# EDGAR Filing Document

**Accession Number:** 0001579881
**File Stem:** 0001104659-25-115868
**Filing Date:** 2025-11
**Character Count:** 114812
**Document Hash:** e86b32cbc7cba7bde9329ee910c92401
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-115868.hdr.sgml**: 20251125

**ACCESSION NUMBER**: 0001104659-25-115868

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 5

**FILED AS OF DATE**: 20251125

**DATE AS OF CHANGE**: 20251125

**EFFECTIVENESS DATE**: 20251125

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Calamos ETF Trust
- **CENTRAL INDEX KEY:** 0001579881

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-191151
- **FILM NUMBER:** 251517422

**BUSINESS ADDRESS:**
- **STREET 1:** 2020 CALAMOS COURT
- **CITY:** NAPERVILLE
- **STATE:** IL
- **ZIP:** 60563
- **BUSINESS PHONE:** 630-245-8394

**MAIL ADDRESS:**
- **STREET 1:** 2020 CALAMOS COURT
- **CITY:** NAPERVILLE
- **STATE:** IL
- **ZIP:** 60563

## Series and Classes Contracts Data

### Calamos Antetokounmpo Global Sustainable Equities ETF (Series ID: S000079464)

---

|  |  |
|:---|:---|
| Class Name                                            | Class ID   |
| Calamos Antetokounmpo Global Sustainable Equities ETF | C000240501 |

---

## Series and Classes Contracts Data

### Calamos Antetokounmpo Global Sustainable Equities ETF (Series ID: S000079464)

| Class ID   | Class Name                                            | Ticker Symbol   |
|:---|:---|:---|
| C000240501 | Calamos Antetokounmpo Global Sustainable Equities ETF |  |

![](j25294262_ac001.jpg)

![](j25294262_ac002.jpg)

Calamos Antetokounmpo Global Sustainable Equities ETF (NYSE Arca—SROI)

Prospectus November 28, 2025

Calamos Antetokounmpo Global Sustainable Equities 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.**

• Calamos Antetokounmpo Asset Management LLC ("CGAM") serves as the adviser ("Adviser") to the Calamos Antetokounmpo Global Sustainable Equities ETF (the "Fund"). CGAM is jointly owned by Calamos Advisors LLC and Original C Fund, LLC ("Original C"), an entity whose voting rights are wholly owned by Original PE, LLC which, in turn, is wholly owned by Giannis Sina Ugo Antetokounmpo.

• Mr. Antetokounmpo serves on the Adviser's Board of Directors and has indirect control of half of the Adviser's Board.

• Mr. Antetokounmpo is not a portfolio manager of the Fund and is not involved in the day-to-day management of the Fund's investments, and neither Original C nor Mr. Antetokounmpo shall provide any "investment advice" to the Fund. Mr. Antetokounmpo provided input in selecting the initial strategy for the Fund.

• Mr. Antetokounmpo is involved with marketing efforts on behalf of the Adviser.

• If Mr. Antetokounmpo is no longer involved with the Fund or the Adviser then "Antetokounmpo" will be removed from the name of the Fund and the Adviser. Further, shareholders would be notified of any change in the name of the Fund or its strategy.

------

**Table of Contents**

---

| | |
|:---|:---|
| [Calamos Antetokounmpo Global <br>Sustainable Equities ETF](#CalamosAntetokounmpoGlobalSustainableEquitiesETF-2) | 1 |
| [Other Important Information <br>Regarding Fund Shares](#OtherImportantInformationRegardingFundShares-2) | 8 |
| [Additional Information About <br>Investment Strategies and Related <br>Risks](#AdditionalInformationAboutInvestmentStrategiesandRelatedRisks-2) | 9 |
| [Fund Facts](#FundFacts-2) | 16 |
| [Who Manages the Fund?](#WhoManagestheFund-2) | 16 |
| [How to Buy and Sell Shares](#HowtoBuyandSellShares-2) | 17 |
| [Dividends, Other Distributions and <br>Taxes](#DividendsOtherDistributionsandTaxes-2) | 19 |
| [Net Asset Value](#NetAssetValue-2) | 22 |
| [Fund Service Providers](#FundServiceProviders-2) | 23 |
| [Premium/Discount Information](#PremiumDiscountInformation-2) | 23 |
| [Investments by Other Investment <br>Companies](#InvestmentsbyOtherInvestmentCompanies-2) | 23 |
| [Financial Highlights](#FinancialHighlights-2) | 25 |
| [Other Information](#OtherInformation-2) | 26 |

---

------

Calamos Antetokounmpo Global Sustainable Equities ETF

Investment Objective

Calamos Antetokounmpo Global Sustainable Equities ETF (the "Fund") seeks long-term capital appreciation.

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):** | **Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments):** |
| Management Fees | 0.95% |
| Distribution and/or Service Fees (12b-1) | 0.00% |
| Other Expenses | 0.00% |
| Total Annual Fund Operating Expenses | 0.95% |

---

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 or do not 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:

You would pay the following expenses whether you sell or hold your Fund Shares at the end of the period:

---

| | | | |
|:---|:---|:---|:---|
| **One Year** | **Three Years** | **Five Years** | **Ten Years** |
| $97 | $303 | $525 | $1166 |

---

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. During the most recent fiscal year, the Fund's portfolio turnover rate was 15% of the average value of its portfolio.

Principal Investment Strategies

The Fund is an actively managed exchange-traded fund ("ETF") that does not seek to replicate the performance of a specified index. The Fund will, under normal circumstances, invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of companies in developed markets (including the U.S.) and emerging markets (including frontier market countries) that, in the view of Calamos Advisors LLC's ("Calamos Advisors") investment team (the "Team"), have above average growth potential and meet the sustainable investment criteria set out below. Under normal market conditions, the Fund will invest at least 40% of its net assets in non-U.S. equity securities, including emerging markets, unless market conditions are not deemed favorable by the Sub-adviser, in which case the Fund will invest at least 30% of its net assets in non-U.S. equity securities. The Fund generally invests in a minimum of five (5) countries.

Emerging markets are markets of countries in the initial stages of industrialization and generally have low per capita income. Foreign (non-U.S.) companies are those that either maintain their principal place of business outside of the United States, have their securities principally traded on non-U.S. exchanges or were formed under the laws of non-U.S. countries. Foreign companies may include companies doing business in the United States but meet the general criteria of a foreign company described above. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets are the least

PROSPECTUS \| November 28, 2025<br>1

------

Calamos Antetokounmpo Global Sustainable Equities ETF

advanced capital markets in the developing world. Frontier markets are countries with investable stock markets that are less established than those in the emerging markets. To determine if a country is an emerging market or frontier market country, the Team will use the classification provided by MSCI, Inc, a global investment research firm that provides stock indexes and portfolio risk and performance analytics. Foreign securities include American Depositary Receipts ("ADRs") or securities guaranteed by a U.S. person but which represent underlying shares of foreign issuers, and may include foreign securities in the form of European Depositary Receipts ("EDRs"), Global Depositary Receipts ("GDRs") or other securities representing underlying shares of foreign issuers.

The Team employs an integrated, fundamental, and proprietary sustainable investment research process to evaluate and select what the Team deems are high-quality growth opportunities. The Team believes a portfolio of equities issued by high-quality growth companies characterized by a history of producing consistent returns above the cost of capital with sustainable competitive advantages is the best way to achieve steady, strong, enduring relative returns. The Team believes that companies with strong sustainability characteristics (as further described below) are better equipped to adapt to change, to evolve, and to avoid unnecessary liabilities (which could include, for example, litigation costs), which means that investment in such companies has the potential to contribute to investor return and risk reduction. The Team believes that integrating this sustainability analysis alongside traditional financial analysis produces better financial and societal results.

The Team utilizes a proprietary sustainable investment research process, considering both quantitative and qualitative sustainability factors, to identify responsible, engaged companies (companies that demonstrate awareness and action surrounding the material environmental, social and governance issues facing their businesses and industries). The Team believes that a company's understanding of these principles demonstrates the qualities of innovation and leadership that create a distinct competitive advantage and build long-term value for a company. The Team considers a company's position on various factors such as ecological limits, environmental stewardship, environmental strategies, stance on human rights and equality, societal impact as well as its corporate governance practices. The Team conducts fundamental research to find companies with attractive financial and sustainability attributes. In conducting fundamental research, the Team combines traditional investment information with its proprietary three-tiered investment research process to identify companies which it believes represent leaders in sustainable business practices.

The Team believes that this creates a complete picture of how each company behaves commercially and how it deals with existing and emerging sustainability risks and opportunities. The three-tiered sustainable investment research process consists of: 1) exclusionary screens; 2) materiality assessments and 3) environmental and social impact scoring, each of which is described in turn below.

1. Exclusionary Screens: This process results in identifying certain industries and business activities that, in the Team's belief, are too environmentally risky or present social outcomes that are too unattractive to warrant investment consideration, which are thus avoided by the Team. The Team will generally exclude an issuer from investment consideration where the issuer derives revenue or profits that exceed 5% from one or more of the below-listed industries/business activities, namely:

• agricultural biotechnology,

• alcohol,

• animal testing\*,

• fossil fuels,

• gambling,

• metals & mining,

• nuclear energy,

• tobacco, and

• weapons.

\* A company's activities involving animal testing are considered on a case-by-case basis depending on purpose and methods.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>2

------

Calamos Antetokounmpo Global Sustainable Equities ETF

2. Materiality Assessment: The Team then applies third-party materiality mapping tools combined with its own insights and emphasis on environmental and social leadership to develop materiality theses, which enable the Team to identify and analyze the key ESG risks/opportunities for a particular industry.

3. Environmental and Social Scoring: Overlaying these top-down and bottom-up approaches, the Team then utilizes a proprietary sustainable investment scoring system, which considers both quantitative and qualitative factors, to identify investments for the Fund. The scoring system also considers a company's position in respect of various environmental and social characteristics, including: product contribution to a sustainable economy; product lifecycle innovation; operational efficiencies; inclusive finance; ensuring health and providing basic services; as well as a company's corporate governance practices. These qualitative metrics are considered alongside quantitative factors produced by research, and together, a score is determined, applied, and monitored going forward. The abovementioned score is just one part of the process. While required as a minimum, a "good" environmental and/or social score, one higher than 3 (out of 5), does not automatically mean that the Fund will invest in an investee company.

The Team utilizes a range of data sources as part of its proprietary sustainability ratings system. These data sources may include: corporate disclosures, third party research providers (e.g., ISS ESG, MSCI ESG, Bloomberg, etc.), non-governmental organizations ("NGOs") and non-profits (e.g., Greenpeace, Friends of Earth, etc.), academic publications, news services and memberships. While the Team may utilize the underlying data which supports a third party's ESG rating of an issuer, the Team does not rely on any ESG ratings of third-party research providers. The Team employs its proprietary sustainability ratings system for both initial company recommendations and ongoing monitoring of investments.

The Team may sell an investment in cases of valuation adjustments, availability of more attractive alternatives, or breakdowns in financial fundamentals or sustainability performance.

The Fund is classified as "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 of long-term capital appreciation 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 order of importance, with the most significant risks appearing first. 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:

• 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.

• 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.

• Key-Person Dependence Risk — The Adviser is jointly owned and controlled by Calamos Advisors LLC and, indirectly, by Giannis Sina Ugo Antetokounmpo, a well-known professional athlete. Unanticipated events, including, without limitation, death, adverse reputational events or business disputes, could result in Mr. Antetokounmpo no longer being associated or involved with the Adviser. Any such event could adversely impact the Fund and result in shareholders experiencing substantial losses.

• Large-Capitalization Investing Risk — Large-capitalization stocks as a group could fall out of favor with the market, which may cause the Fund to underperform funds that focus on other types of stocks.

PROSPECTUS \| November 28, 2025<br>3

------

Calamos Antetokounmpo Global Sustainable Equities ETF

• American Depositary Receipts Risk — The stocks of most foreign companies that trade in the U.S. markets are traded as ADRs. U.S. depositary banks issue these stocks. Each ADR represents one or more shares of foreign stock or a fraction of a share. The price of an ADR corresponds to the price of the foreign stock in its home market, adjusted to the ratio of the ADRs to foreign company shares. Therefore, while purchasing a security on a U.S. exchange, the risks inherently associated with foreign investing still apply to ADRs.

• 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.

• 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.

• 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 prices of small and mid-sized company stocks tend to be more volatile than prices of large company stocks.

• Sustainability (ESG) Policy Risk — The Fund's sustainability policy or integration procedures could cause it to perform differently compared to similar funds that do not have such a policy. The application of the sustainability standards of Calamos Advisors may affect the Fund's exposure to certain issuers, industries, sectors, and factors that may impact the relative financial performance of the Fund — positively or negatively — depending on whether such investments are in or out of favor. In executing the Fund's investment strategy Calamos Advisors has developed a proprietary sustainability rating system that relies in part on data provided by third parties. There is no assurance that third-party sustainability data sources will always be available or that such data will be accurate.

• 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.

• Emerging Markets Risk — Emerging market countries may have relatively unstable governments and economies based on only a few industries, which may cause greater instability. The value of emerging market securities will likely be particularly sensitive to changes in the economies of such countries. These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could hurt their economies and securities markets. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets, the least advanced capital markets in the developing world, are among the riskiest markets in the world in which to invest. Investments in this sector are typically illiquid, nontransparent and subject to very low regulation levels as well as high transaction fees, and may also have substantial political and currency risk.

• 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.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>4

------

Calamos Antetokounmpo Global Sustainable Equities ETF

• 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.

• 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.

• Currency Risk — To the extent that the Fund invests in securities or other instruments denominated in or indexed to foreign currencies, changes in currency exchange rates bring an added dimension of risk. Currency fluctuations could negatively impact investment gains or add to investment losses. Although the Fund may attempt to hedge against currency risk, the hedging instruments may not always perform as the Fund expects and could produce losses. Suitable hedging instruments may not be available for currencies of emerging market countries. Calamos Advisors may determine not to hedge currency risks, even if suitable instruments appear to be available.

• 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.

• 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.

• 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.

• 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.

• 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.

PROSPECTUS \| November 28, 2025<br>5

------

Calamos Antetokounmpo Global Sustainable Equities ETF

• Tax Risk — The Fund has elected and intends to qualify each year to be treated as a regulated investment company (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.

Fund Performance

**The following bar chart** and **table** indicate the risks of investing in the Fund by showing changes in the Fund's performance from calendar year to calendar year and how the Fund's average annual total returns compare with those of a broad measure of market performance. All returns include the reinvestment of dividends and distributions. As always, please note that the Fund's past performance (before and after taxes) cannot predict how it will perform in the future. Updated performance information is available at no cost by visiting www.calamos.com or by calling (866) 363-9219.

**ANNUAL TOTAL RETURN FOR YEARS ENDED 12.31**

![](j25294262_ba003.jpg)

---

| | | | |
|:---|:---|:---|:---|
| Highest Quarterly Return: | 5.83% (9/30/24) | Lowest Quarterly Return: | -4.48% (12/31/24) |

---

Average Annual Total Returns as of 12.31.24

The following table shows how the Fund's average annual performance (before and after taxes) for the one-year period ended December 31, 2024 and since the Fund's inception date of February 3, 2023 compared with broad measures of market performance. "Since Inception" returns shown for each index are returns since the inception of the Fund, or since the nearest subsequent month end when comparative index data is available only for full monthly periods. The after-tax returns show the impact of assumed federal income taxes on an investment in the Fund. "Return after taxes on distributions" shows the effect of taxable distributions, but assumes that you still hold the Fund shares at the end of the period and so do not have any taxable gain or loss on your investment. "Return after taxes on distributions and sale of Fund shares" shows the effect of taxable distributions and any taxable gain or loss that would be realized if the Fund shares were purchased at the beginning and sold at the end of the specified period.

The after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. Return after taxes on distributions and sale of Fund shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss on the sale of Fund shares.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>6

------

Calamos Antetokounmpo Global Sustainable Equities ETF

---

| | | | | |
|:---|:---|:---|:---|:---|
| **AVERAGE ANNUAL TOTAL RETURNS — FOR PERIODS ENDED 12.31.24** | **AVERAGE ANNUAL TOTAL RETURNS — FOR PERIODS ENDED 12.31.24** | **AVERAGE ANNUAL TOTAL RETURNS — FOR PERIODS ENDED 12.31.24** | **AVERAGE ANNUAL TOTAL RETURNS — FOR PERIODS ENDED 12.31.24** | **AVERAGE ANNUAL TOTAL RETURNS — FOR PERIODS ENDED 12.31.24** |
|  | **ONE YEAR** | **FIVE YEAR** | **TEN YEAR** | **SINCE<br>INCEPTION<br>(2/3/23)** |
| **Calamos Antetokounmpo Global Sustainable Equities ETF** | | | |  |
| *Returns Before Taxes* | 9.65% |  |  | 8.90% |
| *Returns After Taxes on Distributions* | 9.47% |  |  | 8.68% |
| *Returns After Taxes on Distributions and Sale of Fund Shares* | 5.84% |  |  | 6.83% |
| **MSCI ACWI Index\*** | 18.02% |  |  | 15.80% |
| **MSCI ACWI Index (Net)\*** | 17.49% |  |  | 15.24% |

---

\* The Fund's investment adviser added the broad-based securities market index in accordance with recent changes to regulatory disclosure requirements. The Fund continues to use the MSCI ACWI Index (Net) as an additional benchmark. The MSCI ACWI Index (Net) is a free float-adjusted market-capitalization-weighted index that is designed to measure the equity market performance of developed markets and emerging markets. Net return basis accounts for the impact of taxes and other costs associated with holding the constituent securities in the index.

Investment Adviser

Calamos Antetokounmpo Asset Management LLC, doing business as CGAM ("CGAM" or the "Adviser")

Subadviser

Calamos Advisors LLC

Portfolio Managers

---

| | | |
|:---|:---|:---|
| **PORTFOLIO MANAGER/<br>FUND TITLE (IF APPLICABLE)** | **PORTFOLIO MANAGER<br>EXPERIENCE IN THE FUND** | **PRIMARY TITLE<br>WITH SUB-ADVISER** |
| James Madden | Since February 2023 | SVP, Co-Portfolio Manager |
| Anthony Tursich | Since February 2023 | SVP, Co-Portfolio Manager |
| Beth Williamson | Since February 2023 | VP, Associate Portfolio Manager |

---

PROSPECTUS \| November 28, 2025<br>7

------

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

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 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.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>8

------

Additional Information About Investment Strategies <br>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 long-term capital appreciation.

The Fund is an actively managed exchange-traded fund ("ETF") that does not seek to replicate the performance of a specified index. The Fund will, under normal circumstances, invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of companies in developed markets (including the U.S.) and emerging markets (including frontier market countries) that, in the view of Calamos Advisors LLC's ("Calamos Advisors") investment team (the "Team"), have above average growth potential and meet the sustainable investment criteria set out below. Under normal market conditions, the Fund will invest at least 40% of its net assets in non-U.S. equity securities, including emerging markets, unless market conditions are not deemed favorable by the Sub-adviser, in which case the Fund will invest at least 30% of its net assets in non-U.S. equity securities. The Fund generally invests in a minimum of five (5) countries.

Emerging markets are markets of countries in the initial stages of industrialization and generally have low per capita income. Foreign (non-U.S.) companies are those that either maintain their principal place of business outside of the United States, have their securities principally traded on non-U.S. exchanges or were formed under the laws of non-U.S. countries. Foreign companies may include companies doing business in the United States but meet the general criteria of a foreign company described above. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets are the least advanced capital markets in the developing world. Frontier markets are countries with investable stock markets that are less established than those in the emerging markets. To determine if a country is an emerging market or frontier market country, the Team will use the classification provided by MSCI, Inc, a global investment research firm that provides stock indexes and portfolio risk and performance analytics. Foreign securities include American Depositary Receipts ("ADRs") or securities guaranteed by a U.S. person but which represent underlying shares of foreign issuers, and may include foreign securities in the form of European Depositary Receipts ("EDRs"), Global Depositary Receipts ("GDRs") or other securities representing underlying shares of foreign issuers.

The Team employs an integrated, fundamental, and proprietary sustainable investment research process to evaluate and select what the Team deems are high-quality growth opportunities. The Team believes a portfolio of equities issued by high-quality growth companies characterized by a history of producing consistent returns above the cost of capital with sustainable competitive advantages is the best way to achieve steady, strong, enduring relative returns. The Team believes that companies with strong sustainability characteristics (as further described below) are better equipped to adapt to change, to evolve, and to avoid unnecessary liabilities (which could include, for example, litigation costs), which means that investment in such companies has the potential to contribute to investor return and risk reduction. The Team believes that integrating this sustainability analysis alongside traditional financial analysis produces better financial and societal results.

The Team utilizes a proprietary sustainable investment research process, considering both quantitative and qualitative sustainability factors, to identify responsible, engaged companies (companies that demonstrate awareness and action surrounding the material environmental, social and governance issues facing their businesses and industries). The Team believes that a company's understanding of these principles demonstrates the qualities of innovation and leadership that create a distinct competitive advantage and build long-term value for a company. The Team considers a company's position on various factors such as ecological limits, environmental stewardship, environmental strategies, stance on human rights and equality, societal impact as well as its corporate governance practices. The Team conducts fundamental research to find companies with attractive financial and sustainability attributes. In conducting fundamental research, the Team combines traditional investment information with its proprietary three-tiered investment research process to identify companies which it believes represent leaders in sustainable business practices.

PROSPECTUS \| November 28, 2025<br>9

------

Additional Information About Investment Strategies and Related Risks

The Team believes that this creates a complete picture of how each company behaves commercially and how it deals with existing and emerging sustainability risks and opportunities. The three-tiered sustainable investment research process consists of: 1) exclusionary screens; 2) materiality assessments and 3) environmental and social impact scoring, each of which is described in turn below.

1. Exclusionary Screens: This process results in identifying certain industries and business activities that, in the Team's belief, are too environmentally risky or present social outcomes that are too unattractive to warrant investment consideration, which are thus avoided by the Team. The Team will generally exclude an issuer from investment consideration where the issuer derives revenue or profits that exceed 5% from one or more of the below-listed industries/business activities, namely:

• agricultural biotechnology,

• alcohol,

• animal testing\*,

• fossil fuels,

• gambling,

• metals & mining,

• nuclear energy,

• tobacco, and

• weapons.

2. Materiality Assessment: The Team then applies third-party materiality mapping tools combined with its own insights and emphasis on environmental and social leadership to develop materiality theses, which enable the Team to identify and analyze the key ESG risks/opportunities for a particular industry.

3. Environmental and Social Scoring: Overlaying these top-down and bottom-up approaches, the Team then utilizes a proprietary sustainable investment scoring system, which considers both quantitative and qualitative factors, to identify investments for the Fund. The scoring system also considers a company's position in respect of various environmental and social characteristics, including: product contribution to a sustainable economy; product lifecycle innovation; operational efficiencies; inclusive finance; ensuring health and providing basic services; as well as a company's corporate governance practices. These qualitative metrics are considered alongside quantitative factors produced by research, and together, a score is determined, applied, and monitored going forward. The abovementioned score is just one part of the process. While required as a minimum, a "good" environmental and/or social score, one higher than 3 (out of 5), does not automatically mean that the Fund will invest in an investee company.

The Team utilizes a range of data sources as part of its proprietary sustainability ratings system. These data sources may include: corporate disclosures, third party research providers (e.g., ISS ESG, MSCI ESG, Bloomberg, etc.), non-governmental organizations ("NGOs") and non-profits (e.g., Greenpeace, Friends of Earth, etc.), academic publications, news services and memberships. While the Team may utilize the underlying data which supports a third party's ESG rating of an issuer, the Team does not rely on any ESG ratings of third-party research providers. The Team employs its proprietary sustainability ratings system for both initial company recommendations and ongoing monitoring of investments.

The Team may sell an investment in cases of valuation adjustments, availability of more attractive alternatives, or breakdowns in financial fundamentals or sustainability performance.

The Fund is classified as "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 its net assets (plus borrowings for investment purposes, if any) in equity securities of companies in developed markets (including the U.S.) and emerging markets (including frontier market countries) that, in the view of Calamos Advisors LLC's

\* A company's activities involving animal testing are considered on a case-by-case basis depending on purpose and methods.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>10

------

Additional Information About Investment Strategies and Related Risks

investment team, have above average growth potential and meet the sustainable investment criteria set out herein. Although this requirement may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders in writing at least 60 days prior to any change in its 80% policy.

Fund Investments

Principal Investments

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 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. 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.

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 or CGAM, Calamos

PROSPECTUS \| November 28, 2025<br>11

------

Additional Information About Investment Strategies and Related Risks

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.

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.

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.

Key-Person Dependence Risk. The Adviser is jointly owned and controlled by Calamos Advisors LLC and, indirectly, by Giannis Sina Ugo Antetokounmpo, a well-known professional athlete. Unanticipated events, including, without limitation, death, adverse reputational events or business disputes, could result in Mr. Antetokounmpo no longer being associated or involved with the Adviser. Any such event could adversely impact the Fund and result in shareholders experiencing substantial losses.

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 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.

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.

Recent Market Events. Since the 2008 financial crisis, 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 (such as wars, terror attacks, natural or environmental disasters, country instability, and public health emergencies), measures to address budget deficits, downgrading of sovereign debt, dramatic changes in currency exchange rates, and public sentiment.

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. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters, rapid technological developments, such as artificial intelligence, and other circumstances in one country or region could have profound impacts on global economies or markets. Widespread disease and virus epidemics and pandemics, 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.

American Depositary Receipts Risk. The stocks of most foreign companies that trade in the U.S. markets are traded as American Depositary Receipts (ADRs). U.S. depositary banks issue these stocks. Each ADR represents one or more shares of foreign stock or a fraction of a share. The price of an ADR corresponds to the price of the foreign stock in its home market, adjusted to the ratio of the ADRs to foreign company shares. Therefore, while purchasing a security on a U.S. exchange, the risks inherently associated with foreign investing still apply to ADRs.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>12

------

Additional Information About Investment Strategies and Related Risks

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.

Currency Risk. To the extent that a Fund invests in securities or other instruments denominated in or indexed to foreign currencies, changes in currency exchange rates bring an added dimension of risk. Currency fluctuations could negatively impact investment gains or add to investment losses. Although a Fund may attempt to hedge against currency risk, the hedging instruments may not always perform as the Fund expects and could produce losses. Suitable hedging instruments may not be available for currencies of emerging market countries. Calamos Advisors may determine not to hedge currency risks, even if suitable instruments appear to be available.

Emerging Markets Risk. Investment in foreign securities may include investment in securities of foreign issuers located in less developed countries, which are sometimes referred to as emerging markets. Emerging market countries may have relatively unstable governments and economies based on only a few industries, which may cause greater instability. The value of emerging market securities will likely be particularly sensitive to changes in the economies of such countries (such as reversals of economic liberalization, political unrest or changes in trading status). These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could hurt their economies and securities markets. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets, the least advanced capital markets in the developing world, are among the riskiest markets in the world in which to invest. Frontier markets have the fewest number of investors and investment holdings and may not even have stock markets on which to trade. Investments in this sector are typically illiquid, nontransparent and subject to very low regulation levels as well as high transaction fees, and may also have substantial political and currency risk. Emerging and frontier markets both offer the prospect of higher returns with higher risk. However, emerging markets are more stable and developed than frontier markets. The economies of emerging market countries have achieved a rudimentary level of development, while frontier markets represent the least economically developed nations in the global marketplace. Emerging and frontier markets also carry several types of investment risk, including market, political and currency risk, as well as the risk of nationalization.

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.

Sustainability (ESG) Policy Risk. The Fund's sustainability policy or integration procedures could cause it to perform differently compared to similar funds that do not have such a policy. The application of the sustainability standards of Calamos Advisors may affect the Fund's exposure to certain issuers, industries, sectors, and factors that may impact the relative financial performance of the Fund — positively or negatively — depending on whether such investments are in or out of favor. In executing the Fund's investment strategy Calamos Advisors has developed a proprietary sustainability rating system that relies in part on data provided by third parties. There is no assurance that third-party sustainability data sources will always be available or that such data will be accurate.

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

PROSPECTUS \| November 28, 2025<br>13

------

Additional Information About Investment Strategies and Related Risks

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.

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.

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.

Large-Capitalization Investing Risk. Large-capitalization stocks as a group could fall out of favor with the market, which may cause the 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.

Mid-Sized Company Risk. 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.

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.

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.

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

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>14

------

Additional Information About Investment Strategies and Related Risks

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.

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.

Small Company Risk. Small company stocks have historically been subject to greater investment risk than mid-sized and large company stocks. The risks generally associated with small 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 small company stocks tend to be more volatile than prices of mid-sized and 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.

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 SAI and on the Fund's website, www.calamos.com.

PROSPECTUS \| November 28, 2025 <br>15

------

Fund Facts

Who manages the Fund?

Investment Adviser

Calamos Antetokounmpo Asset Management LLC, doing business as CGAM ("CGAM"), an investment adviser registered with the SEC under the Investment Advisers Act of 1940, serves as the Fund's adviser ("Adviser"). CGAM is jointly owned by Calamos Advisors LLC and Original C Fund, LLC, an entity whose voting rights are wholly owned by Original PE, LLC which, in turn, is wholly owned by Giannis Sina Ugo Antetokounmpo.

Subject to the overall authority of the Board of Trustees, CGAM provides continuous investment supervision and management to the Fund under a management agreement. For these services, the Fund pays CGAM 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 Antetokounmpo Global Sustainable Equities ETF | 0.95% |

---

Out of this management fee, CGAM 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 June 24, 2025, the board of trustees unanimously approved the renewal of the investment advisory agreement and sub-advisory agreement for the Fund. A discussion regarding the basis for the approval by the board of trustees of the management agreement for the Fund is included in the Fund's Form N-CSR for the fiscal year ended July 31, 2025.

Subadviser

The Fund is subadvised by Calamos Advisors LLC ("Calamos Advisors" or the "Subadviser"), 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 December 31, 2024, were $40 billion ($38 billion of which represented Calamos Advisors' assets under management). Calamos Asset Management, Inc. ("CAM") is the sole manager of CILLC. As of July 31, 2025, approximately 22.4% of the outstanding interests of CILLC was owned by CAM, 77.72% by Calamos Partners LLC ("CPL"), and 0.04% by Calamos Equity Partners LLC ("CEP"). CAM is owned by John P. Calamos, Sr. and John S. Koudounis. CPL is owned by Calamos Family Partners, Inc. ("CFP") and John S. Koudounis. CFP is beneficially owned by members of the Calamos family, including John P. Calamos, Sr. CEP is owned by John S. Koudounis and Daniel L. Dufresne.

Calamos Advisors has full investment discretion and makes all determinations with respect to the investment of the Fund's assets, subject to the general supervision of the Adviser and the Board of Trustees. Calamos Advisors also furnishes office space, equipment and management personnel to the Calamos ETF Trust (the "Trust").

Pursuant to an investment sub-advisory agreement between CGAM, Calamos Advisors and the Trust, on behalf of the Fund (the "Investment Sub-Advisory Agreement"), CGAM has agreed to pay a monthly sub-advisory fee at an annual rate to Calamos Advisors in an amount based on the Fund's average daily net assets. CGAM is responsible for paying the entirety of Calamos Advisors' sub-advisory fee. The Fund does not directly pay Calamos Advisors.

Portfolio Managers

James Madden. James Madden joined Calamos Advisors on August 24, 2021 as a Senior Vice President and Co-Portfolio Manager. Previously, he was Portfolio Manager at Trillium Asset Management, LLC. Prior to that, he was Chief Investment Officer and Senior Portfolio Manager at Portfolio 21.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>16

------

Fund Facts

Anthony Tursich. Anthony Tursich joined Calamos Advisors on August 24, 2021 as a Senior Vice President and Co-Portfolio Manager. Previously, he was Chief Investment Officer and Portfolio Manager at Pearl Impact Capital, LLC since 2018. Prior to that, Mr. Tursich was a Partner, Senior Portfolio Manager and member of the Executive Committee at Portfolio 21.

Beth Williamson. Beth Williamson joined Calamos Advisors on November 3, 2021. She serves as Vice President, Head of Sustainable Equities Research and Associate Portfolio Manager. Previously, she was Director of ESG Research and Trillium Asset Management, LLC. Prior to that, she was a Senior Sustainability Analyst and member of the Executive Committee at Portfolio 21.

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

James Madden and Anthony Tursich, Co-Portfolio Managers, and Beth Williamson, Associate Portfolio Manager are the Fund's portfolio managers. The portfolio managers have responsibility for allocating the portfolio across the market capitalization spectrum, sectors, and geographies within the portfolio's eligible investment universe and for reviewing the overall composition of the portfolio to ensure compliance with its stated investment objective. The portfolio managers, in collaboration with other members of the Calamos Advisors investment teams, have the responsibility of overseeing the integration of the Fund's sustainable investment approach and framework to ensure compliance with the Fund's stated investment approach.

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange under the symbol SROI 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 National Independence Day, 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.

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

PROSPECTUS \| November 28, 2025<br>17

------

Fund Facts

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").

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, 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.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>18

------

Fund Facts

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, 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 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 Fund Shares 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.

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).

PROSPECTUS \| November 28, 2025<br>19

------

Fund Facts

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.

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. 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.

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.

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 and such Authorized Participant's aggregate basis in the securities surrendered plus (or minus) any cash paid (or received). A person who redeems Creation Units for equity securities will generally recognize a gain or loss equal to the difference between such person's basis in the Creation Units and the aggregate market value of the securities received plus (or minus) any cash received (or paid). 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. In addition, when a regulated investment company redeems a shareholder in

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>20

------

Fund Facts

kind, the regulated investment company generally is not required to recognize taxable gains in respect of the portfolio securities it distributes to the redeeming shareholder. However, the Fund may be required to recognize taxable gain on the distribution of certain securities, and the Internal Revenue Service may assert that the Fund must recognize taxable gain in respect of certain other securities that the Fund distributes to a shareholder in exchange for Creation Units, which may increase the amount of taxable gains that the Fund would otherwise be required to distribute in order to maintain its qualification as a regulated investment company and avoid a Fund-level tax.

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.

Authorized Participants that are dealers may be subject to special tax rules and should consult their own tax advisors regarding the tax consequences of purchasing and redeeming Creation Units in their capacity as dealers.

Treatment of Fund Expenses

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

Non-U.S. Tax Credit

Because the Fund may invest in non-U.S. securities, the tax statement that you receive may include an item showing non-U.S. taxes the Fund paid to other countries. In this case, dividends taxed to you will include your share of the taxes the Fund paid to other countries. You may be able to deduct or receive a tax credit for your share of these taxes.

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. This withholding tax is also currently scheduled to apply to the gross proceeds from the disposition of securities that produce U.S. source interest or dividends. However, proposed regulations may eliminate the requirement to withhold on payments of gross proceeds from dispositions.

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. In this case, the Fund 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

PROSPECTUS \| November 28, 2025<br>21

------

Fund Facts

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. 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, administration, and distribution 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, 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 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 CGAM 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

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>22

------

Fund Facts

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, MA 02114-2016, serves as the Fund's administrator, custodian, fund accounting and transfer agent.

Calamos Financial Services LLC ("CFS"), located at 2020 Calamos Court, Naperville, Illinois 60563, 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.

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.

PROSPECTUS \| November 28, 2025<br>23

------

This page intentionally left blank.

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>24

------

Financial Highlights

The financial highlights table is intended to help you understand the Fund's financial performance for the period of February 3, 2023 through July 31, 2025. Certain information reflects financial results for a single Fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all dividends and distributions). This information has been audited by Deloitte & Touche LLP, whose report, along with the Fund's financial statements, are included in the SAI, which is available upon request.

**FINANCIAL HIGHLIGHTS**

**Selected data for a share outstanding throughout each year were as follows:**

---

| | | | |
|:---|:---|:---|:---|
|  | Year Ended<br>July 31, | Year Ended<br>July 31, | February 3, 2023• Through<br>July 31, |
|  | **2025** | **2024** | **2023** |
| Per share operating performance | Per share operating performance | Per share operating performance | Per share operating performance |
| Net asset value, beginning of year | $29.17 | $26.59 | $25.00 |
| Income from investment operations: | Income from investment operations: | Income from investment operations: | Income from investment operations: |
| Net investment income (loss)(a) | 0.20 | 0.27 | 0.18 |
| Net realized and unrealized gain (loss) | 2.46 | 2.56 | 1.41 |
| Total from investment operations | 2.66 | 2.83 | 1.59 |
| Less distributions to common shareholders from: | Less distributions to common shareholders from: | Less distributions to common shareholders from: | Less distributions to common shareholders from: |
| Net investment income | (0.20) | (0.25) |  |
| Total distributions(b) | (0.20) | (0.25) |  |
| Net asset value, end of year | $31.63 | $29.17 | $26.59 |
| Total return applicable to common shareholders | Total return applicable to common shareholders | Total return applicable to common shareholders | Total return applicable to common shareholders |
| Total investment return based on: | Total investment return based on: | Total investment return based on: | Total investment return based on: |
| Net asset value(c) | 9.13% | 10.74% | 6.36% |
| Ratios to average net assets applicable to common shareholders | Ratios to average net assets applicable to common shareholders | Ratios to average net assets applicable to common shareholders | Ratios to average net assets applicable to common shareholders |
| Net expenses | 0.95% | 0.95% | 0.95<br> %(d) |
| Net investment income (loss) | 0.67% | 1.02% | 1.47<br> %(d) |
| Supplemental data | Supplemental data | Supplemental data | Supplemental data |
| Net assets applicable to common shareholders, end of year (000) | $15939 | $11784 | $10743 |
| Portfolio turnover rate(e)(f) | 15% | 25% | 7% |

---

&nbsp;&nbsp;&nbsp;&nbsp;• Commencement of operations.

&nbsp;&nbsp;&nbsp;&nbsp;(a) Net investment income (loss) allocated based on average shares method.

&nbsp;&nbsp;&nbsp;&nbsp;(b) Distribution for annual periods determined in accordance with federal income tax regulations.

&nbsp;&nbsp;&nbsp;&nbsp;(c) Total return measures net investment income and capital gain or loss from portfolio investments assuming reinvestment of dividends and capital gains distributions. Total return is not annualized for periods that are less than a full year and does not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

&nbsp;&nbsp;&nbsp;&nbsp;(d) Annualized.

&nbsp;&nbsp;&nbsp;&nbsp;(e) Portfolio turnover rate excludes securities received or delivered from in-kind processing of creations or redemptions.

&nbsp;&nbsp;&nbsp;&nbsp;(f) Not annualized.

PROSPECTUS \| November 28, 2025<br>25

------

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

CALAMOS ANTETOKOUNMPO GLOBAL SUSTAINABLE EQUITIES ETF<br>26

------

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.

PROSPECTUS \| November 28, 2025<br>27

------

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 and in Form N-CSR. 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. In Form N-CSR, you will find the Fund's annual and semi-annual financial statements. 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, Sub-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 publicinfo@sec.gov.

![](j25294262_za004.jpg)

2020 Calamos Court

Naperville, IL 60563-2787

866.363.9219 www.calamos.com

SEC File #811-22887

SROISTAPRO 112825

------