pays the operating costs and expenses of the Fund, but not taxes, interest, brokerage expenses, portfolio transaction expenses, and infrequent and/or unusual expenses.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated (whether or not shares are redeemed), and assumes that:

■	you invest $10,000 in the Fund 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.

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
	$24	$74	$130	$293

Portfolio Turnover

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund 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 14% of the average value of its portfolio.

Principal Investment Strategies

The Fund is an exchange-traded fund (ETF) that seeks to track the performance of the Index. The Fund invests at least 80% of its assets in securities within the Index. For purposes of this policy, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes) in bonds and other debt instruments issued by or on behalf of state or local governmental units whose interest is exempt from U.S. federal income tax. In addition, the Fund may invest in cash, cash equivalents and money market instruments, such as money market funds (including money market funds advised by Columbia Management Investment Advisers, LLC (Columbia Management or the Investment Manager)), that the Investment Manager believes will help the Fund track the performance of the Index.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

The Index is owned and calculated by Bloomberg Index Services Limited (Bloomberg or the Index Provider), which is not affiliated with the Fund or Columbia Management. The Index was developed by Columbia Management working with the Index Provider.

Beta Advantage^® Multi-Sector Approach to U.S. Municipal Debt Market Investing. The Index reflects a rules-based, multi-sector strategic beta approach to measuring the performance of the U.S tax-exempt bond market, which is composed of bonds issued by or on behalf of state or local governments whose interest is exempt from regular federal income tax (but may be subject to the alternative minimum tax), through representation of five segments of the municipal debt market in the Index, with a focus on yield, quality, maturity, liquidity, and interest rate sensitivity of the particular segment. The Index includes publicly issued U.S. dollar denominated, fixed rate municipal bonds. California bonds, Guam bonds, Puerto Rico bonds, U.S. Virgin Island bonds, other U.S. territories, commonwealths and possessions, pre-refunded bonds, insured bonds, floaters, callable bonds with less than 1 year to call, tobacco bonds, and derivatives are all excluded from the Index.

The Index, and therefore the Fund, will have exposure to the following five segments of the municipal debt market (% amount noted is the Index’s allocation to the particular segment at Index rebalancing and reconstitution, as described below): the Municipal Core Revenue Segment, as described below (45%); health care-related debt – the Municipal Health Care Segment (20%); high quality revenue bonds – the Municipal High Quality Revenue Segment (15%); general obligation (GO) bonds – the Municipal Core GO Segment (10%); and high yield debt (also known as “junk bonds”) – the Municipal High Yield Segment (10%). Each of the five Segment’s component bonds, other than the Municipal High Yield Segment, is derived from a sub-set index or indices of the Bloomberg Barclays Municipal Bond Index (the Parent Index), which serves as each segment’s starting universe of securities eligible for inclusion in the Index. The Parent Index is a broad-based, market value-weighted index designed to measure the performance of the U.S. municipal bond market. The Index is designed to achieve higher yields and stronger risk-adjusted returns relative to that of the Parent Index. The Index’s allocation to each of the five segments of the municipal debt market, represented by five sub-index models is fixed as of each Index rebalancing and reconstitution, but may vary due to the performance of each segment between these events. The number of securities in each of the five sub-index models and the Index as a whole noted below are as of January 31, 2023 and may change over time. The five sub-index models, each as discussed below, will generate all of the component securities of the Index. Each sub-index model, as well as the Index itself, is market-value weighted.

Beta Advantage^® Strategy to Investing in the Municipal Core Revenue Segment. As part of its multi-sector approach, the Index holds, and therefore the Fund invests in, those securities included in: the Bloomberg Barclays Municipal Bond: Electric Index, the Bloomberg Barclays Municipal Bond: Transportation Index, the Bloomberg Barclays Municipal Bond: Education Index, and the Bloomberg Barclays Municipal Bond: Leasing Index that meet the following criteria: are rated Aa3 or lower; have a remaining maturity of between and including 5 and 15 years; have an outstanding par value of at least $10 million for the Bloomberg Barclays Municipal Bond: Leasing Index, $15 million for the Bloomberg Barclays Municipal Bond: Electric Index and the Bloomberg Barclays Municipal Bond: Education Index, and $30 million for the Bloomberg Barclays Municipal Bond: Transportation Index; and were issued as part of a transaction of at least $100 million. At January 31, 2023, this sub-index model held 1,598 securities.

Beta Advantage^® Strategy to Investing in the Municipal Health Care Segment. As part of its multi-sector approach, the Index holds, and therefore the Fund invests in, those securities included in the Bloomberg Barclays Municipal Bond: Hospital Index that meet the following criteria: are rated Aa2 or lower; have a remaining maturity of between and including 10 and 25 years; have an outstanding par value of at least $10 million; and were issued as part of a transaction of at least $100 million. At January 31, 2023, this sub-index model held 1,476 securities.

Beta Advantage^® Strategy to Investing in the Municipal High Quality Revenue Segment. As part of its multi-sector approach, the Index holds, and therefore the Fund invests in, those securities included in the: (i) Bloomberg Barclays Municipal Bond: Housing Index that meet the following criteria: are rated Aa2 or higher; have a remaining maturity of between and including 2 and 15 years; have an outstanding par value of at least $10 million; and were issued as part of a transaction of at least $100 million; and (ii) the Bloomberg Barclays Municipal Bond: Water & Sewer Index that meet the following criteria: are rated A2 or higher; have a remaining maturity of between and including 2 and 10 years; have an outstanding par value of at least $15 million; and were issued as part of a transaction of at least $100 million. At January 31, 2023, this sub-index model held 825 securities.

4	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

Beta Advantage^® Strategy to Investing in the Municipal Core GO Segment. As part of its multi-sector approach, the Index holds, and therefore the Fund invests in, those securities included in the Bloomberg Barclays Municipal Bond: GO Index that meet the following criteria: are rated Aa3 or higher; have a remaining maturity of between and including 2 and 10 years; have an outstanding par value of at least $15 million for local GO bonds and $25 million for state GO bonds; and were issued as part of a transaction of at least $100 million. At January 31, 2023, this sub-index model held 1,752 securities.

Beta Advantage^® Strategy to Investing in the Municipal High Yield Segment. As part of its multi-sector approach, the Index holds, and therefore the Fund invests in, those securities included in the Bloomberg Barclays Municipal High Yield Bond Index that meet the following criteria: are rated B3 or higher; have a remaining maturity of between and including 10 and 25 years; have an outstanding par value of at least $5 million; and were issued as part of a transaction of at least $25 million. Tobacco bonds are excluded from this sector. At January 31, 2023, this sub-index model held 476 securities.

All credit rating designations noted above are according to Bloomberg Barclays’ index rating methodology.

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 Index (as well as the sub-index models) are 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.

As noted above, the five sub-index models will generate all of the component securities of the Index. Columbia Management expects to utilize a “representative sampling” strategy whereby the Fund invests in only some of the component securities of the Index that, collectively, are believed by the Investment Manager to generally reflect the same risk and return characteristics of the Index. As such, the Fund may not track the Index with the same degree of accuracy as would a fund replicating (or investing in) the entire Index. Through its representative sampling investment technique, the Fund expects to typically hold 650-750 holdings, which is a subset of the total number of holdings in the Index, which, as of January 31, 2023, had 6,127 holdings. There may be instances in which the Fund may overweight (or underweight) an Index holding, 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 track the performance of the 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 Index.

The Fund may sell securities or other holdings that are represented in the 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.

The Investment Manager 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 Index regardless of market conditions and does not take defensive positions.

To the extent the Index is concentrated in a particular segment, sector or industry, the Fund will be concentrated in that segment, sector or industry.

Principal Risks

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

significance of any specific risk to an investment in the Fund will vary over time depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information below carefully, because any one or more of these risks may result in losses to the Fund.

Authorized Participant Concentration Risk. Only an Authorized Participant (as defined below) 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, 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 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.

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.

Correlation/Tracking Error Risk. The 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. By using a representative sampling approach, the Fund may not track the Index as closely as it would by using a full replication approach. In addition, the Fund 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. Accordingly, the Fund’s performance will likely fail to match the performance of the Index, after taking expenses into account, as well as regulatory limitations. It is not possible to invest directly in an index.

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.

Credit Risk. Credit risk is the risk that the value of 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. Debt instruments backed by an issuer's taxing authority may be subject to legal limits on the issuer's power to increase taxes or otherwise to raise revenue, or may be dependent on legislative appropriation or government aid. Certain debt instruments are backed only by revenues derived from a particular project or source, rather than by an issuer's taxing authority, and thus may have a greater risk of default. Credit rating agencies, such as S&P Global Ratings, Moody’s Investors Service, Inc. (Moody’s), Fitch Ratings, Inc. (Fitch), DBRS Morningstar (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.

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 reconstitute its portfolio, 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.

6	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

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.

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 expose the Fund to a greater risk of loss of principal and income than a fund that invests solely or primarily in investment grade debt instruments. In addition, these investments have greater price fluctuations, are less liquid and are 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.

Index Methodology and Provider Risk. The 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 not follow its stated methodology for construction or errors may be made in Index computation, construction and reconstitution, as applicable, despite any Index Provider procedures designed to prevent such occurrences and due diligence conducted by the Investment Manager. Errors may result in a negative performance impact to the Fund and its shareholders. The decision of whether to remove a security from the tracking index is made by an independent index provider who is not affiliated with the Fund or the Investment Manager.

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 debt instruments tend to fall, and if interest rates fall, the values of 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. Very low or negative interest rates may impact the Fund’s yield and may increase the risk that, if followed by rising interest rates, the Fund’s performance will be negatively impacted. 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. 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.

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.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

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 of creation units, which may negatively impact Fund performance and NAV, including, for example, if the Fund is forced to sell investments in a down market. In certain circumstances, the Fund might not be able to dispose of certain holdings quickly or at fair prices, preventing the Fund from tracking the Index. The municipal securities market is an over-the-counter market, which means that the Fund purchases and sells investments through municipal bond dealers. The Fund’s ability to sell investments held in its portfolio is dependent on the willingness and ability of market participants to provide bids that, in the view of portfolio management, reflect current market prices. Adverse market conditions could result in a lack of liquidity by reducing the number of ready buyers. In addition, in stressed market conditions, the market for Fund shares may become less liquid. Deterioration in the liquidity of Fund shares may adversely impact the liquidity of the Fund's underlying portfolio securities. These adverse impacts on the liquidity of Fund shares and on the liquidity of the Fund's underlying portfolio securities could in turn lead to a greater premium or discount between the market price and the NAV of the Fund's shares and/or wider bid/ask spreads than those experienced by other ETFs.

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 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. 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.

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

8	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

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 and could result in a greater premium or discount between the market price and the NAV of the Fund's shares and/or wider bid/ask spreads than those experienced by other ETFs.

Money Market Fund Investment Risk. An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the FDIC or any other government agency. Certain money market funds float their NAV while others seek to preserve the value of investments at a stable NAV (typically, $1.00 per share). An investment in a money market fund, even an investment in a fund seeking to maintain a stable NAV per share, is not guaranteed and it is possible for the Fund to lose money by investing in these and other types of money market funds. If the liquidity of a money market fund’s portfolio deteriorates below certain levels, the money market fund may suspend redemptions (i.e., impose a redemption gate) and thereby prevent the Fund from selling its investment in the money market fund or impose a fee of up to 2% on amounts the Fund redeems from the money market fund (i.e., impose a liquidity fee). These measures may result in an investment loss or prohibit the Fund from redeeming shares when the Investment Manager would otherwise redeem shares. In addition to the fees and expenses that the Fund directly bears, the Fund indirectly bears the fees and expenses of any money market funds in which it invests, including affiliated money market funds. By investing in a money market fund, the Fund will be exposed to the investment risks of the money market fund in direct proportion to such investment. To the extent the Fund invests in instruments such as derivatives, the Fund may hold investments, which may be significant, in money market fund shares to cover its obligations resulting from the Fund’s investments in such instruments. Money market funds and the securities they invest in are subject to comprehensive regulations. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operation, performance and/or yield of money market funds.

Issuers in a state, territory, commonwealth or possession in which the Fund invests may experience significant financial difficulties for various reasons, including as the result of events that cannot be reasonably anticipated or controlled such as economic downturns or similar periods of economic stress, social conflict or unrest, labor disruption and natural disasters. Such financial difficulties may lead to credit rating downgrades or defaults of such issuers which in turn, could affect the market values and marketability of many or all municipal obligations of issuers in such state, territory, commonwealth or possession. The value of the Fund’s shares will be negatively impacted to the extent it invests in such securities. The Fund’s annual and semiannual reports show the Fund’s investment exposures at a point in time. The risk of investing in the Fund is directly correlated to the Fund’s investment exposures.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

Securities issued by a particular state and its instrumentalities are subject to the risk of unfavorable developments in such state. A municipal security can be significantly affected by adverse tax, legislative, regulatory, demographic or political changes as well as changes in a particular state's (state and its instrumentalities) financial, economic or other condition and prospects.

The Fund’s investments in municipal securities may include securities of issuers in the electric, transportation, education, and leasing sectors (collectively, these sectors compose the Municipal Core Revenue Sector), which subjects the Fund’s investments to the risks associated with those sectors, including the risk of regulatory action or policy changes by numerous governmental agencies and bodies, including federal, state, and local governmental agencies, as well as requirements imposed by private entities. Issuers in the Municipal Core Revenue Sector are subject to certain risks, including competitive pricing pressures, the rising cost of products and services (especially for companies dependent upon a relatively limited number of products or services) among others, government regulation, obtaining and protecting patents (or the failure to do so), product liability and other similar litigation, labor disputes, lease supply and demand, and technology obsolescence, amongst other factors and conditions.

The Fund’s investments in municipal securities may include securities of issuers in the health care sector, which subjects the Fund’s investments to the risks associated with that sector, including the risk of regulatory action or policy changes by numerous governmental agencies and bodies, including federal, state, and local governmental agencies, as well as requirements imposed by private entities, such as insurance companies. A major source of revenue for the health care industry is payments from the Medicare and Medicaid programs. As a result, the industry is sensitive to legislative changes and reductions in governmental spending for such programs. Numerous other factors may affect the industry, such as general and local economic conditions, demand for services, expenses (including, among others, malpractice insurance premiums) and competition among health care providers. Additional factors also may adversely affect health care facility operations, such as adoption of legislation proposing a national health insurance program, other state or local health care reform measures, medical and technological advances that alter the need for or cost of health services or the way in which such services are delivered, changes in medical coverage that alter the traditional fee-for-service revenue stream, and efforts by employers, insurers, and governmental agencies to reduce the costs of health insurance and health care services.

Passive Investment Risk. The Fund is not actively managed and may be affected by a general decline in market segments related to its Index’s investment exposures. The Fund invests in securities or instruments included in, or believed by the Investment Manager to be representative of the Index regardless of their investment merits. The Fund does not seek temporary defensive positions when markets decline or appear overvalued.

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. In the case of mortgage- or other asset-backed securities, as interest rates decrease or spreads narrow, the likelihood of prepayment increases. Conversely, extension risk is the risk that an unexpected rise in interest rates will extend the life of a mortgage- or other asset-backed 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.

10	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

particular time. 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.

Tax Risk. Municipal securities generally pay interest that, in the opinion of bond counsel, is free from U.S. federal income tax (and in most cases, the U.S. federal alternative minimum tax). A portion of the Fund’s income from such bonds may be taxable to shareholders subject to the U.S. federal alternative minimum tax. Income from tax-exempt municipal obligations could be declared taxable, possibly retroactively, because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service, the non-compliant conduct of a bond issuer or under other circumstances. In such event, then the value of the security would likely fall and, as a shareholder of the Fund, you may be required to file an amended tax return and pay additional taxes.

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.

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. The bar chart shows how the Fund’s 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 the index the Fund seeks to track, which provides a broad measure of market performance, as well as another measure of performance for markets in which the Fund may invest.

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).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

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 800.426.3750 or visiting columbiathreadneedleus.com/etfs.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

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	_{4th Quarter 2022}	_4.21%
	_Worst	_{1st Quarter 2022}	_-6.66%

Average Annual Total Returns (for periods ended December 31, 2022)

	Inception Date	1 Year	Life of Fund
At NAV	10/10/2018
returns before taxes		-8.67%	2.33%
returns after taxes on distributions		-9.32%	1.45%
returns after taxes on distributions and sale of Fund shares		-5.13%	1.43%
Beta Advantage® Multi-Sector Municipal Bond Index (reflects no deductions for fees, expenses or taxes)		-8.46%	2.21%
Bloomberg Municipal Bond Index (reflects no deductions for fees, expenses or taxes)		-8.53%	1.74%

Fund Management

Investment Manager: Columbia Management Investment Advisers, LLC

Portfolio Management	Title	Role with Fund	Managed Fund Since
Catherine Stienstra	Senior Portfolio Manager and Head of Municipal Bond Investments	Lead Portfolio Manager	2018
Douglas Rangel, CFA	Senior Portfolio Manager	Portfolio Manager	June 2022
William (Bill) L. Callagy	Portfolio Manager	Portfolio Manager	June 2022

Purchase and Sale of Fund Shares

The Fund issues and redeems shares only through Authorized Participants (intermediaries, typically broker-dealers who have executed an agreement with the Fund's distributor that governs transactions in Fund creation units) in large blocks of shares, typically 50,000 shares, called Creation Units. Creation Units are issued and redeemed typically for an in-kind basket of securities. Except when aggregated in Creation Units, the Fund shares are not redeemable securities of the Fund.

Individual shares may only be purchased and sold on secondary markets through a financial intermediary, such as a broker-dealer or a bank. Because the Fund’s shares trade at market prices rather than NAV, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). You may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase shares of the ETF (bid) and the lowest price a seller is willing to accept for shares of the ETF (ask) when buying or selling shares in the secondary market (the bid/ask spread). Recent information, including information regarding the Fund’s NAV, market price, premiums and discounts, and bid/ask spread, is available at columbiathreadneedleus.com/etfs.

12	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Summary of the Fund (continued)

Tax Information

Generally, a substantial portion of the Fund’s distributions consists of exempt-interest dividends, which are generally not taxable to you for U.S. federal income tax purposes or for purposes of the U.S. federal alternative minimum tax. A portion of the Fund’s distributions may not qualify as exempt-interest dividends; such distributions will generally be 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. 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 shares through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies 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. Ask your financial advisor or visit your financial intermediary’s website for more information.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund

Investment Objective

Columbia Multi-Sector Municipal Income ETF (the Fund) seeks investment results that, before fees and expenses, closely correspond to the performance of the Beta Advantage^® Multi-Sector Municipal Bond Index (the Index). The Fund’s investment objective is not a fundamental policy and may be changed by the Fund’s Board of Trustees without shareholder approval. Because any investment involves risk, there is no assurance the Fund’s investment objective will be achieved.

Principal Investment Strategies

14	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

for the Bloomberg Barclays Municipal Bond: Electric Index and the Bloomberg Barclays Municipal Bond: Education Index, and $30 million for the Bloomberg Barclays Municipal Bond: Transportation Index; and were issued as part of a transaction of at least $100 million. At January 31, 2023, this sub-index model held 1,598 securities.

All credit rating designations noted above are according to Bloomberg Barclays’ index rating methodology.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

To the extent the Index is concentrated in a particular segment, sector or industry, the Fund will be concentrated in that segment, sector or industry.

The Fund’s investment policy with respect to 80% of its assets may be changed by the Fund’s Board of Trustees without shareholder approval as long as shareholders are given 60 days’ advance written notice of the change. Additionally, shareholders will be given 60 days' advance written notice of a change to the Fund’s investment objective if such a change is made in connection with the SEC rule governing fund names.

Principal Risks

An investment in the Fund involves risks, including Interest Rate Risk, Credit Risk, Market Risk, Municipal Securities Risk, Passive Investment Risk, and Correlation/Tracking Error Risk, among others. Descriptions of these and other principal risks of investing in the Fund are provided below. 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. The significance of any specific risk to an investment in the Fund will vary over time depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information below carefully, because any one or more of these risks may result in losses to the Fund.

Correlation/Tracking Error Risk. The 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, changes in the Index and disruptions or illiquidity in the markets for the securities or other instruments in which the Fund invests. The Fund uses a “representative sampling” approach in seeking to track the performance of the Index, which is an indexing strategy that involves investing in only some of the components of the Index that collectively are believed to have an investment profile similar to that of the Index. Because the Fund uses a representative sampling approach, the Fund may not track the Index with the same degree of accuracy as would an

16	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

investment vehicle replicating the entire Index. In addition, the Fund may invest in securities or other instruments 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 that was a component of the Index, and the Index did not remove such security, 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 limitations. 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.

Counterparty Risk. The risk exists that a counterparty to a transaction in a financial instrument held by the Fund or by a special purpose or structured vehicle in which the Fund invests may become insolvent or otherwise fail to perform its obligations, including making payments to the Fund, due to financial difficulties. The Fund may obtain no or limited recovery in a bankruptcy or other reorganizational proceedings, and any recovery may be significantly delayed. Transactions that the Fund enters into may involve counterparties in the financial services sector and, as a result, events affecting the financial services sector may cause the Fund’s share value to fluctuate.

Credit Risk. Credit risk is the risk that the value of 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. Debt instruments backed by an issuer's taxing authority may be subject to legal limits on the issuer's power to increase taxes or otherwise to raise revenue, or may be dependent on legislative appropriation or government aid. Certain debt instruments are backed only by revenues derived from a particular project or source, rather than by an issuer's taxing authority, and thus may have a greater risk of default. Credit rating agencies, such as S&P Global Ratings, Moody’s, Fitch, DBRS and 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.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

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.

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 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.

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 debt instruments tend to fall, and if interest rates fall, the values of 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). Very low or negative interest rates may impact the Fund’s yield and may increase the risk that, if followed by rising interest rates, the Fund’s performance will be negatively impacted. 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. 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.

18	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

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 of creation units, which may negatively impact Fund performance and NAV, including, for example, if the Fund is forced to sell investments in a down market. In certain circumstances, the Fund might not be able to dispose of certain holdings quickly or at fair prices, preventing the Fund from tracking the Index. The municipal securities market is an over-the-counter market, which means that the Fund purchases and sells investments through municipal bond dealers. The Fund’s ability to sell investments held in its portfolio is dependent on the willingness and ability of market participants to provide bids that, in the view of portfolio management, reflect current market prices. Adverse market conditions could result in a lack of liquidity by reducing the number of ready buyers. In addition, in stressed market conditions, the market for Fund shares may become less liquid. Deterioration in the liquidity of Fund shares may adversely impact the liquidity of the Fund's underlying portfolio securities. These adverse impacts on the liquidity of Fund shares and on the liquidity of the Fund's underlying portfolio securities could in turn lead to a greater premium or discount between the market price and the NAV of the Fund's shares and/or wider bid/ask spreads than those experienced by other ETFs.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

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 and could result in a greater premium or discount between the market price and the NAV of the Fund's shares and/or wider bid/ask spreads than those experienced by other ETFs.

The pandemic caused by coronavirus disease 2019 and its variants (COVID-19) has resulted in, and may continue to result in, significant global economic and societal disruption and market volatility due to disruptions in market access, resource availability, facilities operations, imposition of tariffs, export controls and supply chain disruption, among others. Such disruptions may be caused, or exacerbated by, quarantines and travel restrictions, workforce displacement and loss in human and other resources. The uncertainty surrounding the magnitude, duration, reach, costs and effects of the global pandemic, as well as actions that have been or could be taken by governmental authorities or other third parties, present unknowns that are yet to unfold. The impacts, as well as the uncertainty over impacts to come, of COVID-19 – and any other infectious illness outbreaks, epidemics and pandemics that may arise in the future – could negatively affect global economies and markets in ways that cannot necessarily be foreseen. In addition, the impact of infectious illness outbreaks and epidemics in less developed countries may be greater due to generally less established healthcare systems, governments and financial markets. Public health crises caused by the COVID-19 outbreak may exacerbate other pre-existing political, social and economic risks in certain countries or globally. The disruptions caused by COVID-19 could prevent the Fund from executing advantageous investment decisions in a timely manner and negatively impact the Fund’s ability to achieve its investment objective. Any such events could have a significant adverse impact on the value and risk profile of the Fund.

Money Market Fund Investment Risk. An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the FDIC or any other government agency. Certain money market funds float their NAV while others seek to preserve the value of investments at a stable NAV (typically $1.00 per share). An investment in a money market fund, even an investment in a fund seeking to maintain a stable NAV per share, is not guaranteed and it is possible for the Fund to lose money by investing in these and other types of money market funds. If the liquidity of a money market fund’s portfolio deteriorates below certain levels, the money market fund may suspend redemptions (i.e., impose a redemption gate) and thereby prevent the Fund from selling its investment in the money market fund or impose a fee of up to 2% on amounts the Fund redeems from the money market fund (i.e., impose a liquidity fee). These measures may result in an investment loss or prohibit the Fund from redeeming shares when the Investment Manager would otherwise redeem shares. In addition to the fees and expenses that the Fund directly bears, the Fund indirectly bears the fees and expenses of any money market funds in which it invests, including affiliated money market funds. To the extent these fees and expenses, along with the fees and expenses of any other funds in which the Fund may invest, are expected to equal or exceed 0.01% of the Fund’s average daily net assets, they will be reflected in the Annual Fund Operating Expenses set forth in the table under “Fees and Expenses of the Fund.” By investing in a money market fund, the Fund will be exposed to the investment risks of the money market fund in direct proportion to such investment. The money market fund may not achieve its investment objective. The Fund, through its investment in the money market fund, may not achieve its investment objective. To the extent the Fund invests in instruments such as derivatives, the Fund may hold investments, which may be significant, in money market fund shares to cover its obligations resulting from the Fund’s investments in such instruments. Money market funds and the securities they invest in are subject to comprehensive regulations. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operation, performance and/or yield of money market funds.

20	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

Municipal Securities Risk. Municipal securities are debt obligations generally issued to obtain funds for various public purposes, including general financing for state and local governments, or financing for a specific project or public facility, and include obligations of the governments of the U.S. territories, commonwealths and possessions such as Guam, Puerto Rico and the U.S. Virgin Islands to the extent such obligations are exempt from state and U.S. federal income taxes. The value of municipal securities can be significantly affected by actual or expected political and legislative changes at the federal or state level. Municipal securities may be fully or partially backed by the taxing authority of the local government, by the credit of a private issuer, by the current or anticipated revenues from a specific project or specific assets or by domestic or foreign entities providing credit support, such as letters of credit, guarantees or insurance, and are generally classified into general obligation bonds and special revenue obligations. General obligation bonds are backed by an issuer's taxing authority and may be vulnerable to limits on a government's power or ability to raise revenue or increase taxes. They may also depend for payment on legislative appropriation and/or funding or other support from other governmental bodies. Revenue obligations are payable from revenues generated by a particular project or other revenue source, and are typically subject to greater risk of default than general obligation bonds because investors can look only to the revenue generated by the project or other revenue source backing the project, rather than to the general taxing authority of the state or local government issuer of the obligations. Because many municipal securities are issued to finance projects in sectors such as education, health care, transportation and utilities, conditions in those sectors can affect the overall municipal market. The amount of publicly available information for municipal issuers is generally less than for corporate issuers.

Issuers in a state, territory, commonwealth or possession in which the Fund invests may experience significant financial difficulties for various reasons, including as the result of events that cannot be reasonably anticipated or controlled such as economic downturns or similar periods of economic stress, social conflict or unrest, labor disruption and natural disasters. Such financial difficulties may lead to credit rating downgrades or defaults of such issuers which, in turn, could affect the market values and marketability of many or all municipal obligations of issuers in such state, territory, commonwealth or possession. The value of the Fund’s shares will be negatively impacted to the extent it invests in such securities. The Fund’s annual and semiannual reports show the Fund’s investment exposures at a point in time. The risk of investing in the Fund is directly correlated to the Fund’s investment exposures.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

alter the need for or cost of health services or the way in which such services are delivered, changes in medical coverage that alter the traditional fee-for-service revenue stream, and efforts by employers, insurers, and governmental agencies to reduce the costs of health insurance and health care services.

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. In the case of mortgage- or other asset-backed securities, as interest rates decrease or spreads narrow, the likelihood of prepayment increases. Conversely, extension risk is the risk that an unexpected rise in interest rates will extend the life of a mortgage- or other asset-backed 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.

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 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.

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.

22	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

adverse interpretations by the Internal Revenue Service, the non-compliant conduct of a bond issuer or under other circumstances. In such event, then the value of the security would likely fall and, as a shareholder of the Fund, you may be required to file an amended tax return and pay additional taxes.

How the Fund Differs from Traditional Mutual Funds

Redeemability. Traditional mutual fund shares may be bought from, and redeemed with, the issuing fund for cash at NAV typically calculated once at the end of each business day. Shares of an ETF, by contrast, cannot be purchased from or redeemed with the ETF except by or through Authorized Participants, and then typically for an in-kind basket of securities. Except when aggregated in Creation Units, the Fund shares are not redeemable securities of the Fund. In addition, ETFs issue and redeem shares on a continuous basis only in large blocks of shares, typically 50,000 shares (which is the case for the Fund), called Creation Units.

Exchange Listing. Unlike traditional mutual fund shares, the Fund’s shares are listed for trading on the Exchange. Investors can purchase and sell shares on the secondary market through a broker or other financial intermediary (collectively, financial intermediary(ies)). There can be no assurance that the Fund's shares will continue to trade on the Exchange or that the Fund's shares will continue to meet the requirements for listing or trading on the Exchange. Investors purchasing shares in the secondary market through a brokerage account or with the assistance of a financial intermediary may be subject to brokerage commissions and charges. Secondary-market transactions do not occur at NAV, but at market prices that change throughout the day, based on the supply of, and demand for, shares and on changes in the prices of the Fund’s portfolio holdings. The market price of shares may differ from the NAV of the Fund. The difference between market price of shares and the NAV of the Fund is called a premium when the market price is above the reported NAV and called a discount when the market price is below the reported NAV. The market price of the Fund's shares may deviate significantly from the NAV of the shares, for example, in times of extreme market volatility or other conditions.

Tax Treatment. The Fund’s structure may provide for enhanced tax efficiency relative to a traditional mutual fund’s structure. Specifically, to the extent the Fund redeems its shares in kind, the distribution of portfolio securities to meet such redemption requests may mitigate certain adverse tax consequences associated with traditional mutual fund shares to continuing Fund shareholders. This is because traditional mutual funds typically sell portfolio securities to obtain cash to meet redemptions and, as necessary, may recognize taxable gains in connection with such sales. By contrast, to the extent the Fund redeems its shares in kind, as opposed to in cash, the Fund’s in-kind redemption mechanism will potentially reduce, relative to a traditional mutual fund, taxable gains resulting from redemptions. However, the Fund cannot predict to what extent, if any, it will redeem its shares in kind rather than in cash, particularly during the Fund’s growth stages when portfolio changes are more likely to be implemented within the Fund rather than through the in-kind redemption mechanism. Nor can the Fund predict the extent to which any such in-kind redemptions will reduce the taxable gain recognized in connection therewith.

ETFs generally are able to make in-kind redemptions and avoid being taxed on gain on the distributed portfolio securities at the Fund level. Because the Fund may effect redemptions partly or entirely in cash, rather than in-kind distributions, it may be required to sell portfolio securities in order to obtain the cash needed to distribute redemption proceeds. If the Fund recognizes gain on these sales, this generally will cause the Fund to recognize gain it might not otherwise have recognized, or to recognize such gain sooner than would otherwise be required if it were to distribute portfolio securities in-kind. The Fund generally intends to distribute these gains to shareholders to avoid being taxed on this gain at the Fund level and otherwise comply with the special tax rules that apply to it. This strategy may cause shareholders to be subject to tax on gains they would not otherwise be subject to, or at an earlier date than, if they had made an investment in a different ETF. Moreover, cash transactions may have to be carried out

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

over several days if the securities market is relatively illiquid and may involve considerable brokerage fees and taxes. These brokerage fees and taxes, which will be higher than if the Fund sold and redeemed its shares principally in-kind, will be passed on to purchasers and redeemers of Creation Units in the form of creation and redemption transaction fees.

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.

The Fund may consider changing the Index at any time, including if, for example: the Index becomes unavailable; the Board believes that the Index no longer serves shareholder investment needs or that another index may better serve their needs; or the financial or economic environment makes it difficult for the Fund’s investment results to correspond sufficiently to the Index. If the Fund determines to change the Index, it will assess the appropriateness of the Fund's current name in light of the new index.

20% Asset Policy

In addition to any instruments mentioned in the Fund’s principal investment strategies, the Fund may invest up to 20% of its net assets in derivatives, including forward contracts (including forward foreign currency contracts), futures (including equity futures and index futures), options (including options on futures) and swaps (including portfolio and total return swaps), as well as cash, cash equivalents and money market instruments, such as repurchase agreements and money market funds (including affiliated money market funds) for the purpose of seeking to assist the Fund in tracking the performance of the Index.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund's principal investment strategies in this prospectus or as otherwise required by the Investment Company Act of 1940, as amended (the 1940 Act), the rules and regulations thereunder and any applicable exemptive relief, 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 solely at the time of the Fund's investment in the security or asset.

Holding Other Kinds of Investments

The Fund may hold other investments that are not part of its principal investment strategies but that are for the purpose of seeking to assist the Fund in tracking the performance of the Index. 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/etfs.

Transactions in Derivatives

The Fund may enter into derivative transactions. 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 the London Interbank Offered Rate (commonly known as LIBOR)) 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 often involve leverage, which 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 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

24	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

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, in October 2020, the SEC adopted new regulations governing the use of derivatives by registered investment companies. Rule 18f-4, among other things, requires 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 under Rule 18f-4 given its more limited use of derivatives. For more information on the risks of derivative investments and strategies, see the SAI.

Affiliated Funds Investing in the Fund

The Investment Manager or an affiliate serves as investment adviser to funds using the Columbia brand (Columbia Funds), including those that are structured as “fund-of-funds”, and provides asset-allocation services to (i) shareholders by investing in shares of other Columbia Funds, which may include the Fund (collectively referred to in this section as Underlying Funds), and (ii) discretionary managed accounts (collectively referred to as affiliated products) that invest exclusively in Underlying Funds. These affiliated products, individually or collectively, may own a significant percentage of the outstanding shares of one or more Underlying Funds, and the Investment Manager seeks to balance potential conflicts of interest between the affiliated products and the Underlying Funds in which they invest. The affiliated products’ investment in the Underlying Funds may have the effect of creating economies of scale, possibly resulting in lower expense ratios for the Underlying Funds, because the affiliated products may own substantial portions of the shares of Underlying Funds. However, redemption of Underlying Fund shares by one or more affiliated products could cause the expense ratio of an Underlying Fund to increase, as its fixed costs would be spread over a smaller asset base. Because of large positions of certain affiliated products, the Underlying Funds may experience relatively large inflows and outflows of cash due to affiliated products’ purchases and sales of Underlying Fund shares. Although the Investment Manager or its affiliate 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, Underlying 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 its affiliate 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 Underlying 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 Underlying 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, an Underlying Fund may be forced to sell its liquid (or more liquid) positions, leaving the Underlying 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 Underlying Fund to implement its investment strategy. The Investment Manager or its affiliate also has a conflict of interest in determining the allocation of affiliated products’ assets among the Underlying Funds, as it earns different fees from the various Underlying Funds.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

Investing in Money Market Funds

The Fund may invest cash in, or hold as collateral for certain investments, shares of registered or unregistered money market funds, including funds advised by the Investment Manager or its affiliates. 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.

Fund Website and Disclosure of Portfolio Holdings

Information about the Fund may be found at columbiathreadneedleus.com/etfs. Among other things, this website includes the Summary Prospectus, this prospectus and the SAI, the Fund’s annual and semiannual reports and information on the Fund’s net asset value, market price, premiums/discounts, and bid-ask spreads, among other information.

Each day the Fund is open for business, it publicly disseminates the Fund’s full portfolio holdings as of the close of the previous business day through its website at columbiathreadneedleus.com/etfs. In addition, the In-Kind Creation Basket and In-Kind Redemption Basket, which identify the securities and share quantities which may be delivered in exchange for purchases and redemptions of Creation Units as discussed below and in the SAI, are publicly disseminated each business day prior to the opening of trading on the Exchange via the National Securities Clearing Corporation (NSCC).

Additional Information on Portfolio Turnover

A fund that replaces, or turns over, more than 100% of its investments in a year may be considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. Also, a high portfolio turnover rate can mean higher brokerage commissions and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact that brokerage commissions and other transaction costs will have on its returns. The Fund may sell securities regardless of how long they’ve been held. A higher portfolio turnover rate may reduce the relative potential tax efficiency of the Fund compared with traditional mutual funds except potentially in cases where accomplished through redemptions in kind. You'll find the Fund's portfolio turnover rate for its most recent fiscal period in the Fees and Expenses of the Fund — Portfolio Turnover section of this prospectus and portfolio turnover rates for the past five years or since inception, if the Fund has been in operation for less than five years, in the Financial Highlights section of this prospectus.

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 and are expressed as a percentage (expense ratio) of the Fund’s average net assets during that fiscal year. The expense ratio reflects the Fund’s fee arrangements as of the date of this prospectus and, unless indicated otherwise, is 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 ratio to reflect any differences in the Fund’s average net assets between the most recently completed fiscal year and the date of this prospectus or a later date. As applicable, 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 ratio 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. No distribution or service fees are currently paid by the Fund, and there are no current plans to impose these fees.

26	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

Primary Service Provider Contracts

The Fund enters into contractual arrangements (Service Provider Contracts) with various service providers, including, among others, the Investment Manager, the administrator, 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

Columbia Management Investment Advisers, LLC is located at 290 Congress Street, Boston, MA 02210 and serves as investment adviser to the Columbia Funds, including the Fund. The Investment Manager is a registered investment adviser and a wholly-owned subsidiary of Ameriprise Financial, Inc. (Ameriprise Financial). The Investment Manager’s management experience covers all major asset classes, including equity securities, debt instruments and money market instruments. In addition to serving as an investment adviser to traditional mutual funds, exchange-traded funds and closed-end funds, the Investment Manager acts as an investment adviser for itself, its affiliates, individuals, corporations, retirement plans, private investment companies and financial intermediaries.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund. The Investment Manager has entered into a license agreement with Bloomberg to use the Beta Advantage^® Multi-Sector Municipal Bond Index, as Bloomberg is the owner of the Index. The Fund is permitted to use the Index pursuant to a sub-licensing agreement with the Investment Manager.

The SEC has issued an order that permits the Investment Manager, subject to the approval of the Board, to appoint affiliated and unaffiliated subadvisers by entering into subadvisory agreements with them, and to change in material respects the terms of those subadvisory agreements, including the fees paid thereunder, for the Fund without first obtaining shareholder approval, thereby avoiding the expense and delays typically associated with obtaining shareholder approval. The Fund furnishes shareholders with information about new subadvisers retained in reliance on the order within 90 days after hiring the subadviser. The Investment Manager and its affiliates may have other relationships, including significant financial relationships, with current or potential subadvisers or their affiliates, which may create certain conflicts of interest. When making recommendations to the Board to appoint or to change a subadviser, or to change the terms of a subadvisory agreement, the Investment Manager discloses to the Board the nature of any such material relationships. The SEC has issued a separate order that permits the Board to approve new subadvisory agreements or material changes to existing subadvisory agreements at a meeting that is not in person, provided that the Trustees are able to participate in the meeting using a means of communication that allows them to hear each other simultaneously during the meeting and other conditions of the order are satisfied. At present, the Investment Manager has not engaged any investment subadviser for the Fund.

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. In return for this fee (which is sometimes referred to as a unitary or unified fee), the Investment Manager has agreed to pay the operating costs and expenses of the Fund other than the following expenses, which will be paid by the Fund: taxes, interest incurred on borrowing by the Fund, if any, brokerage fees and commissions, interest and fee expense related to the Fund’s participation in inverse floater structures and any other portfolio transaction expenses, infrequent and/or unusual expenses, including without limitation litigation expenses, distribution and/or service fees, expenses incurred in connection with lending securities, and any other expenses approved by the Board. For the Fund’s most recent fiscal year, investment advisory services fees paid to the Investment Manager by the Fund amounted to 0.23% of average daily net assets of the Fund, before any applicable reimbursements.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

A discussion regarding the basis for the Board’s approval of the renewal of the investment management services agreement with the Investment Manager is available in the Fund’s annual report to shareholders for the fiscal year ended October 31, 2022.

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	Managed Fund Since
Catherine Stienstra	Senior Portfolio Manager and Head of Municipal Bond Investments	Lead Portfolio Manager	2018
Douglas Rangel, CFA	Senior Portfolio Manager	Portfolio Manager	June 2022
William (Bill) L. Callagy	Portfolio Manager	Portfolio Manager	June 2022

Ms. Stienstra joined the Investment Manager in 2007 as a senior portfolio manager. Ms. Stienstra began her investment career in 1988 and earned a B.A. from the University of Nebraska.

Mr. Rangel joined the Investment Manager in 2019. Prior to joining the Investment Manager, he was a senior director for client portfolio management at Galliard Capital Management, a wholly-owned subsidiary of Wells Fargo. Mr. Rangel began his investment career in 2000 and earned a B.A. in Business Management from Greenville University and an M.B.A. from the University of St. Thomas.

Mr. Callagy joined the Investment Manager in 2017. Mr. Callagy began his investment career in 2008 and earned a B.S. from Fairfield University.

Other Service Providers

ALPS Distributors, Inc. (the Distributor), 1290 Broadway, Suite 1100, Denver, CO 80203, serves as the distributor of Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in shares.

BNY Mellon Corporation (BNY Mellon), 240 Greenwich Street, New York, NY 10286, is the administrator, fund accountant, transfer agent and custodian for the Fund.

PricewaterhouseCoopers LLP, 45 South Seventh Street, Suite 3400, Minneapolis, MN 55402, serves as the Fund’s independent registered public accounting firm. The independent registered public accounting firm is responsible for auditing the annual financial statements of the Fund.

Index Provider

Bloomberg Index Services Limited, with offices at 731 Lexington Avenue, New York, NY 10022, is the owner and calculator of the Beta Advantage^® Multi-Sector Municipal Bond Index.

Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest

The Investment Manager provides various services to the Fund and other Columbia Funds for which it is compensated. Ameriprise Financial and its affiliates may also provide other services to these funds and be compensated for them.

The Investment Manager and its affiliates may provide investment advisory and other services to other clients and customers substantially similar to those provided to the Columbia Funds. These activities, and other financial services activities of Ameriprise Financial and its affiliates, may present actual and potential conflicts of interest and introduce certain investment constraints.

28	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

More Information About the Fund (continued)

Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the fund-related activities of the Investment Manager, including, among others, insurance, broker-dealer (sales and trading), asset management, banking and other financial activities. These additional activities may involve multiple advisory, financial, insurance and other interests in securities and other instruments, and in companies that issue securities and other instruments, that may be bought, sold or held by the Columbia Funds.

Conflicts of interest and limitations that could affect a Columbia Fund may arise from, for example, the following:

■	compensation and other benefits received by the Investment Manager and other Ameriprise Financial affiliates related to the management/administration of a Columbia Fund and the sale of its shares;

■	the allocation of, and competition for, investment opportunities among the Fund, other funds and accounts advised/managed by the Investment Manager and other Ameriprise Financial affiliates, or Ameriprise Financial itself and its affiliates;

■	separate and potentially divergent management of a Columbia Fund and other funds and accounts advised/managed by the Investment Manager and other Ameriprise Financial affiliates;

■	regulatory and other investment restrictions on investment activities of the Investment Manager and other Ameriprise Financial affiliates and accounts advised/managed by them;

■	insurance and other relationships of Ameriprise Financial affiliates with companies and other entities in which a Columbia Fund invests; and

■	regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, and a Columbia Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Management and Other Services — Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest section of the SAI. Investors in the Columbia Funds should carefully review these disclosures and consult with their financial advisor if they have any questions.

Certain Legal Matters

Ameriprise Financial and certain of its affiliates are involved in the normal course of business in legal proceedings which include regulatory inquiries, arbitration and litigation, including class actions concerning matters arising in connection with the conduct of its activities as a diversified financial services firm. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make quarterly (10-Q), annual (10-K) and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at sec.gov.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Buying and Selling Fund Shares

Shares are issued or redeemed by the Fund at NAV per share only in Creation Units of 50,000 shares. As of December 31, 2022, the value of one Creation Unit of the Fund was $1,006,864.08.

Shares trade on the secondary market, which is where most retail investors will buy and sell shares. It is expected that only a limited number of institutional investors will purchase and redeem shares directly from the Fund. Thus, certain information in this prospectus is not relevant to most retail investors. For example, information about buying and redeeming Creation Units directly from the Fund and about transaction fees imposed on such purchases and redemptions is not relevant to most retail investors.

Except when aggregated in Creation Units, the Fund’s shares are not redeemable with the Fund. Additional information about the procedures regarding creation and redemption of Creation Units (including the cut-off times for receipt of creation and redemption orders) is included in the SAI.

Buying and Selling Fund Shares on the Secondary Market

The Fund issues or redeems its shares at NAV per share only in Creation Units and only to Authorized Participants (or APs). Most investors will buy and sell shares in secondary market transactions through brokers or other financial intermediaries, and therefore must have an account with them to buy and sell shares. Shares can be bought or sold through your financial intermediary throughout the trading day like shares of any publicly traded issuer. When buying or selling shares through a financial intermediary, you will incur customary brokerage commissions and charges, and you may pay some or all of the spread between the bid and the offered prices in the secondary market for shares. The price at which you buy or sell shares (i.e., the market price) may be more (a premium to) or less than (a discount to) the NAV of the shares. Unless imposed by your financial intermediary, there is no minimum dollar amount you must invest in the Fund and no minimum number of shares you must buy. The Fund accommodates frequent purchases and redemptions of Creation Units by Authorized Participants and does not place a limit on purchases or redemptions of Creation Units by these investors. The Fund reserves the right, but does not have the obligation, to reject any purchase or redemption transaction at any time.

Shares of the Fund are listed on the Exchange under the symbol: MUST

The Exchange is generally open Monday through Friday and is closed for weekends and the following holidays: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day.

For information about buying and selling shares on the Exchange or in the secondary markets, please contact your financial intermediary.

Book Entry. Shares are held in book entry form, which means that no stock certificates are issued. The Depository Trust Company (DTC), or its nominee, is the registered owner of all outstanding shares of the Fund and is recognized as the owner of all shares. Participants in DTC include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of shares, you are not entitled to receive physical delivery of Fund Shares certificates or to have shares registered in your name, and you are not considered a registered owner of shares. Therefore, to exercise any right as an owner of shares, you must rely on the procedures of DTC and its participants. These procedures are the same as those that apply to any stocks that you hold in book entry or “street name” through your brokerage account. Your account information will be maintained by your financial intermediary, which will provide you with account statements, confirmations of your purchases and sales of shares, and tax information. Your financial intermediary also will be responsible for distributing income dividends and capital gain distributions and for ensuring that you receive shareholder reports and other communications from the Fund.

Share Trading Prices. The trading prices of the Fund’s shares may differ from the Fund’s daily NAV and can be affected by market forces of supply and demand for the Fund’s shares, the prices of the Fund’s investments, economic conditions and other factors. The Exchange or another market information provider intends to disseminate the approximate value of the Fund’s portfolio every fifteen seconds. This approximate value should not be viewed as a “real-time” update of the NAV of the Fund because the approximate value may not be calculated in the same manner as the NAV, which is computed once a day. The quotations for certain investments may not be updated during

30	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Buying and Selling Fund Shares (continued)

U.S. trading hours if such holdings do not trade in the U.S., except such quotations may be updated to reflect currency fluctuations. The Fund is not involved in, or responsible for, the calculation or dissemination of the approximate values and makes no warranty as to the accuracy of these values.

Additional Information About Buying and Selling Fund Shares

Continuous Offering. Authorized Participants should be aware of certain legal risks unique to investors purchasing Creation Units directly from the Fund. Because shares may be issued on an ongoing basis, a “distribution” of shares could be occurring at any time. Certain activities that Authorized Participants perform with respect to the sale of shares could, depending on the circumstances, result in Authorized Participants being deemed to be a participant in the distribution, in a manner that could render Authorized Participants a statutory underwriter and subject Authorized Participants to the prospectus delivery and liability provisions of the Securities Act. For example, Authorized Participants could be deemed a statutory underwriter if Authorized Participants purchase Creation Units from the issuing Fund, break them down into the constituent shares, and sell those shares directly to customers, or if Authorized Participants choose to couple the creation of a supply of new shares with an active selling effort involving solicitation of secondary market demand for shares. Whether a person is an underwriter for purposes of the Securities Act depends upon all of the facts and circumstances pertaining to that person’s activities, and the examples mentioned here should not be considered a complete description of all the activities that could cause Authorized Participants to be deemed an underwriter.

Broker-dealer firms should also note that dealers who are not “underwriters” but are effecting transactions in shares, whether or not participating in the distribution of shares, are generally required to deliver a prospectus. This is because the prospectus delivery exemption in Section 4(3) of the Securities Act is not available in respect of such transactions as a result of Section 24(d) of the 1940 Act. As a result, broker-dealer firms should note that dealers who are not “underwriters” but are participating in a distribution (as opposed to engaging in ordinary secondary market transactions), and thus dealing with shares as part of an unsold allotment within the meaning of Section 4(3)(C) of the Securities Act, will be unable to take advantage of the prospectus delivery exemption provided by Section 4(3) of the Securities Act. For delivery of prospectuses to exchange members, the prospectus delivery mechanism of Rule 153 under the Securities Act is only available with respect to transactions on a national exchange.

Active Investors and Market Timing

The Board has determined not to adopt policies and procedures designed to prevent or monitor for frequent purchases and redemptions of the Fund’s shares because investors primarily transact in Fund shares on the secondary market. Frequent trading of shares on the secondary market does not disrupt portfolio management, increase the Fund’s trading costs, lead to realization of capital gains or otherwise harm Fund shareholders because these trades do not involve the issuance or redemption of Fund shares.

The Fund sells and redeems its shares at NAV only in Creation Units pursuant to the terms of a Participant Agreement between an Authorized Participant and the Distributor, and accepted by the Transfer Agent. With respect to such trades directly with the Fund to the extent effected in-kind (i.e., for securities), they generally would not cause the harmful effects that may result from frequent cash trades.

The Board recognizes that to the extent that the Fund allows or requires trades to be effected in whole or in part in cash, those trades could result in dilution to a Fund and increased transaction costs, which could negatively impact the Fund’s ability to achieve its investment objective. The Board also recognizes, however, that direct trading by Authorized Participants is critical to ensuring that the Fund’s shares trade at or close to NAV. Further, the Fund may employ fair valuation pricing to minimize the potential for dilution. Moreover, the Fund imposes transaction fees on purchases and redemptions of Creation Units reflecting the fact that the Fund’s costs increase in those circumstances. The Fund reserves the right to impose additional restrictions on disruptive, excessive or short-term purchases.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Buying and Selling Fund Shares (continued)

Distribution and Service Fees

The Board has approved, and the Fund has adopted, a distribution and service plan (the Plan) pursuant to Rule 12b-1 under the 1940 Act. Under the Plan, the Fund is authorized to pay distribution fees to the Distributor and other firms that provide distribution and shareholder services (Service Providers). If a Service Provider provides such services, the Fund may pay fees at an annual rate not to exceed 0.25% of average daily net assets, pursuant to Rule 12b-1 under the 1940 Act.

No distribution or service fees are currently paid by the Fund, and there are no current plans to impose these fees. Future payments may be made under the Plan without any further shareholder approval. In the event Rule 12b-1 fees are charged, over time they would increase the cost of an investment in the Fund.

Determination of Net Asset Value

FUNDamentals

NAV Calculation

The Fund calculates its NAV as follows:

NAV = (Value of assets) – (Liabilities)
Number of outstanding shares

FUNDamentals

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day typically ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE is scheduled to close early, the business day will be considered to end as of the time of the NYSE’s scheduled close. For purposes of this section only, the Fund will not treat an intraday unscheduled disruption in NYSE trading or an intraday unscheduled closing as a close of regular trading on the NYSE for these purposes and will price its shares as of the regularly scheduled closing time for that day (typically, 4:00 p.m. Eastern time). Notwithstanding the foregoing, the NAV of Fund shares may be determined at such other time or times (in addition to or in lieu of the time set forth above) as the Fund’s Board may approve or ratify. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities listed on an exchange are typically valued at the closing price or last trade on their primary exchange at the close of business of the NYSE. Securities without a readily available closing price or that are not listed on any exchange are typically valued at the mean between the closing bid and asked prices. Other equity securities, debt securities and other assets are valued differently. For instance, bank loans trading in the secondary market are fair valued unless market quotations are readily available, fixed income investments maturing in 60 days or less are valued primarily using the amortized cost method, unless this methodology results in a valuation that does not approximate the market value of these securities, and those maturing in excess of 60 days are valued based on prices obtained from a pricing service, if available (which may represent market values or fair values). Investments in other open-end funds are valued at their published NAVs. The value of each Fund’s portfolio securities is determined in accordance with the valuation policy approved by the Board.

If a market price is not readily available or is deemed not to reflect market value, the Investment Manager will determine the price of a portfolio security based on a determination of the security's fair value pursuant to the valuation policy approved by the Fund's Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund's share price is calculated. Foreign exchanges typically close before the time at which Fund

32	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Buying and Selling Fund Shares (continued)

share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria in determining whether a foreign security's market price is readily available and reflective of market value and, if not, the fair value of the security.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Investment Manager uses fair valuation to price equity securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund's performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund's performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Distributions and Taxes

Distributions to Shareholders

A fund can make money two ways:

■	It can earn income on its investments. Examples of fund income are interest paid on money market instruments and dividends paid on common stocks.

■

A fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is generally unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than its adjusted cost basis, and will generally realize a capital loss if it sells that investment for a lower price than its adjusted cost basis. Capital gains and losses are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term) or more than one year (long-term).

Funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund's distributed income, including capital gains. Reinvesting your distributions buys you more shares of a fund — which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money (or be exposed to additional losses, if the fund earns a negative return). Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you'll earn more money if you reinvest your distributions rather than receive them in cash.

Brokers may make available to their customers who own shares the DTC book-entry dividend reinvestment service. To determine whether the dividend reinvestment service is available and whether there is a commission or other charge for using this service, consult your broker. Brokers may require Fund shareholders to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and net realized gains will be automatically reinvested in additional whole shares of the distributing Fund purchased in the secondary market. Without this service, investors would receive their distributions in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal income or excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule
Declarations	Monthly
Distributions	Monthly

The Fund may declare or pay distributions of net investment income more frequently.

Each time a distribution is made, the NAV per share is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared. If you sell all of your shares after the record date, but before the payment date, for a distribution, you'll normally receive that distribution in cash within five business days after the sale was made.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund's distribution schedule, which is available at the Funds' website and/or by calling 800.426.3750.

34	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Distributions and Taxes (continued)

Taxes

You should be aware of the following considerations applicable to the Fund:

■

The Fund intends to qualify and to be eligible for treatment each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund's failure to qualify for treatment as a regulated investment company would result in Fund-level taxation, and consequently, a reduction in income available for distribution to you and in the NAV of your shares. Even if the Fund qualifies for treatment as a regulated investment company, the Fund may be subject to federal excise tax on certain undistributed income or gains. For Tax-Exempt Funds: If a Tax-Exempt Fund were to fail to qualify for treatment as a regulated investment company, the Fund could not pass through the tax-exempt character of income it receives to shareholders, and any dividends paid by the Fund in respect of its net tax-exempt income in general, would be taxable to you as ordinary income.

■

Otherwise taxable distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares. Dividends paid in January are deemed paid on December 31 of the prior year if the dividend was declared and payable to shareholders of record in October, November, or December of such prior year.

■

Distributions of the Fund's ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund's net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares. Certain events may require the Fund to sell significant amounts of appreciated securities and make large dividends relative to the Fund’s NAV. Such events may include portfolio rebalancing or fund mergers. The Fund generally provides estimates of expected capital gain dividends (if any) prior to the distribution on columbiathreadneedleus.com/etfs. The Fund expects to distribute net capital gains (if any) resulting from the Fund’s portfolio re-balancing, maturities, and other taxable dispositions of securities.

■

From time to time, a distribution from the Fund could constitute a return of capital. A return of capital is a return of an amount of your original investment and is not a distribution of income or capital gain from the Fund. Therefore, a return of capital is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

■

If you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at the lower net long-term capital gain rates instead of the higher ordinary income rates. Qualified dividend income is income attributable to the Fund's dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The Fund does not expect a significant portion of Fund distributions to be eligible for treatment as qualified dividend income.

■	Certain high-income individuals (as well as estates and trusts) are subject to a 3.8% tax on net investment income. For individuals, the 3.8% tax applies to the lesser of (1) the amount (if any) by which the taxpayer's modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer's “net investment income.”
	Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net gains recognized on the sale, redemption or exchange of shares of the Fund. For Tax-Exempt Funds: Exempt-interest dividends are not included in net investment income for this purpose, and are therefore not subject to the tax on net investment income.

■

Certain derivative instruments when held in the Fund's portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Distributions and Taxes (continued)

into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders. For Tax-Exempt Funds: Derivative instruments held by a Fund may also generate taxable income to the Fund.

■

Generally, a Fund realizes a capital gain or loss on an option when the option expires, or when it is exercised, sold or otherwise terminated. However, if an option is a “section 1256 contract,” which includes most traded options on a broad-based index, and the Fund holds such option at the end of its taxable year, the Fund is deemed to sell such option at fair market value at such time and recognize any gain or loss thereon, which is generally deemed to be 60% long-term and 40% short-term capital gain or loss, as described further in the SAI.

■

For Tax-Exempt Funds: The Fund expects that distributions will consist primarily of exempt-interest dividends. Distributions of the Fund's net interest income from tax-exempt securities generally are not subject to U.S. federal income tax, but may be subject to state and local income and other taxes, as well as U.S. federal and state alternative minimum tax. Similarly, distributions of interest income that is exempt from state and local income taxes of a particular state may be subject to other taxes, including income taxes of other states, and U.S. federal and state alternative minimum tax. Certain income generated by tax-exempt securities, including capital gains on sales and market discount, is taxable. The Fund may invest a portion of its assets in securities that generate income that is not exempt from U.S. federal or state income tax. Distributions by the Fund of this income generally are taxable to you as ordinary income or long-term capital gain. Distributions of capital gains realized by the Fund, including those generated from the sale or exchange of tax-exempt securities, generally also are taxable to you. Distributions of the Fund's net short-term capital gain, if any, generally are taxable to you as ordinary income.

■

A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares, including those paid in securities or other instruments, usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and your adjusted tax basis in the shares, which is generally the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

■

Your broker will be responsible for furnishing tax reporting information for Fund shares held in a nonqualified account, shareholder reports, and other communications from the Fund. For sales or exchanges of Fund shares acquired in a nonqualified account after 2011, your broker is required to report basis and holding period information to you and the IRS. Your broker may offer a choice of basis calculation methods. Contact your broker to determine which basis methods are available for your account.

■

The Fund or, in the case of sales of Fund shares in the secondary market, your broker, will generally be required by federal law to withhold tax on any distributions and proceeds paid to you if you have not provided a correct taxpayer identification number (TIN) or have not certified to the Fund or its agent, or your broker, as the case may be, that withholding does not apply.

■

For Authorized Participants Purchasing and Redeeming in Creation Units: An Authorized Participant that exchanges equity securities for one or more Creation Units will generally recognize a gain or a loss on the exchange. The gain or loss will be equal to the difference between (i) the market value of the Creation Unit(s) at the time and, (ii) the exchanger’s aggregate basis in the securities surrendered plus (or minus) the Cash Component paid (or received). A person who redeems one or more Creation Units for equity securities will generally recognize a gain or loss equal to the difference between (i) the exchanger’s basis in the Creation Unit(s) and, (ii) the aggregate market value of the securities received plus (or minus) the Cash Component received (or paid). The IRS, however, may assert that a loss realized upon an exchange of securities for Creation Unit(s) cannot be deducted currently under the rules governing “wash sales,” or on the basis that there has been no significant change in economic position. Persons exchanging securities should consult their own tax advisors with respect to whether wash sale rules apply and when a loss might be deductible. Any capital gain or loss realized upon a redemption of one or more Creation Units is generally treated as long-term capital gain or loss if the Creation

36	Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

Financial Highlights

The financial highlights table is intended to help you understand the Fund’s financial performance for the past five fiscal years or, if shorter, the Fund’s period of operations. Certain information reflects financial results for a single Fund share. The total return in the table represents the rate that an investor would have earned (or lost) on an investment in the Fund assuming all dividends and distributions had been reinvested. This information has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, whose report, along with the Fund’s financial statements, is included in the Fund’s annual report, which is available upon request.

	Year Ended October 31,
	2022	2021	2020	2019	2018^(a)
Per share data
Net asset value, beginning of year	$22.30	$21.83	$21.56	$20.02	$20.00
Income (loss) from investment operations:
Net investment income	0.34	0.37	0.51	0.56	0.03
Net realized and unrealized gain (loss)	(3.03)	0.52	0.30	1.51	(0.01)
Total from investment operations	(2.69)	0.89	0.81	2.07	0.02
Less distributions to shareholders:
Net investment income	(0.32)	(0.38)	(0.51)	(0.53)	–
Net realized gains	(0.02)	(0.04)	(0.03)	–	–
Total distribution to shareholders	(0.34)	(0.42)	(0.54)	(0.53)	–
Net asset value, end of year	$19.27	$22.30	$21.83	$21.56	$20.02
Total Return at NAV	(12.17)%	4.11%	3.82%	10.42%	0.10%
Total Return at Market	(12.40)%	3.85%	4.18%	10.24%	0.45%
Ratios to average net assets:
Total gross expenses^(b)	0.23%^(c)	0.23%^(c)	0.23%	0.26%	0.28%^(d)
Total net expenses^(b)(e)	0.23%^(c)	0.23%^(c)	0.23%	0.26%	0.28%^(d)
Net investment income	1.63%	1.65%	2.37%	2.67%	2.34%^(d)
Supplemental data
Net assets, end of year (in thousands)	$223,585	$141,619	$56,769	$26,946	$16,014
Portfolio turnover	14%	6%	11%	20%	48%

(a)	The Fund commenced operations on October 10, 2018. Per share data and total return reflect activity from that date.
(b)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests. Such indirect expenses are not included in the Fund’s reported expense ratios.

(c)	The ratio includes less than 0.01% attributed to overdraft expense, which is outside the Unitary Fee (as defined in Note 3).

(d)	Annualized
(e)	Total net expenses include the impact of certain fee waivers/expense reimbursements made by the Investment Manager and certain of its affiliates, if applicable.

Prospectus 2023

Table of Contents

Columbia Multi-Sector Municipal Income ETF

290 Congress Street
Boston, MA 02210

Additional Information About the Fund

Additional information about the Fund’s investments is available in the Fund’s annual and semiannual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year. The SAI also provides additional information about the Fund and its policies. The SAI, which has been filed with the SEC, is legally part of this prospectus (incorporated by reference). To obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries, please contact the Fund as follows:

By Mail: Columbia Funds
290 Congress Street
Boston, MA 02210

By Telephone: 800.426.3750

Online: columbiathreadneedleus.com/etfs

Information on the Fund’s net asset value, market price, premiums and discounts, and bid-ask spreads can be found on the Fund's website at columbiathreadneedleus.com/etfs.

Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a duplication fee, by electronic request at the following e-mail address: [email protected].

The investment company registration number of Columbia ETF Trust I, of which the Fund is a series, is 811-22736.

Columbia Threadneedle Investments is the global brand name of the Columbia and Threadneedle group of companies.

PRO303_10_N01_(03/23)

Web site information
Fund	Internet address
Columbia Multi-Sector Municipal Income ETF	https://www.columbiathreadneedleus.com/investment-products/details/?cusip=19761L607