Calamos Calamos ETF Trust Convertible Equity Alternative ETF Prospectus [Funds] 05-15-2023 ED [AU

Calamos Convertible Equity Alternative ETF
(NYSE Arca—CVRT)

Prospectus October 2, 2023

Calamos Convertible Equity Alternative ETF (the "Fund") is a series of the Calamos ETF Trust (the "Trust") and an exchange-traded fund ("ETF"). The Fund lists and principally trades its shares on the NYSE Arca, Inc. ("NYSE Arca" or the "Exchange").

The U.S. Securities and Exchange Commission ("SEC") has not approved or disapproved these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.


 

Table of Contents

Calamos Convertible Equity
Alternative ETF
   

1

   
Other Important Information
Regarding Fund Shares
   

7

   
Additional Information About
Investment Strategies and Related
Risks
   

8

   

Fund Facts

   

17

   

Who Manages the Fund?

   

17

   

How to Buy and Sell Shares

   

18

   
Dividends, Other Distributions and
Taxes
   

20

   

Net Asset Value

   

23

   

Fund Service Providers

   

24

   

Premium/Discount Information

   

24

   
Investments by Other Investment
Companies
   

24

   

Financial Highlights

   

26

   

Other Information

   

27

   

Calamos Convertible Equity Alternative ETF

Investment Objective

The Calamos Convertible Equity Alternative ETF's investment objective is total return through capital appreciation and current income.

Fees and Expenses of the Fund

The following table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund ("Fund Shares"). Investors may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments):

Management Fees

   

0.69

%

 

Distribution and/or Service Fees (12b-1)

   

0.00

%

 

Other Expenses1

   

0.00

%

 

Total Annual Fund Operating Expenses

   

0.69

%

 

1  "Other Expenses" is an estimate based on the expenses the Fund expects to incur for the current fiscal year.

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, and then sell all of your Fund Shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs, whether you sell or hold your Fund Shares, would be:

Year 1  

Year 3

 
$

70

   

$

221

   

Portfolio Turnover

The Fund pays 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. Because the Fund has not yet commenced operations, portfolio turnover information is unavailable at this time.

Principal Investment Strategies

The Fund is an actively managed exchange-traded fund ("ETF") that invests in the segment of the U.S. convertibles marketplace that has a higher level of equity sensitivity. The Fund seeks to achieve its objective by investing at least 80% of its net assets (plus borrowings for investment purposes, if any) in a portfolio of convertible securities (including synthetic convertible instruments). The Fund's investment adviser is Calamos Advisors LLC ("Calamos Advisors" or the "Adviser").

The Adviser utilizes a quantitative and qualitative screening process that consists of a proprietary convertible model and fundamental inputs to identify securities that meet the criteria for inclusion in the portfolio and intends to rebalance the portfolio regularly to ensure that the desired exposures are maintained. The Adviser will also make active adjustments to the portfolio based on fundamental analyses (such as an issuer's financial soundness, ability to make interest and dividend payments, earnings and cash flow forecast and quality of management), as well as certain portfolio-level characteristics, such as size of an issue (e.g., value of bonds outstanding), liquidity, trade execution, and exposure to macro-level investment themes.

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1


Calamos Convertible Equity Alternative ETF

Convertible debt securities are exchangeable for equity securities of the issuer at a predetermined price, and typically offer greater appreciation potential than non-convertible debt securities. The convertible securities in which the Fund may invest consist of U.S. bonds, structured notes, debentures and preferred stocks, which may be converted or exchanged at a stated or determinable exchange ratio into underlying shares. Structured notes are fixed-income debentures linked to equity. Convertible structured notes have the attributes of a convertible security, however, the investment bank that issued the convertible note assumes the credit risk associated with the investment, rather than the issuer of the underlying common stock into which the note is convertible. The bonds, structured notes and debentures may be rated investment grade or below investment grade or may not be rated, may be issued by corporations, governments or public international bodies and may be denominated in a variety of currencies and issued with either fixed or floating rates. Bonds rated below investment grade are commonly known as "junk bonds." Convertible securities may offer higher income than the shares into which they are convertible. The Fund may be required to permit the issuer of a convertible security to redeem the security, convert it into the underlying shares or sell it to a third party. Convertible securities include debt obligations and preferred stock of the company issuing the security, which may be exchanged for a predetermined price (the conversion price), into the issuer's common stock.

The Fund may invest up to 20% of its net assets in foreign securities. Foreign securities are securities issued by issuers that are organized under the laws of a foreign country or that have a substantial portion of their operations or assets in a foreign country or countries, or that derive a substantial portion of their revenue or profits from businesses, investments or sales outside of the United States. The Fund may also invest in foreign securities that are represented in the United States securities markets by American Depositary Receipts ("ADRs") or similar depository arrangements. The Fund's foreign securities can be denominated in U.S. dollars or in foreign currencies. Debt securities issued by a foreign government may not be supported by the "full faith and credit" of that government.

Certain convertible debt securities include a "put option" which entitles the Fund to sell the security to the issuer before maturity at a stated price, which may represent a premium over the stated principal amount of the debt security. Conversely many convertible securities are issued with a "call" feature that allows the security's issuers to choose when to redeem the security.

A synthetic convertible instrument is designed to simulate the economic characteristics of a convertible security through the combined features of a debt instrument and a security providing an option on an equity security. The Fund may establish a synthetic convertible instrument by combining a fixed-income security (which may be either convertible or non-convertible) with the right to acquire an equity security. The fixed-income and equity option components may have different issuers, and either component may change at any time.

The Fund is classified as "non-diversified" under the Investment Company Act of 1940 (the "1940 Act").

Principal Risks

An investment in the Fund is subject to risks, and you could lose money on your investment in the Fund. There can be no assurance that the Fund will achieve its investment objective. You should not consider investing in the Fund if your investment objective differs from the Fund's investment objective or if you are not willing to accept the principal risks associated with an investment in the Fund. The risks associated with an investment in the Fund can increase during times of significant market volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears. The principal risks of investing in the Fund include:

•  Authorized Participant Concentration Risk — Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the

CALAMOS CONVERTIBLE EQUITY ALTERNATIVE ETF
2


Calamos Convertible Equity Alternative ETF

Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

•  Convertible Securities Risk — The value of a convertible security is influenced by changes in interest rates, with investment value declining as interest rates increase and increasing as interest rates decline. The credit standing of the issuer and other factors also may have an effect on the convertible security's investment value. Convertible securities generally offer lower interest or dividend yields than non-convertible fixed-income securities of similar credit quality because of the potential for capital appreciation. In addition, the value of a convertible security is influenced by the interest rate environment, company credit risk, and by the value of the underlying common stock. As the market price of the underlying common stock declines below the conversion price, the price of the convertible security tends to be increasingly influenced by the credit quality, maturity and yield of the convertible security. Holders of convertible securities have a claim on the issuer's assets prior to the common stockholders, but may be subordinated to holders of similar but non-convertible securities of the same issuer.

•  Costs of Buying and Selling Fund Shares — Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

•  Debt Securities Risk — Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

•  Interest Rate Risk — The value of debt securities generally decreases in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter term debt securities. Recent fixed-income market events, including increases in volatility and interest rates, may expose the Fund to heightened interest rate risk and volatility.

•  Credit Risk — A debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, the Fund's performance could be negatively affected.

•  Default Risk — A company that issues a debt security may be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

•  Equity Securities Risk — The securities markets are volatile, and the market prices of the Fund's securities may decline generally. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions. If the market prices of the securities owned by the Fund fall, the value of your investment in the Fund will decline.

•  Foreign Securities Risk — Risks associated with investing in foreign securities include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, the possibility of substantial price volatility as a result of political and economic instability in the foreign country, less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity than in U.S. markets.

•  High Yield Risk — High yield securities and unrated securities of similar credit quality (commonly known as "junk bonds") are subject to greater levels of credit and liquidity risks. High yield securities are considered primarily speculative with respect to the issuer's continuing ability to make principal and interest payments.

•  Large-Capitalization Investing Risk — Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

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3


Calamos Convertible Equity Alternative ETF

•  Market Maker Risk — If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

•  Market Risk — The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

•  National Closed Market Trading Risk — To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

•  New Fund Risk — The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

•  Non-Diversification Risk — The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended.

•  Options Risk — The Fund's ability to close out its position as a purchaser or seller of an over-the-counter or exchange-listed put or call option is dependent, in part, upon the liquidity of the option market. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on the ability of the Fund's investment adviser to predict pertinent market movements, which cannot be assured.

•  Portfolio Selection Risk — The value of your investment may decrease if Calamos Advisors' judgment about the attractiveness, value or market trends affecting a particular security, issuer, industry or sector or about market movements is incorrect.

•  Portfolio Turnover Risk — The portfolio managers may actively and frequently trade securities or other instruments in the Fund's portfolio to carry out its investment strategies. A high portfolio turnover rate increases transaction costs, which may increase the Fund's expenses. Frequent and active trading may also cause adverse tax consequences for investors in the Fund due to an increase in short-term capital gains.

•  Premium-Discount Risk — Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

•  Rule 144A Securities Risk — The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its board of trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

CALAMOS CONVERTIBLE EQUITY ALTERNATIVE ETF
4


Calamos Convertible Equity Alternative ETF

•  Secondary Market Trading Risk — Investors buying or selling Fund Shares in the secondary market 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 Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

•  Sector Risk — To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market, and it is possible that the Fund may underperform the broader market or experience greater volatility.

•  Securities Lending Risk — The Fund may lend its portfolio securities to broker-dealers and banks in order to generate additional income for the Fund. Any such loan must be continuously secured by collateral in cash or cash equivalents maintained on a current basis in an amount at least equal to the market value of the securities loaned by the Fund. In the event of bankruptcy or other default of a borrower of portfolio securities, the Fund could experience both delays in liquidating the loan collateral or recovering the loaned securities and losses, including (a) possible decline in the value of the collateral or in the value of the securities loaned during the period while the Fund seeks to enforce its rights thereto, (b) possible subnormal levels of income and lack of access to income during this period, and (c) expenses of enforcing its rights. In an effort to reduce these risks, the Fund's securities lending agent monitors, and reports to Calamos Advisors on, the creditworthiness of the firms to which the Fund lends securities. The Fund may also experience losses as a result of a diminution in value of its cash collateral investments.

•  Small and Mid-Sized Company Risk — Small and mid-sized company stocks have historically been subject to greater investment risk than large company stocks. The risks generally associated with these companies include more limited product lines, markets and financial resources, lack of management depth or experience, dependency on key personnel, and vulnerability to adverse market and economic developments. Accordingly, the prices of mid-sized company stocks tend to be more volatile than prices of large company stocks. Further, the prices of small company stocks are often adversely affected by limited trading volumes and the lack of publicly available information.

•  Synthetic Convertible Instruments Risk — The value of a synthetic convertible instrument will respond differently to market fluctuations than a convertible security because a synthetic convertible instrument is composed of two or more separate securities, each with its own market value. In addition, if the value of the underlying common stock or the level of the index involved in the convertible component falls below the exercise price of the warrant or option, the warrant or option may lose all value.

•  Trading Issues Risk — Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

Fund Performance

The Fund had not commenced operations as of the date of this prospectus. Once available, the Fund's performance information, and information that gives some indication of the risks of an investment in the Fund by comparing the Fund's performance with a broad measure of market performance, will be available on the Fund's website at: www. calamos.com. Past performance (before and after taxes) is not an indication of future performance.

PROSPECTUS | October 2, 2023
5


Calamos Convertible Equity Alternative ETF

Investment Adviser

Calamos Advisors LLC ("Calamos Advisors" or the "Adviser")

Portfolio Managers

PORTFOLIO MANAGER/
FUND TITLE (IF APPLICABLE)
  PORTFOLIO MANAGER
EXPERIENCE IN THE FUND
  PRIMARY TITLE
WITH ADVISER
 

John Hillenbrand

 

Since October 2023

 

SVP, Sr. Co-Portfolio Manager

 

Joe Wysocki

 

Since October 2023

 

SVP, Sr. Co-Portfolio Manager

 

Jon Vacko

 

Since October 2023

 

SVP, Sr. Co-Portfolio Manager

 

CALAMOS CONVERTIBLE EQUITY ALTERNATIVE ETF
6


Other Important Information Regarding Fund Shares

Portfolio Holdings. The Fund's portfolio holdings are disclosed on its website daily after the close of trading on the Exchange and prior to the opening of trading on the Exchange the following day. A description of the Fund's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's Statement of Additional Information ("SAI").

Premium/Discount Information. Information about the premiums and discounts at which the Fund's Shares have traded will be available at www.calamos.com.

Purchase and Sale of Fund Shares

The Fund will issue (or redeem) Fund Shares to certain institutional investors (typically market makers or other broker-dealers) only in large blocks of Fund Shares known as "Creation Units." Creation Unit transactions are conducted in exchange for the deposit or delivery of a designated portfolio of in-kind securities and/or cash.

Individual Fund Shares may only be purchased and sold on the Exchange, other national securities exchanges, electronic crossing networks and other alternative trading systems through your broker-dealer at market prices. Because Fund Shares trade at market prices rather than at net asset value ("NAV"), Fund Shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling Fund Shares in the secondary market, you may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase Fund Shares (bid) and the lowest price a seller is willing to accept for Fund Shares (ask) (the "bid-ask spread"). Recent information regarding the Fund's NAV, market price, premiums and discounts, and bid-ask spreads is available at https://www.calamos.com/.

Tax Information

Net investment income and capital gains distributions you receive from the Fund generally are subject to federal income taxes and may also be subject to state and local taxes. The Fund intends to distribute net investment income, if any, monthly, and capital gains, if any, at least annually.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund 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 salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

PROSPECTUS | October 2, 2023
7


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Additional Information About Investment Strategies
and Related Risks

The Fund's investment objective, the 80% investment strategy and each of the policies described herein are non-fundamental policies that may be changed by the Board of Trustees of the Trust (the "Board") without shareholder approval. The Fund may liquidate and terminate at any time without shareholder approval.

What are the investment objective and principal strategies for the Fund?

The Fund's investment objective is total return through capital appreciation and current income.

The Fund is an actively managed exchange-traded fund ("ETF") that invests in the segment of the U.S. convertibles marketplace that has a higher level of equity sensitivity. The Fund seeks to achieve its objective by investing at least 80% of its net assets (plus borrowings for investment purposes, if any) in a portfolio of convertible securities (including synthetic convertible instruments). The Fund's investment adviser is Calamos Advisors LLC ("Calamos Advisors" or the "Adviser").

The Adviser utilizes a quantitative and qualitative screening process that consists of a proprietary convertible model and fundamental inputs to identify securities that meet the criteria for inclusion in the portfolio and intends to rebalance the portfolio regularly to ensure that the desired exposures are maintained. The Adviser will also make active adjustments to the portfolio based on fundamental analyses (such as an issuer's financial soundness, ability to make interest and dividend payments, earnings and cash flow forecast and quality of management), as well as certain portfolio-level characteristics, such as size of an issue (e.g., value of bonds outstanding), liquidity, trade execution, and exposure to macro-level investment themes.

Convertible debt securities are exchangeable for equity securities of the issuer at a predetermined price, and typically offer greater appreciation potential than non-convertible debt securities. The convertible securities in which the Fund may invest consist of U.S. bonds, structured notes, debentures and preferred stocks, which may be converted or exchanged at a stated or determinable exchange ratio into underlying shares. Structured notes are fixed-income debentures linked to equity. Convertible structured notes have the attributes of a convertible security, however, the investment bank that issued the convertible note assumes the credit risk associated with the investment, rather than the issuer of the underlying common stock into which the note is convertible. The bonds, structured notes and debentures may be rated investment grade or below investment grade or may not be rated, may be issued by corporations, governments or public international bodies and may be denominated in a variety of currencies and issued with either fixed or floating rates. Bonds rated below investment grade are commonly known as "junk bonds." Convertible securities may offer higher income than the shares into which they are convertible. The Fund may be required to permit the issuer of a convertible security to redeem the security, convert it into the underlying shares or sell it to a third party. Convertible securities include debt obligations and preferred stock of the company issuing the security, which may be exchanged for a predetermined price (the conversion price), into the issuer's common stock.

The Fund may invest up to 20% of its net assets in foreign securities. Foreign securities are securities issued by issuers that are organized under the laws of a foreign country or that have a substantial portion of their operations or assets in a foreign country or countries, or that derive a substantial portion of their revenue or profits from businesses, investments or sales outside of the United States. The Fund may also invest in foreign securities that are represented in the United States securities markets by American Depositary Receipts ("ADRs") or similar depository arrangements. The Fund's foreign securities can be denominated in U.S. dollars or in foreign currencies. Debt securities issued by a foreign government may not be supported by the "full faith and credit" of that government.

Certain convertible debt securities include a "put option" which entitles the Fund to sell the security to the issuer before maturity at a stated price, which may represent a premium over the stated principal amount of the debt security. Conversely many convertible securities are issued with a "call" feature that allows the security's issuers to choose when to redeem the security.

A synthetic convertible instrument is designed to simulate the economic characteristics of a convertible security through the combined features of a debt instrument and a security providing an option on an equity security. The Fund may establish a synthetic convertible instrument by combining a fixed-income security (which may be either convertible or non-convertible)

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with the right to acquire an equity security. The fixed-income and equity option components may have different issuers, and either component may change at any time.

The Fund is classified as "non-diversified" under the Investment Company Act of 1940 (the "1940 Act").

Changes in 80% policy

The Fund has adopted a non-fundamental operating policy that requires it, under normal circumstances, to invest at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in convertible securities. Although this requirement may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders at least 60 days prior to any change in its 80% policy.

Fund Investments

Principal Investments

Convertible Securities (including Synthetic Convertible Instruments)

The Fund invests in convertible securities (including synthetic convertible instruments). Convertible securities include, but are not limited to, any corporate debt security, debentures, notes or preferred stock that may be converted into equity securities of companies around the world, including in emerging markets. A synthetic convertible instrument is designed to simulate the economic characteristics of a convertible security through the combined features of a debt instrument and a security providing an option on an equity security. The Fund may establish a synthetic convertible instrument by combining a fixed-income security (which may be either convertible or non-convertible) with the right to acquire an equity security. The fixed-income and equity option components may have different issuers, and either component may change at any time.

In addition, the value of a convertible security is influenced by the interest rate environment, company credit risk, and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value increases as prevailing interest rate levels decline. However, a convertible security's market value will also be influenced by its "conversion value," which is the market value of the underlying common stock that would be obtained if the convertible security were converted. A convertible security's conversion value tends to increase as the price of the underlying common stock increases, and decrease as the price of the underlying common stock decreases.

As the market price of the underlying common stock declines below the conversion price, the price of the convertible security tends to be increasingly influenced by the credit quality, maturity and yield of the convertible security. Thus, it may not decline in price to the same extent as the underlying common stock.

If the market price of the underlying common stock increases to a point where the conversion value approximates or exceeds the investment value, the price of the convertible security tends to be influenced more by the market price of the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. Consequently, the issuer's convertible securities entail less risk than its common stock.

Equity Securities

The Fund invests in equity securities, including common stock. Common stock represents an equity ownership interest in issuers. Holders of common stock are entitled to the income and increase in the value of the assets and business of the issuers after all debt obligations and obligations to preferred stockholders are satisfied.

Non-Principal Investments

Cash Equivalents and Short-Term Investments

The Fund may invest in securities with maturities of less than one year or cash equivalents, or it may hold cash. The percentage of the Fund invested in such holdings varies and depends on several factors, including market conditions. For temporary defensive purposes and during periods of high cash inflows or outflows, the Fund may invest part or all of its assets in these securities or it may hold cash. During such periods, the Fund may not be able to achieve its investment objective. The Fund may adopt a defensive strategy when the portfolio managers believe securities in which such Fund normally invests have elevated

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risks due to political or economic factors and in other extraordinary circumstances. For more information on eligible short-term investments, see the SAI.

Illiquid Investments

The Fund may invest up to 15% of its net assets in securities and other instruments that are, at the time of investment, illiquid (determined using the Securities and Exchange Commission's standard applicable to investment companies, 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). For this purpose, illiquid investments may include, but are not limited to, certain restricted securities (securities the disposition of which is restricted under the federal securities laws), certain securities that may only be resold pursuant to Rule 144A under the Securities Act, and certain repurchase agreements, among others.

Risks of Investing in the Fund

This prospectus describes the risks you may face as an investor in the Fund. It is important to keep in mind that generally, investments with a higher potential reward also have a higher risk of losing money. The reverse is also commonly true: the lower the risk, the lower the potential reward. However, as you consider an investment in the Fund, you should also take into account your tolerance for the daily fluctuations of the financial markets and whether you can afford to leave your money in this investment for a long period of time to ride out down periods.

As with any security, there are market and investment risks associated with your investment in the Fund. The value of your investment will fluctuate over time, and it is possible to lose money. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears.

In response to market, economic, political, or other conditions, the Fund may temporarily invest for defensive purposes that are inconsistent with the Fund's principal investment strategies. If the Fund does so, different factors could affect the Fund's performance, and the Fund may not achieve its investment objective.

Principal Risks

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

Convertible Securities Risk. The value of a convertible security is influenced by both the yield of non-convertible securities of comparable issuers and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value increases as prevailing interest rate levels decline. However, a convertible security's market value will also be influenced by its "conversion value," which is the market value of the underlying common stock that would be obtained if the convertible security were converted. A convertible security's conversion value tends to increase as the price of the underlying common stock increases, and decrease as the price of the underlying common stock decreases.

As the market price of the underlying common stock declines such that the conversion value is substantially below the investment value of the convertible security, the price of the convertible security tends to be influenced more by the yield of the convertible security. Thus, it may not decline in price to the same extent as the underlying common stock.

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If the market price of the underlying common stock increases to a point where the conversion value approximates or exceeds the investment value, the price of the convertible security tends to be influenced more by the market price of the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. Consequently, the issuer's convertible securities entail less risk than its common stock.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

Debt Securities Risk. Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

Interest Rate Risk. Interest rate risk is the risk that the Fund's investments in debt securities will decrease in value as a result of an increase in interest rates. Generally, there is an inverse relationship between the value of a debt security and interest rates. Therefore, the value of debt securities generally decrease in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter-term debt securities. Recent fixed-income market events, including changes in interest rates by the Federal Reserve Board, may subject the Fund to heightened interest rate risk as a result of a rise in interest rates. In addition, the Fund is subject to the risk that interest rates may exhibit increased volatility, which could cause the Fund's net asset value to fluctuate more. A decrease in fixed-income market maker capacity may act to decrease liquidity in the fixed-income markets and act to further increase volatility, affecting the Fund's return. Many financial instruments use or may use a floating rate which historically has been based on the London Interbank Offered Rate ("LIBOR"), which was the offered rate for short-term Eurodollar deposits between major international banks. In connection with the global transition away from LIBOR led by regulators and market participants, LIBOR was last published on a representative basis at the end of June 2023. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR in most major currencies and the transition to new reference rates continues. Markets in these new rates are developing, but questions around liquidity and how to appropriately adjust these rates to mitigate any economic value transfer at the time of transition remain a concern. Neither the effect of the transition process nor its ultimate success can yet be known. The transition away from LIBOR and the use of replacement rates may adversely affect transactions that used LIBOR as a reference rate, financial institutions, funds and other market participants that engaged in such transactions, and the financial markets generally.

Credit Risk. Credit risk is the risk that a debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, such Fund's performance could be negatively affected.

Default Risk. Default risk refers to the risk that a company that issues a debt security will be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

Equity Securities Risk. Equity investments are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions.

Foreign Securities Risk. There are special risks associated with investing in foreign securities that are not typically associated with investing in U.S. companies. These risks include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, and the possibility of substantial price volatility as a result of political and economic instability in the foreign country. Other risks of investing in foreign securities include: less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity in foreign markets than in U.S. markets.

High Yield Fixed-Income Securities (Junk Bonds) Risk. Investment in junk bonds entails a greater risk than an investment in higher-rated securities. Although junk bonds typically pay higher interest rates than investment-grade bonds, there is a greater likelihood that the company issuing the junk bond will default on interest and principal payments. In the event of an issuer's

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bankruptcy, claims of other creditors may have priority over the claims of junk bond holders, leaving few or no assets to repay them. Junk bonds are also more sensitive to adverse economic changes or individual corporate developments than higher quality bonds. During a period of adverse economic changes, including a period of rising interest rates, companies issuing junk bonds may be unable to make principal and interest payments.

Large-Capitalization Investing Risk. Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Market Maker Risk. If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

Market Risk. The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

National Closed Market Trading Risk. To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

New Fund Risk. The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

Non-Diversification Risk. The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.

Options Risk. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on Calamos Advisors' ability to predict pertinent market movements, which cannot be assured.

The Fund's ability to close out its position as a purchaser or seller of an Options Clearing Corporation or exchange-listed put or call option is dependent, in part, upon the liquidity of the options market. If the Fund were unable to close out an option that it had purchased on a security, it would have to exercise the option to realize any profit or the option would expire and become worthless. If the Fund were unable to close out a covered call option that it had written on a security, it would not be able to sell the underlying security until the option expired. As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call. The hours of trading for listed options may not coincide with the hours during which the underlying financial instruments are traded. To the extent that the option markets close before the

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markets for the underlying financial instruments, significant price and rate movements can take place in the underlying markets that cannot be reflected in the option markets until the next trading day.

Unless the parties provide for it, there is no central clearing or guaranty function in an over-the-counter option. As a result, if the counterparty fails to make or take delivery of the security or other instrument underlying an over-the-counter option it has entered into with the Fund or fails to make a cash settlement payment due in accordance with the terms of that option, the Fund will lose any premium it paid for the option as well as any anticipated benefit of the transaction. Accordingly, Calamos Advisors must assess the creditworthiness of each such counterparty or any guarantor or credit enhancement of the counterparty's credit to determine the likelihood that the terms of the over-the-counter option will be satisfied.

The Fund may also purchase or write over-the-counter put or call options, which involves risks different from, and possibly greater than, the risks associated with exchange-listed put or call options. In some instances, over-the-counter put or call options may expose the Fund to the risk that a counterparty may be unable or unwilling to perform according to a contract, and that any deterioration in a counterparty's creditworthiness could adversely affect the instrument. In addition, the Fund may be exposed to a risk that losses may exceed the amount originally invested.

Portfolio Selection Risk. The value of your investment may decrease if the judgment of Calamos Advisors about the attractiveness, value or market trends affecting a particular security, issuer, industry, or sector or about market movements is incorrect.

Portfolio Turnover Risk. Engaging in active and frequent trading of securities may result in a higher than average level of capital gains and greater transaction costs to the Fund, including brokerage commissions or dealer mark-ups and other transaction costs on the sale and reinvestments of securities. Such sales may also result in the realization of capital gains, including short-term capital gains (which are taxed at ordinary income tax rates for federal income tax purposes, rather than at lower capital gains rates) and may adversely impact the Fund's performance. It is possible that the Fund engaging in active and frequent trading may be required to make significant distributions derived from taxable gains, regardless of the Fund's net longer term performance. The trading costs and tax effects associated with portfolio turnover will adversely affect the Fund's performance and lower the Fund's effective return for investors.

Premium-Discount Risk. The Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

Rule 144A Securities Risk. The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its board of trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Secondary Market Trading Risk. Investors buying or selling Fund Shares in the secondary market 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 Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

Sector Risk. To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market and it is possible that the Fund may underperform the broader market, or experience greater volatility.

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Securities Lending Risk. The Fund may lend its portfolio securities to broker-dealers and banks in order to generate additional income for the Fund. Any such loan must be continuously secured by collateral in cash or cash equivalents maintained on a current basis in an amount at least equal to the market value of the securities loaned by the Fund. In the event of bankruptcy or other default of a borrower of portfolio securities, the Fund could experience both delays in liquidating the loan collateral or recovering the loaned securities and losses, including (a)possible decline in the value of the collateral or in the value of the securities loaned during the period while the Fund seeks to enforce its rights thereto, (b)possible subnormal levels of income and lack of access to income during this period, and (c)expenses of enforcing its rights. In an effort to reduce these risks, the Fund's securities lending agent monitors, and reports to Calamos Advisors on, the creditworthiness of the firms to which the Fund lends securities. The Fund may also experience losses as a result of a diminution in value of its cash collateral investments.

Small and Mid-Sized Company Risk. Small and mid-sized company stocks have historically been subject to greater investment risk than large company stocks. The risks generally associated with these companies include more limited product lines, markets and financial resources, lack of management depth or experience, dependency on key personnel, and vulnerability to adverse market and economic developments. Accordingly, the prices of mid-sized company stocks tend to be more volatile than prices of large company stocks. Further, the prices of small company stocks are often adversely affected by limited trading volumes and the lack of publicly available information.

Synthetic Convertible Instruments Risk. The value of a synthetic convertible instrument will respond differently to market fluctuations than a convertible security because a synthetic convertible instrument is composed of two or more separate securities, each with its own market value. In addition, if the value of the underlying common stock or the level of the index involved in the convertible component falls below the exercise price of the warrant or option, the warrant or option may lose all value.

Trading Issues Risk. Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

The following are non-principal risks that generally apply to the Fund:

Cybersecurity Risk. Investment companies, such as the Fund, and their service providers are exposed to operational and information security risks resulting from cyberattacks, which may result in financial losses to the Fund and its shareholders. Cyber- attacks include, among other behaviors, stealing or corrupting data maintained online or digitally, denial of service attacks on websites, "ransomware" that renders systems inoperable until ransom is paid, the unauthorized release of confidential information, or various other forms of cybersecurity breaches. Cyber-attacks affecting the Fund, Calamos Advisors, custodian, transfer agent, distributor, administrator, intermediaries, trading counterparties, and other third-party service providers may adversely impact the Fund or the companies in which the Fund invests, causing the Fund's investments to lose value or to prevent a shareholder redemption or purchase from clearing in a timely manner.

Inflation Risk. The risk that the value of assets or income from the Fund's investments will be worth less in the future as inflation decreases the value of payments at future dates is considered inflation risk. As inflation increases, the value of the Fund's portfolio could decline. Inflation rates may change frequently and drastically as a result of various factors and the Fund's investments may not keep pace with inflation, which may result in losses to the Fund's investors or adversely affect the value of shareholders' investments in the Fund. Inflation has recently increased, and it cannot be predicted whether it may decline.

Investment Management Risk. Whether the Fund achieves its investment objective(s) is significantly impacted by whether Calamos Advisors is able to choose suitable investments for the Fund.

Market Disruption Risk. Certain events have a disruptive effect on securities markets, including but not limited to, terrorist attacks, war and other geopolitical events or catastrophes. Calamos Advisors cannot predict the effect of similar events in the

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future on the U.S. or foreign economies. Certain securities such as high yield and equity securities tend to be impacted more by these events than other types of securities in terms of price and volatility.

Operational Risk. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund's ability to meet its investment objective. Although the Fund and the Adviser seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.

Recent Market Events. Since the 2008 financial crises, financial markets throughout the world have experienced periods of increased volatility, depressed valuations, decreased liquidity and heightened uncertainty and turmoil. This turmoil resulted in unusual and extreme volatility in the equity and debt markets, in the prices of individual securities and in the world economy. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events, geopolitical events (including wars, terror attacks, and public health emergencies), measures to address budget deficits, downgrading of sovereign debt, declines in oil and commodity prices, dramatic changes in currency exchange rates, and public sentiment. In addition, many governments and quasi- governmental entities throughout the world have responded to the turmoil with a variety of significant fiscal and monetary policy changes, including, but not limited to, direct capital infusions into companies, new monetary programs, and dramatically lower interest rates.

The COVID-19 pandemic and efforts to contain its spread have negatively affected, and are likely to continue to negatively affect, the global economy, the economies of the United States and other individual countries, and the financial performance of individual issuers, sectors, industries, asset classes, and markets in significant and unforeseen ways. This coronavirus has resulted in closing borders, enhanced health screenings, healthcare service preparation and delivery, quarantines, cancellations, disruptions to supply chains and customer activity, as well as general concern and uncertainty. In addition, the impact of infectious diseases in developing or emerging market countries may be greater due to less established health care systems. Health crises caused by the recent coronavirus outbreak may exacerbate other pre-existing political, social and economic risks in certain countries. The impact of the outbreak may be short term or may last for an extended period of time.

While the extreme volatility and disruption that U.S. and global markets experienced for an extended period of time beginning in 2007 and 2008 had, until the coronavirus outbreak, generally subsided, uncertainty and periods of volatility still remained, and risks to a robust resumption of growth persist. Federal Reserve policy, including with respect to certain interest rates may adversely affect the value, volatility and liquidity of dividend and interest paying securities. Market volatility, dramatic changes to interest rates and/or a return to unfavorable economic conditions may lower the Fund's performance or impair the Fund's ability to achieve its investment objective.

The United Kingdom left the European Union ("EU") on January 31, 2020 (commonly referred to as "Brexit"). During an 11 month transition period, ending December 31, 2020, the United Kingdom and the EU agreed to a Trade and Cooperation Agreement which sets out the agreement for certain parts of the future relationship between the EU and the United Kingdom from January 1, 2021. The Trade and Cooperation Agreement does not provide the United Kingdom with the same level of rights or access to all goods and services in the EU as the United Kingdom previously maintained as a member of the EU and during the transition period. In particular, the Trade and Cooperation Agreement does not include an agreement on financial services. Accordingly, uncertainty remains in certain areas as to the future relationship between the United Kingdom and EU. The uncertainty caused by the United Kingdom's departure from the EU could lead to prolonged political, legal, regulatory, tax and economic uncertainty and wider instability and volatility in the financial markets of the United Kingdom and more broadly across Europe. It may also lead to weakening corporate and financial confidence in such markets as the United Kingdom renegotiates the regulation of the provision of financial services within and to persons in the EU. Brexit could lead to market dislocation, heightened counterparty risk, an adverse effect on the management of market risk and, in particular, asset and liability management due in part to redenomination of financial assets and liabilities, an adverse effect on the management, operation and investment in the Fund and increased legal, regulatory or compliance burden for the Fund which may have a negative impact on the operations, financial condition, returns and prospectus of the Fund.

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A number of countries in Europe have suffered terror attacks, and additional attacks may occur in the future. Ukraine has experienced ongoing military conflict; this conflict may expand and military attacks could occur elsewhere in Europe. Europe has also been struggling with mass migration from the Middle East and Africa. The ultimate effects of these events and other socio-political or geographical issues are not known but could profoundly affect global economies and markets.

Russia also may attempt to assert its influence in the region through economic or even military measures, as it did with Georgia in the summer of 2008 and the Ukraine in 2014 and 2022. Russia launched a large-scale invasion of Ukraine on February 24, 2022. The extent and duration of the military action, resulting sanctions and resulting future market disruptions in Europe and globally, including declines in its stock markets and the value of the ruble against the U.S. dollar, are impossible to predict, but could be significant and have a severe adverse effect on Russia and Europe in general. Any such disruptions caused by Russian military action or other actions (including cyber- attacks and espionage) or resulting actual and threatened responses to such activity, including purchasing and financing restrictions, boycotts or changes in consumer or purchaser preferences, sanctions, tariffs or cyber-attacks on the Russian government, Russian companies or Russian individuals, including politicians, may negatively impact Russia's economy and Russian issuers of securities in which the Fund invests. Actual and threatened responses to such military action may also impact the markets for certain Russian commodities, such as oil and natural gas, as well as other sectors of the Russian economy, and may likely have collateral impacts on such sectors in Europe and globally. It is also possible that this conflict could expand and attacks could occur elsewhere in Europe. The potential for wider conflict may increase financial market volatility and could have severe adverse effects on regional and global markets. These and any related events could have significant impact on Fund performance and the value of an investment in the Fund.

As a result of political and military actions undertaken by Russia, the U.S. and the EU have instituted sanctions against certain Russian officials and companies. These sanctions and any additional sanctions or other intergovernmental actions that may be undertaken against Russia in the future may result in the devaluation of Russian currency, a downgrade in the country's credit rating, and a decline in the value and liquidity of Russian securities. Such actions could result in a freeze of Russian securities, impairing the ability of a fund to buy, sell, receive, or deliver those securities. Retaliatory action by the Russian government could involve the seizure of US and/or European residents' assets, and any such actions are likely to impair the value and liquidity of such assets. Any or all of these potential results could have an adverse/recessionary effect on Russia's economy. All of these factors could have a negative effect on the performance of funds that have significant exposure to Russia.

In addition, policy and legislative changes in the United States and in other countries are changing many aspects of financial regulation. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Widespread disease and virus epidemics, such as the coronavirus outbreak, could likewise be highly disruptive, adversely affecting individual companies, sectors, industries, markets, currencies, interest and inflation rates, credit ratings, investor sentiment, and other factors affecting the value of the Fund's investments.

Portfolio security holdings disclosure

A description of the Fund's policies and procedures in connection with the disclosure of portfolio security holdings of the Fund is available in the Fund's SAI at www.calamos.com.

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Who manages the Fund?

Investment Adviser

The Fund is advised by Calamos Advisors LLC ("Calamos Advisors" or the "Advisor"), 2020 Calamos Court, Naperville, Illinois 60563. Calamos Advisors, an investment adviser registered with the SEC effective May 29, 1987, is a wholly owned subsidiary of Calamos Investments LLC ("CILLC"). CILLC's assets under management as of June 30, 2023, were $36 billion ($34 billion of which represented Calamos Advisors' assets under management). Calamos Asset Management, Inc. ("CAM") is the sole manager of CILLC. As of December 31, 2022, approximately 22% of the outstanding interests of CILLC was owned by CAM and the remaining approximately 78% of CILLC was owned by Calamos Partners LLC ("CPL") and John P. Calamos, Sr. CAM was owned by John P. Calamos, Sr. and John S. Koudounis, and CPL was owned by John S. Koudounis and Calamos Family Partners, Inc. ("CFP"). CFP was beneficially owned by members of the Calamos family, including John P. Calamos, Sr.

Subject to the overall authority of the Board of Trustees, Calamos Advisors provides continuous investment supervision and management to the Fund under a management agreement and also furnishes office space, equipment and management personnel. For these services, the Fund pays Calamos Advisors a fee based on its average daily net assets, which is accrued daily and paid on a monthly basis. The Fund will pay fees (before any reimbursement) under the management agreement in the following amounts as a percentage of its average net assets:

ETF

 

FEES

 

Calamos Convertible Equity Alternative ETF

   

0.69

%

 

Out of this management fee, Calamos Advisors pays substantially all expenses of the Fund, including the cost of transfer agency, custody, fund administration, legal, audit and other service and license fees, except for distribution and service fees payable pursuant to a Rule 12b-1 plan, if any, acquired fund fees and expenses brokerage commissions and other expenses connected with the execution of portfolio transactions, taxes, interest, and extraordinary expenses.

At a meeting held on September 1, 2023, the Board of Trustees approved the Investment Management Agreement for the Fund. A discussion regarding the basis for the Board's approval of the Investment Management Agreement on behalf of the Fund will be included in the first shareholder report that covers the period in which the Fund commences operations.

Portfolio Managers

John Hillenbrand. John Hillenbrand joined Calamos Advisors in 2002 and since September 2015 is a Co-CIO, Head of Multi-Asset Strategies and Co-Head of Convertible Strategies, as well as a Senior Co-Portfolio Manager. From March 2013 to September 2015 he was a Co-Portfolio Manager. Between August 2002 and March 2013 he was a senior strategy analyst.

Joe Wysocki. Joe Wysocki joined Calamos Advisors in October 2003 and since February 2021 is a Senior Co-Portfolio Manager. Previously, he was a Co-Portfolio Manager from March 2015 to February 2021; a sector head from March 2014 to March 2015; a Co-Portfolio Manager from March 2013 to March 2014; and a senior strategy analyst from February 2007 and March 2013.

Jon Vacko. Jon Vacko joined Calamos Advisors in 2000 and has been a Senior Co-Portfolio Manager since September 2015. Previously, he was a Co-Portfolio Manager from August 2013 to September 2015; prior thereto he was a Co-Head of Research and Investments from July 2010 to August 2013.

The Fund's SAI provides additional information about each portfolio manager, including other accounts they manage, their ownership in the Calamos Family of Funds and their compensation.

Management Approach

Calamos Advisors employs a "team of teams" approach to portfolio management, led by the Global CIO and our CIO team consisting of 5 Co-CIOs with specialized areas of investment expertise. The Global CIO and Co-CIO team are responsible for oversight of investment team resources, investment processes, performance and risk. As heads of investment verticals, Co-CIOs manage investment team members and, along with Co- Portfolio Managers and Associate Portfolio Managers, have day-to-day

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Fund Facts

portfolio oversight and construction responsibilities of their respective investment strategies. While investment research professionals within each Co-CIO's team are assigned specific strategy responsibilities, they also provide support to other investment team verticals, creating deeper insights across a wider range of investment strategies. The combination of specialized investment teams with cross team collaboration results in what we call our team of teams approach.

This team of teams approach is further reflected in the composition of Calamos Advisors' Investment Committee, made up of the Global CIO, the Co-CIO team, and the Global Head of Trading. Other members of the investment team participate in Investment Committee meetings in connection with specific investment related issues or topics as deemed appropriate.

The structure and composition of the Investment Committee results in a number of benefits, as it:

•  Leads to broader perspective on investment decisions: multiple viewpoints and areas of expertise feed into consensus;

•  Promotes collaboration between teams; and

•  Functions as a think tank with the goal of identifying ways to outperform the market on a risk-adjusted basis.

The objectives of the Investment Committee are to:

•  Form the firm's top-down macro view, market direction, asset allocation, and sector/country positioning.

•  Establish firm-wide secular and cyclical themes for review.

•  Review firm-wide and portfolio risk metrics, recommending changes where appropriate.

•  Review firm-wide, portfolio and individual security liquidity constraints.

•  Evaluate firm-wide and portfolio investment performance.

•  Evaluate firm-wide and portfolio hedging policies and execution.

•  Evaluate enhancements to the overall investment process.

John Hillenbrand, Jon Vacko, and Joe Wysocki are each Senior Co-Portfolio Managers of the Fund. Senior Co- Portfolio Managers are collectively referred to within this registration statement as "Portfolio Managers".

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange under the symbol CVRT and individual Fund Shares may only be purchased and sold in the secondary market through a broker-dealer. The Exchange and secondary markets are closed on weekends and also are generally closed on the following holidays: New Year's Day, Dr. Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day (observed), Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Exchange may close early on the business day before certain holidays and on the day after Thanksgiving Day. Exchange holiday schedules are subject to change without notice. If you buy or sell Fund Shares in the secondary market, you will pay the secondary market price for Fund Shares. In addition, you may incur customary brokerage commissions and charges and may pay some or all of the spread between the bid and the offered price in the secondary market on each leg of a round trip (purchase and sale) transaction.

The trading prices of Fund Shares will fluctuate continuously throughout trading hours based on market supply and demand rather than the relevant Fund's net asset value, which is calculated at the end of each business day. Fund Shares will trade on the Exchange at prices that may be above (i.e., at a premium) or below (i.e., at a discount), to varying degrees, the daily net asset value of Fund Shares. The trading prices of Fund Shares may deviate significantly from the Fund's net asset value during periods of market volatility. Given, however, that Fund Shares can be issued and redeemed daily in Creation Units, the Adviser believes that large discounts and premiums to net asset value should not be sustained over long periods.

Authorized Participants may acquire shares directly from the Fund, and Authorized Participants may tender their shares for redemption directly to the Fund, at NAV per share only in Creation Units. Purchases and redemptions directly with the Fund must follow the Fund's procedures, which are described in the SAI.

The Fund may liquidate and terminate at any time without shareholder approval.

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Book Entry

Fund 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 record owner of all outstanding Shares of the Fund and is recognized as the owner of all Shares for all purposes.

Investors owning Fund Shares are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for all Fund 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 Fund Shares, you are not entitled to receive physical delivery of stock certificates or to have Fund Shares registered in your name, and you are not considered a registered owner of Fund Shares. Therefore, to exercise any right as an owner of Fund Shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book entry or "street name" form.

Fund Share Trading Prices

The trading prices of Shares of the Fund on the Exchange may differ from the Fund's daily NAV. Market forces of supply and demand, economic conditions and other factors may affect the trading prices of Shares of the Fund.

The approximate value of Shares of the Fund, an amount representing on a per share basis the sum of the current market price of the cash or securities, as applicable, accepted by the Fund in exchange for Shares of the Fund and an estimated cash component, if any, is disseminated every 15 seconds throughout the trading day through the facilities of the Consolidated Tape Association. This approximate value should not be viewed as a "real-time" update of the NAV per Share of the Fund because the approximate value may not be calculated in the same manner as the NAV, which is computed once a day, generally at the end of the business day. The Fund is not involved in, or responsible for, the calculation or dissemination of the approximate value of the Fund Shares and the Fund does not make any warranty as to its accuracy.

Frequent Purchases and Redemptions of Fund Shares

Shares of the Fund may be purchased and redeemed directly from the Fund only in Creation Units by Authorize Participants. The vast majority of trading in Shares of the Fund occurs on the secondary market, and does not involve the Fund directly. In-kind purchases and redemptions of Creation Units by Authorized Participants and cash trades on the secondary market are unlikely to cause many of the harmful effects of frequent purchases and/or redemptions of Fund Shares. Cash purchases and/or redemptions of Creation Units, however, can result in disruption of portfolio management, dilution to the Fund and increased transaction costs, which could negatively impact the Fund's ability to achieve its investment objective, and may lead to the realization of capital gains. These consequences may increase as the frequency of cash purchases and redemptions of Creation Units by Authorized Participants increases. However, direct trading by Authorized Participants is critical to ensuring that Fund Shares trade at or close to NAV.

The Fund imposes no restrictions on the frequency of purchases and redemptions ("market timing"). To minimize these potential consequences of frequent purchases and redemptions of Fund Shares, the Fund employs fair valuation pricing, and imposes transaction fees on purchases and redemptions of Creation Units to cover the custodial and other costs the Fund incurs in effecting trades. In addition, the Adviser monitors trades by Authorized Participants for patterns of abusive trading and the Fund reserves the right to not accept orders from Authorized Participants that the Adviser has determined may be disruptive to the management of the Fund, or otherwise are not in the best interests of the Fund. For these reasons, the Board has not adopted policies and procedures with respect to frequent purchases and redemptions of Fund Shares. The Trust's policies and procedures regarding frequent purchases and redemptions may be modified by the Board of Trustees at any time.

The Trust's policies and procedures prohibit the practice of any officer or employee of the Trust, a Trust investment adviser (including any sub-adviser), the distributor, custodian, or transfer agent, or other affiliated person of the Trust placing orders to purchase or redeem shares of a series of the Trust after the designated time as of which the Fund calculates its NAV (i.e. "late trading").

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Fund Facts

Distribution and Service Plan

The Fund has adopted a distribution and service plan ("Plan") pursuant to Rule 12b-1 under the Investment Company 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 Investment Company Act.

No distribution or service fees are currently paid by the Fund, however, and there are no current plans to impose these fees. In the event Rule 12b-1 fees are charged, over time they would increase the cost of an investment in the Fund because they would be paid on an ongoing basis.

Fund Website and Disclosure of Portfolio Holdings

The Trust maintains a website for the Fund at www.calamos.com. Among other things, this website includes this Prospectus and the SAI, and will include the Fund's holdings, the Fund's last annual and semi-annual reports (when available), pricing information about Fund Shares trading on the Exchange, daily NAV calculations and a historical comparison of the trading prices to NAV.

Each day the Fund is open for business, the Trust publicly disseminates the Fund's full portfolio holdings as of the close of the previous day through its website at www.calamos.com. A description of the Trust's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's SAI.

Dividends, Other Distributions and Taxes

Fund Distributions

The Fund generally pays out dividends from its net investment income, if any, to shareholders monthly, and distributes its net capital gains, if any, to shareholders annually. The Fund typically earns dividends from stocks in which it invests. These amounts, net of expenses, are passed along to Fund shareholders as "income dividends." The Fund realizes capital gains or losses whenever it sells securities. Net long-term capital gains are distributed to shareholders as "capital gain dividends."

Brokers may make available to their customers who own Fund 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 Fund Shares of the Fund purchased in the secondary market. Without this service, investors would receive their distributions in cash.

Taxes

As with any investment, you should consider how your investment in Fund Shares of the Fund will be taxed. The tax information in this prospectus is provided only as general information. This section is current as of the date of this prospectus. Tax laws and interpretations change frequently, and these summaries do not describe all of the tax consequences to all taxpayers. For example, these summaries generally do not describe your situation if you are a corporation, a non-U.S. person, a broker-dealer, or other investor with special circumstances. However, with respect to certain tax issues, the summaries describe the general tax treatment of certain distributions made to corporations and non-U.S. persons. In addition, this section does not describe your state, local or non-U.S. tax consequences. You should consult your own tax advisor about the tax consequences of an investment in Fund Shares.

Fund distributions to you and the sale or redemption of your Shares in the Fund will have tax consequences to you. Such consequences may be different if you hold your Shares through a tax-exempt entity or tax-advantaged retirement account, such as an individual retirement account or 401(k) plan.

The Fund intends to elect, and intends to qualify each year, as a regulated investment fund (a "RIC") under the Internal Revenue Code of 1986, as amended (the "Code"). As a RIC, the Fund is generally not subject to corporate-level U.S. federal income tax on any net ordinary income or capital gains that are timely distributed to shareholders. However, the Fund's failure to qualify as a RIC or to meet minimum distribution requirements would result (if certain relief provisions were not available) in corporate-level taxation and, consequently, a reduction in amounts available for distribution to shareholders.

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Fund Facts

Taxes on Distributions

Distributions by the Fund generally are taxable to you as ordinary income or capital gains. Distributions are subject to federal income tax, whether received in cash or reinvested in additional Fund Shares or shares of another fund, and may be subject to state or local taxes. Distributions of the Fund's "investment company taxable income" generally will be taxable as ordinary income to the extent of the Fund's current or accumulated earnings and profits. Notwithstanding the foregoing, distributions that are attributable to "qualified dividends" received by the Fund may be eligible to be taxed at long-term capital gains rates, as long as the Fund and the shareholder meet certain holding period requirements.

Distributions of the Fund's net capital gain that are properly reported by the Fund as "capital gain dividends" will generally be taxable to you as long-term capital gains, currently at a maximum rate of 20%, regardless of your holding period in the Fund's Shares. Distributions in excess of the Fund's current and accumulated earnings and profits first will reduce your adjusted tax basis in your Fund Shares and, after the adjusted basis is reduced to zero, will constitute capital gain. Such capital gain will be long-term capital gain and thus, will be taxed at a maximum rate of 20%, if the distributions are attributable to Fund Shares that you have held for more than one year.

Certain non-corporate taxpayers will also be subject to a 3.8% U.S. federal Medicare contribution tax with respect to the lesser of (1) their "net investment income" or (2) the excess of their "modified adjusted gross income" over a threshold amount ($200,000 for single taxpayers and $250,000 for taxpayers who are married and filing jointly).

Corporate shareholders of the Fund are generally eligible for a dividends-received deduction with respect to ordinary income dividends (but not capital gain dividends) properly designated as eligible for such deduction by the Fund, as long as the Fund and the corporate shareholder meet certain holding period and other requirements.

Under a dividend reinvestment service, you may have the option to have all cash distributions automatically reinvested in additional Fund Shares. Any distributions reinvested under such a service will nevertheless be taxable to you as described above.

You will have an adjusted basis in the additional Fund Shares purchased through such a reinvestment service equal to the amount of the reinvested distribution plus the amount of any fees charged for the transaction. The additional Fund Shares will have a holding period commencing on the day following the day on which they are credited to your account.

A distribution will reduce the Fund's NAV per Share and generally will be taxable to you as ordinary income or capital gain even if it is paid from income or gains earned by the Fund before you invested in the Fund and thus, from an investment standpoint, constitutes a return of capital. In general, distributions are subject to federal income tax as of the date of payment. However, distributions paid in January will be treated as paid on December 31 of the prior year if they were declared and payable to shareholders of record on a date in October, November or December of the prior year.

The Fund's investments in certain debt instruments could cause the Fund to recognize taxable income in excess of the cash generated by such investments, which may require the Fund to dispose of other investments in order to make required distributions.

The Fund's transactions in derivatives, as well as any of its hedging, short sale, securities loan or similar transactions may be subject to one or more special tax rules. These rules may affect whether gains and losses recognized by the Fund are treated as ordinary or capital, accelerate the recognition of income or gains to the Fund, defer losses to the Fund, and cause adjustments in the holding periods of the Fund's securities, thereby affecting whether capital gains and losses are treated as short-term or long-term. These rules could therefore affect the amount, timing and/or character of distributions to shareholders and thus taxes payable by shareholders.

You may be subject to federal back-up withholding tax, if you do not provide the Fund with a taxpayer identification number (for an individual, a social security number) and make other required certifications, or the Internal Revenue Service informs the Fund that your tax identification number is incorrect. Backup withholding is not an additional tax. You may claim the amount withheld as a credit on your federal income tax return, provided you furnish the appropriate information to the Internal Revenue Service.

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Fund Facts

Taxes When Shares are Sold

Any capital gain or loss realized upon a sale of Fund Shares is generally treated as long-term capital gain or loss if you have held the Fund Shares for more than one year and as short-term capital gain or loss if you have held the Fund Shares for one year or less. The ability to deduct capital losses realized on a sale of Fund Shares may be limited.

Taxes on Purchase and Redemption of Creation Units

An Authorized Participant that exchanges equity securities for Creation Units will generally recognize a gain or a loss on the exchange. Any such gain or loss will be equal to the difference between the market value of the Creation Units at the time of the exchange, plus (or minus) the cash amount received (or paid), and such Authorized Participant's aggregate basis in the securities surrendered. A person who redeems Creation Units for equity securities will generally recognize a gain or loss equal to the difference between the aggregate market value of the securities received, plus (or minus) any cash received (or paid), and such person's basis in the Creation Units redeemed. The Internal Revenue Service, however, may assert that a loss realized upon an exchange of securities for Creation Units cannot be deducted currently under the rules governing "wash sales," or on the basis that there has been no significant change in the Authorized Participant's economic position with respect to such Creation Units. Persons exchanging securities should consult their own tax advisor with respect to the applicability of the wash sale rules and the availability and timing of a deduction for any loss.

Any capital gain or loss realized upon a redemption of Creation Units is generally treated as long-term capital gain or loss if the Creation Units have been held for more than one year and as short-term capital gain or loss if the Creation Units have been held for one year or less. If you purchase or redeem Creation Units, you will be sent a confirmation statement showing how many Fund Shares you purchased or sold and at what price.

Treatment of Fund Expenses

Expenses incurred and deducted by the Fund will generally not be treated as income taxable to you.

Non-U.S. Taxes

Income and proceeds received by the Fund from sources within foreign countries may be subject to withholding and other taxes imposed by such countries, which would reduce the Fund's return on investments in such countries. Tax treaties between certain countries and the U.S. may reduce or eliminate such taxes. Shareholders generally will not be entitled separately to claim a credit or deduction in respect of non-U.S. taxes paid or treated as paid by the Fund. In addition, the Fund's investments in foreign securities or foreign currencies may increase or accelerate the Fund's recognition of ordinary income and may affect the timing or amount of the Fund's distributions.

Non-U.S. Investors

If you are a non-U.S. investor (i.e., an investor other than a U.S. citizen or resident or a U.S. corporation, partnership, estate or trust), you should be aware that, generally, subject to applicable tax treaties, distributions from the Fund will be characterized as dividends for U.S. federal income tax purposes (other than dividends which the Fund properly reports as capital gain dividends) and will be subject to U.S. federal income taxes, including withholding taxes, subject to certain exceptions described below. However, distributions received by a non-U.S. investor from the Fund that are properly reported by the Fund as capital gain dividends may not be subject to U.S. federal income taxes, including withholding taxes, provided that the Fund makes certain elections and certain other conditions are met. Distributions from the Fund that are properly reported by the Fund as an interest-related dividend attributable to certain interest income received by the Fund or as a short-term capital gain dividend attributable to certain net short-term capital gain income received by the Fund may not be subject to U.S. federal income taxes, including withholding taxes when received by certain non-U.S. investors, provided that the Fund makes certain elections and certain other conditions are met.

Distributions may be subject to a U.S. withholding tax of 30% in the case of distributions to (i) certain non-U.S. financial institutions that have not entered into an agreement with the U.S. Treasury to collect and disclose certain information and are not resident in a jurisdiction that has entered into such an agreement with the U.S. Treasury and (ii) certain other non-U.S. entities that do not provide certain certifications and information about the entity's U.S. owners. The Internal Revenue Service and the Department of Treasury have issued proposed regulations providing that these withholding rules will not be applicable to the gross proceeds of share redemptions or capital gains dividends that the Fund pays.

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Fund Facts

Investments in Certain Non-U.S. Corporations

If the Fund holds an equity interest in any "passive foreign investment companies" ("PFICs"), which are generally certain non-U.S. corporations that receive at least 75% of their annual gross income from passive sources (such as interest, dividends, certain rents and royalties or capital gains) or that hold at least 50% of their assets in investments producing such passive income, the Fund could be subject to U.S. federal income tax and additional interest charges on gains and certain distributions with respect to those equity interests, even if all the income or gain is timely distributed to its shareholders. The Fund will not be able to pass through to its shareholders any credit or deduction for such taxes. The Fund may be able to make an election that could ameliorate these adverse tax consequences. For instance, the Fund may elect to mark the gains (and to a limited extent losses) in such holdings "to the market" as though it had sold (and, solely for purposes of this mark-to-market election, repurchased) its holdings in those PFICs on the last day of the Fund's taxable year. If the Fund were to make a mark-to-market election, it would recognize as ordinary income any increase in the value of such PFIC shares, and as ordinary loss any decrease in such value to the extent it did not exceed prior increases included in income. Under this election, the Fund might be required to recognize in a year income in excess of its distributions from PFICs and its proceeds from dispositions of PFIC stock during that year, and such income would nevertheless be subject to the distribution requirement and would be taken into account for purposes of the 4% excise tax that may be imposed on the undistributed income of a RIC. Dividends paid by PFICs are not treated as qualified dividend income.

Other Tax Matters

The foregoing is only a summary of certain federal income tax considerations of investing in the Fund under current law, which is subject to change in the future. Shareholders who are not U.S. persons within the meaning of the Code, such as non-resident aliens, foreign trusts or estates, or foreign corporations or partnerships may be subject to different U.S. federal income tax treatment.

You may also be subject to state and local taxes on distributions paid by the Fund, and sales and redemptions of Fund Shares. You should consult your tax advisor for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific tax situation. More information about taxes can be found in the Fund's SAI.

Net Asset Value

The NAV of shares is determined at the close of regular trading on the New York Stock Exchange (normally 4:00 p.m. Eastern Time) on each day the New York Stock Exchange ("NYSE") is open. NAV is computed by determining the aggregate market value of all assets of the Fund, less its liabilities, divided by the total number of shares outstanding ((assets-liabilities)/number of shares = NAV). The NYSE is closed on weekends and 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. The NAV takes into account the expenses and fees of the Fund, including management fees, which are accrued daily. The determination of NAV for the Fund for a particular day is applicable to all applications for the purchase of shares, as well as all requests for the redemption of shares, received by the Fund (or an authorized broker or agent, or its authorized designee) before the close of trading on the NYSE on that day.

Generally, securities traded or dealt in upon one or more securities exchanges (whether domestic or foreign) for which market quotations are readily available and not subject to restrictions against resale shall be valued at the last quoted sales price on the primary exchange or, in the absence of a sale on the primary exchange, at the mean between the current bid and ask prices on such exchange. Securities primarily traded in the National Association of Securities Dealers' Automated Quotation System ("NASDAQ") National Market System for which market quotations are readily available shall be valued using the NASDAQ official closing price. Securities that are not traded or dealt in any securities exchange (whether domestic or foreign) and for which over-the-counter market quotations are readily available generally shall be valued at the last sale price or, in the absence of a sale, at the mean between the current bid and ask price on such over-the-counter market. Debt securities not traded on an exchange may be valued at prices supplied by a pricing agent (s) based on broker or dealer supplied valuations or matrix pricing, a method of valuing securities by reference to the value of other securities with similar characteristics, such as rating, interest rate and maturity. Futures, swaps and options contracts listed for trading on a futures or options exchange or board of trade for which market quotations are generally available are valued at the last quoted sale price, or, in the absence of a sale,

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Fund Facts

at the mean of the last bid and ask price. Total return swaps on exchange-listed securities are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price.

Securities held by the Fund are valued in accordance with policies and procedures established by the Adviser pursuant to Rule 2a-5 under the Investment Company Act of 1940 ("1940 Act") and approved by and subject to the oversight of the Board of Trustees ("Valuation Procedures"). If market quotations are not readily available, securities or other assets will be valued at their fair value as determined in good faith by the Adviser in accordance with procedures approved by the Board and evaluated by the Board as to the reliability of the fair value method used. In these cases, the Fund's NAV will reflect certain portfolio securities' fair values rather than their market prices. Fair value pricing involves subjective judgments, and it is possible that the fair value determined for a security or other asset may be materially different than the value that could be realized upon the sale of that security or other asset. The fair value prices can differ from market prices. The Board of Trustees has designated Calamos Advisors as "valuation designee" for the Fund. The valuation designee is responsible for determining the value of the Fund's investments. The designee may also enlist third party consultants such as an audit firm or financial officer of a security issuer on an as-needed basis to assist in determining a security-specific fair value. The Board reviews and ratifies the execution of this process and the resultant fair value prices at least quarterly to assure the process produces reliable results.

The Fund may use independent pricing services to assist in calculating the value of the Fund's securities or other assets.

With respect to any portion of the Fund's assets that are invested in one or more open-end management investment companies registered under the 1940 Act, the Fund's net asset value is calculated based upon the net asset values of those open-end management investment companies, and the prospectuses for these companies explain the circumstances under which those companies will use fair value pricing and the effects of using fair value pricing.

Fund Service Providers

State Street Bank and Trust Company ("State Street"), located at One Congress Street, Suite 1, Boston, Massachusetts 02114-2016, serves as the Fund's administrator, custodian, fund accounting and financial accounting agent, and transfer agent.

Foreside Fund Services, LLC, an affiliate of Foreside Financial Group, LLC (d/b/a ACA Group) (the "Distributor"), located at Three Canal Plaza, Suite 100, Portland, ME 04101, serves as the distributor of Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in Fund Shares.

Deloitte & Touche LLP, located at 111 South Wacker Drive, Chicago, IL 60606, 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.

Ropes & Gray LLP, located at 191 North Wacker Drive, 32nd​ Floor, Chicago, IL 60606, serves as legal counsel to the Trust.

Premium/Discount Information

Information showing the number of days the market price of the Fund Shares was greater (at a premium) and less (at a discount) than the Fund's NAV for the most recently completed calendar year, and the most recently completed calendar quarters since that year (or the life of the Fund, if shorter), is available at www.calamos.com.

Investments by Other Investment Companies

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies, including Fund Shares. The SEC adopted Rule 12d1-4 under the 1940 Act on November 19, 2020, which became effective January 19, 2021. The Fund is required to comply with the conditions of Rule 12d1-4, which allows, subject to certain conditions, the Fund to invest in other registered investment companies and other registered investment companies to invest in the Fund beyond the limits contained in Section 12(d)(1) of the 1940 Act.

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Financial Highlights

The Fund is new and has no performance history as of the date of this prospectus. Financial information is therefore not available.

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Other Information

Continuous Offering

The method by which Creation Units of Fund Shares are created and traded may raise certain issues under applicable securities laws. Because new Creation Units of Fund Shares are issued and sold by the Fund on an ongoing basis, a "distribution," as such term is used in the Securities Act of 1933, as amended (the "Securities Act"), may occur at any point. Broker-dealers and other persons are cautioned that some activities on their part may, depending on the circumstances, result in their being deemed participants in a distribution in a manner which could render them statutory underwriters and subject them to the prospectus delivery requirements and liability provisions of the Securities Act. For example, a broker-dealer firm or its client may be deemed a statutory underwriter if it takes Creation Units after placing an order with the Distributor, breaks them down into constituent Fund Shares and sells the Fund Shares directly to customers or if it chooses to couple the creation of a supply of new Fund Shares with an active selling effort involving solicitation of secondary market demand for Fund Shares. A determination of whether one is an underwriter for purposes of the Securities Act must take into account all the facts and circumstances pertaining to the activities of the broker-dealer or its client in the particular case, and the examples mentioned above should not be considered a complete description of all the activities that could lead to a characterization as an underwriter.

Broker-dealer firms should also note that dealers who are not "underwriters" but are effecting transactions in Fund Shares, whether or not participating in the distribution of Fund 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 Investment Company Act of 1940, as amended (the "Investment Company Act"). As a result, broker-dealer firms should note that dealers who are not "underwriters" but are participating in a distribution (as contrasted with engaging in ordinary secondary market transactions) and thus dealing with the Fund Shares that are part of an overallotment 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.

Summary of Certain Provisions of the Second Amended and Restated Trust Instrument

The summary below is a synopsis of certain provisions contained in the Trust's Second Amended and Restated Trust Instrument (the "Trust Instrument"). Shareholders should refer to the Trust Instrument for further information. Defined terms have the meanings contained in the Trust Instrument.

Derivative Actions

The Second Amended and Restated Trust Instrument (the "Trust Instrument") requires, within Section 9 of Article IV, that before bringing any derivative action on behalf of the Fund, Shareholders must have made a written demand to the Board of Trustees requesting that they cause the Trust or affected Series or Class, as applicable, to file the action itself.

In order to warrant consideration, any such written demand must include at least the following:

(1)  a detailed description of the action or failure to act complained of and the facts upon which each such allegation is made;

(2)  a statement to the effect that the complaining Shareholders believe that they will fairly and adequately represent the interests of similarly situated Shareholders in enforcing the right of the Trust or the affected Series or Class, as applicable and an explanation of why the complaining Shareholders believe that to be the case;

(3)  a certification that the following requirements have been met, as well as information reasonably designed to allow the Trustees to verify that certification:

(a)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, at the time of the action or failure to act complained of, or acquired the Shares afterwards by operation of law from a Person who was a Shareholder at that time; and

(b)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, as of the time the demand required by Section 9 of Article IV was made; and

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Other Information

(4)  a certification that each complaining Shareholder will be a Shareholder of the Trust or the affected Series or Class, as applicable as of the commencement of the derivative action.

The Trust Instrument further provides that at least 10% of the Shareholders of the Trust or the affected Series or Class, as applicable, must join in bringing the derivative action. This provision does not apply to claims brought under the federal securities laws.

The Trust Instrument also provides that a copy of the derivative complaint must be served on the Trust, assuming the requirements described above have already been met and the derivative action has not been barred as further described in the Trust Instrument.

Forum and Waiver of Jury Trial

Section 10 of Article X of the Trust Instrument outlines which shareholder actions must be brought in state court and which must be brought in federal court. This section states in particular that, unless the Trust consents in writing to the selection of an alternative forum, the Federal District Courts of the United States of America shall be the sole and exclusive forum for the resolution of any complaint asserting a cause of action arising under any federal securities law. This provision may increase costs for a shareholder to bring a claim or may limit a shareholder's ability to bring a claim in a judicial forum that they find more convenient or favorable. While the enforceability of the exclusive forum provisions may be challenged, this section also provides that if any provisions of Section 10 shall be held to be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining portions will still apply.

Section 10 of Article X of the Trust Instrument also states that shareholders and all other such persons bringing any such suit, action, or proceeding in the Superior Court in the State of Delaware waive the right to a trial by jury to the fullest extent permitted by law.

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For more detailed information on the Fund, several additional sources of information are available to you. The Fund's SAI, incorporated by reference into this prospectus, contains detailed information on the Fund's policies and operation. Additional information about the Fund's investments is available in the annual and semi-annual reports to shareholders. In the Fund's annual reports, you will find a discussion of the market conditions and investment strategies that significantly impacted the Fund's performance during the last fiscal year. The Fund's most recent SAI, annual or semi-annual reports and certain other information are available free of charge by calling the Fund at (866) 363-9219, on the Fund's website at www.calamos.com or through your financial advisor. Shareholders may call the toll-free number above with any inquiries.

You may obtain this and other information regarding the Fund, including the SAI and Codes of Ethics adopted by the Adviser, Distributor and the Trust, directly from the SEC. Information on the SEC's website is free of charge. Visit the SEC's on-line EDGAR database at http://www.sec.gov. You may also request information regarding the Fund by sending a request (along with a duplication fee) to the SEC by sending an electronic request to [email protected].

Calamos Convertible Equity Alternative ETF

2020 Calamos Court
Naperville, IL 60563-2787
866.363.9219

www.calamos.com

SEC File #333-191151
#811-22887

CVRTSTAPRO 100223