The Fund is an actively managed exchange-traded fund ("ETF") that is designed to provide investors with the opportunity to benefit from increases in the Underlying ETF's share price up to the stated cap over a specified period of time of approximately one-year (the "Outcome Period"), while providing protection against decreases in the Underlying ETF's share price over the same Outcome Period (before taking fees and expenses into account).

Under normal market conditions, the Fund will invest substantially all of its assets in FLexible EXchange Options ("FLEX Options") that reference the price performance of the SPDR®​ S&P 500®​ ETF Trust (the "Underlying ETF"). FLEX Options are customized equity or index option contracts that trade on an exchange but provide investors with the ability to customize key contract terms like exercise prices, styles and expiration dates.

The Underlying ETF is an exchange-traded unit investment trust that uses a replication strategy, meaning it invests in as many of the stocks in the S&P 500®​ Index as is practicable. PDR Services, LLC ("PDR") serves as the Underlying ETF's sponsor. The investment objective of the Underlying ETF is to seek to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the S&P 500®​ Index. The Fund's performance will not reflect the payment of dividends by the Underlying ETF. See "The Underlying ETF" for more information.

The returns an investor will receive from an investment in the Fund have characteristics that are distinct from many other investment vehicles, including the Underlying ETF. It is important that you understand these characteristics before making an investment in the Fund.

The Fund uses FLEX Options to employ a capital protected target outcome strategy. Target outcome strategies seek to produce pre-determined investment outcomes based upon the performance of an underlying security or index. The pre-determined outcomes sought by the Fund, which include capital protection to absorb 100% of losses (before fees and expenses) in the Underlying ETF (the "Capital Protection") and upside participation to a stated cap (before fees and expenses) (the "Cap"), are based on the price performance of the Underlying ETF over an Outcome Period.

The outcomes the Fund seeks for investors that hold Fund Shares for an entire Outcome Period are as follows, though there can be no guarantee these results will be achieved:

•  If the Underlying ETF appreciates over the Outcome Period, the combination of FLEX Options held by the Fund seeks to provide upside participation matching that of the Underlying ETF, up to a cap that is determined at the start of the Outcome Period.

•  If the Underlying ETF decreases over the Outcome Period, the combination of FLEX Options held by the Fund seeks to provide protection against 100% of Underlying ETF losses, prior to taking into account the Fund's fees and expenses.

The Fund does not seek to provide capital protection against 100% of losses (before fees and expenses) of the Underlying ETF as of any time other than the end of the Outcome Period.

For the Outcome Period beginning on August 1, 2024 through July 31, 2025, the Cap is 8.74% and the Capital Protection is 100%. When the Fund's fees and expenses are taken into account, the Cap is 8.05% and the Capital Protection is 99.31%. The Cap and Capital Protection will be further reduced by any brokerage commissions, trading fees, taxes and extraordinary expenses not included in the Fund's management fee.

The current Outcome Period is from August 1, 2024 through July 31, 2025. The Fund will not terminate after the conclusion of the Outcome Period. After the conclusion of the Outcome Period, another will begin. On the first day of each new Outcome Period, the Fund resets by investing in a new set of FLEX Options that are designed to provide a new cap for the new Outcome Period. This means that the Cap will change for each Outcome Period based upon prevailing market conditions at the beginning of each Outcome Period. The capital protection will remain the same for each Outcome Period. The Capital Protection and Cap, and the Fund's value relative to each, should be considered before investing in the Fund. The Fund will be perpetually offered and not terminate after the current or any subsequent Outcome Period. Approximately one week prior to the end of an Outcome Period, the Fund's website will be updated to alert existing shareholders that the Outcome Period is approaching its conclusion and will disclose the anticipated Cap range for the next Outcome Period. See "Subsequent Outcome Periods" for more information.

Upon conclusion of the Outcome Period, the Fund will receive the cash value of all the FLEX Options it held for that Outcome Period. It will then invest in a new series of FLEX Options with an expiration date of approximately one year in the future, and a new Outcome Period will begin. Each FLEX Option's value is ultimately derived from the performance of the Underlying ETF's share price during that time. As the terms of the FLEX Options do not change during an Outcome Period, the outcomes, including the Cap and Capital Protection discussed below, will be measured to the Fund's net asset value ("NAV") on the first day of the Outcome Period.

The stated Cap and Capital Protection may only be realized by investors who continuously hold Fund Shares from the commencement of an Outcome Period until its conclusion. An investor who purchases Fund Shares other than on the first day of an Outcome Period and/or sells Fund Shares prior to the end of an Outcome Period may experience results that are very different from the target outcomes sought by the Fund for that Outcome Period. While the Cap and Capital Protection provide

the intended outcomes only for investors that hold their Fund Shares throughout the complete term of the Outcome Period, an investor can expect the value of their Fund Shares to generally move in the same direction as the Underlying ETF during the Outcome Period. If investors buy or sell on a date other than the start or end date of the Outcome Period, their returns will be different and they may incur losses in excess of the Capital Protection level (i.e., losses exceeding 0%) and they may not experience gains up to the Cap. See "Capital Protection and Cap" for more information.

The Fund's website, www.calamos.com, provides information relating to the possible outcomes for an investor of an investment in the Fund on a daily basis, if purchased on that date and held through the end of the Outcome Period, including the Fund's value relative to the Cap and Capital Protection. Before purchasing Fund Shares, an investor should visit the Fund's website to review this information and understand the possible outcomes of an investment in Fund Shares on a particular day and held through the end of the Outcome Period.

The Fund's investment objective is not a fundamental policy, and therefore may be changed by the Board without shareholder approval.

The Fund seeks to generate returns that match the Underlying ETF, up to the Cap (discussed in detail below), while limiting downside losses. The hypothetical illustrations provided below are designed to illustrate the outcomes that the Fund seeks to provide for investors who hold Fund Shares for the entirety of the Outcome Period. The hypothetical examples set forth below do not represent the performance of the Fund and investors should not rely on the hypothetical examples shown below as an indication of the actual or future performance of the Fund. There is no guarantee that the Fund will be successful in its attempt to provide the target outcomes for an Outcome Period. The returns that the Fund seeks to provide do not include the costs associated with purchasing Fund Shares and certain expenses incurred by the Fund. In the payoff profile illustration, the dotted line represents the Underlying ETF's performance, and the solid line represents the return profile gross of fees and expenses sought by the Fund in relation to the Underlying ETF's indicated performance. The bar chart below represents the Fund's hypothetical intended return profile based upon the performance of the Underlying ETF.

Explanation of diagram:

1. Calamos S&P 500 Structured Alt Protection ETF — August Participation Layer: The dotted grey line represents the first layer, which involves purchasing a near zero-strike (i.e., deep in-the-money) call on the reference asset, at a pre-determined strike to provide full participation to the price return of the underlying reference asset. In other words, the full price participation provided by this layer provides potential gains and losses that are tantamount to that of owning the underlying reference asset outright, except that this layer does not participate in the dividend yield of the underlying reference asset.

2. Capital Protection Layer: The solid grey line represents the second layer, which involves purchasing an at-the-money put option, which produces protection equal to 100% of losses (before fees and expenses) of the price return of the reference asset, over the Outcome Period.

3. Upside Participation Layer (the "Cap"): The solid black line illustrates the final layer, which involves selling an out-of-the-money call, thereby creating the upside cap. The strike price at which the call is sold is determined so that the combined net options purchase price is approximately equal to the underlying asset's current value. The cost of this layer is a credit equal to the price that would make the total package "no-cost" or fully financed.

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

Capital Protection and Cap

The Fund seeks to provide capital protection to absorb 100% of losses (before fees and expenses) of the Underlying ETF at the end of each Outcome Period. When the Fund's management fees are taken into account, the Capital Protection level is reduced to 99.31%. The Capital Protection level will be further reduced by any brokerage commissions, trading fees, taxes and extraordinary expenses not included in the Fund's management fee. If the Fund is required to increase its holdings of cash during the Outcome Period to pay fees and expenses incurred by the Fund, the Capital Protection level may be further reduced. The Fund does not seek to provide capital protection against 100% of losses (before fees and expenses) of the Underlying ETF as of any time other than the end of the Outcome Period.

During the Outcome Period, there may be periods of significant disparity between the Fund's NAV and the Underlying ETF's price performance. As the Underlying ETF price and the Fund's NAV change over the Outcome Period, an investor acquiring Fund Shares after the start of the Outcome Period will likely have a different return potential than an investor who purchased Fund Shares at the start of the Outcome Period. This is because while the Cap and Capital Protection for the Outcome Period

are fixed levels that are calculated in relation to the Underlying ETF price and the Fund's NAV at the start of an Outcome Period and remain constant throughout the Outcome Period, an investor purchasing Fund Shares at market value during the Outcome Period likely purchased Fund Shares at a price that is different from the Fund's NAV at the start of the Outcome Period (i.e., the NAV that the Cap and Capital Protection reference). For example, if an investor purchases Fund Shares during an Outcome Period at a time when the Fund has increased in value from the value of the Fund on the first day of the Outcome Period (the "Initial Fund Value"), that investor's Cap will essentially be decreased by the amount of the increase in the Underlying ETF's value, and the capital protection will not set in until the Fund's NAV returns to its Initial Fund Value (i.e., a shareholder must experience losses prior to gaining the protection offered by the Fund's Capital Protection because the Fund must first decrease in value to its Initial Fund Value for the Outcome Period before subsequent losses will be protected by the Capital Protection). Conversely, if an investor purchases Fund Shares during an Outcome Period at a time when the Underlying ETF has decreased in value, the Fund's NAV may dip below the Initial Fund Value. However, in this scenario, that investor's potential gain could be larger than the Fund's Cap for the Outcome Period because the investor may experience the full gain if the Fund recovers the value it has lost from the first day of the Outcome Period through the date the investor purchased its Fund Shares plus any additional gains between the Initial Fund Value and the Cap. There is no guarantee that the Fund will recover such value or experience such gains. The Cap and capital protection relative to the Initial Fund Value, however, will not change over the Outcome Period.

While the Fund seeks to provide 100% protection against losses experienced by the Underlying ETF (before fees and expenses) for shareholders who hold Fund Shares for an entire Outcome Period, there is no guarantee it will successfully do so. If the Fund's NAV has increased significantly, a shareholder that purchases Fund Shares after the first day of an Outcome Period could lose their entire investment. An investment in the Fund is only appropriate for shareholders willing to bear those losses. There is no guarantee the capital protection and cap will be successful and a shareholder investing at the beginning of an Outcome Period could also lose their entire investment.

The returns of the Fund are subject to a cap for each Outcome Period, calculated (before fees and expenses) at the beginning of each Outcome Period. Unlike other investment products, the potential returns an investor can receive from the Fund are subject to a pre-determined upside return Cap that represents the maximum percentage return an investor can achieve from an investment in the Fund for an entire Outcome Period. If the Underlying ETF experiences any percentage gains over the amount of the Cap, Fund shareholders will not experience those gains. Therefore, regardless of the price return of the Underlying ETF, the Cap (net of fees) is the maximum return an investor can achieve from an investment in the Fund for that Outcome Period. The Cap is set on the first day of each Outcome Period. The Cap is provided prior to taking into account annual Fund management fees of 0.69% of the Fund's daily net assets, brokerage commissions, trading fees, taxes and any extraordinary expenses (such as unexpected litigation) incurred by the Fund. The pre-determined Cap applicable to an Outcome Period will vary based on prevailing market conditions at the time that the Cap is set, including interest rate levels, Underlying ETF volatility, and the relationship of puts and calls on the FLEX Options.

The Cap level is a result of the design of the Fund's principal investment strategy. To provide the Capital Protected Target Outcome, the Fund purchases and sells a series of put and call FLEX Options on or around the last business day of the month prior to the beginning of an Outcome Period. As the purchaser of these FLEX Options, the Fund is obligated to pay a premium to the seller of those FLEX Options. The Adviser will calculate the amount of premiums that the Fund will owe on the put options acquired to provide the Capital Protection and will then sell call FLEX Options with terms that entitle the Fund to receive premiums such that the net amount of premiums paid per unit of the Underlying ETF is approximately equal to the price per unit of shares of the Underlying ETF. The Cap is the strike price of those FLEX Options the Fund is selling. The Cap, and the Fund's value relative to it on any given day, should be considered before investing in the Fund. If an investor purchases Fund Shares during an Outcome Period, and the Fund has already increased in value above its Initial Fund Value for that Outcome Period to a level near the Cap, an investor purchasing Fund Shares will have limited to no gain potential for the remainder of the Outcome Period (because the investor's potential gain will be limited to the difference between the Fund's NAV on the date the investor purchased the Fund Shares and the Cap). However, the investor will remain vulnerable to significant downside risk because the investor will bear the losses between the price at which it purchased its Fund Shares and the Initial Fund Value for the Outcome Period before subsequent losses will be protected by the Capital Protection. If an

investor buys Fund Shares when the price exceeds the Cap, an investor selling their shares at the end of the Outcome Period will not experience any gain regardless of the price return of the Underlying ETF.

There is no guarantee that the Fund will be successful in providing these investment outcomes for any Outcome Period, and an investor may experience returns on the Fund significantly below the Cap.

In periods of extreme market volatility or during market disruption events, the Fund's ability to offset investor losses through the use of the FLEX Options to achieve the stated Capital Protection, or provide a return up to the stated upside Cap may be impaired, resulting in an upside limit significantly below the Cap and downside protection significantly lower than full capital protection (i.e., losses greater than 0%), because the Fund may not be able to trade or exercise existing FLEX Options, or may not receive timely payment from its counterparties. An investor may lose their entire investment and an investment in the Fund is only appropriate for investors willing to bear those losses.

For each Outcome Period, the Fund will invest in both purchased and written put and call FLEX Options that reference the Underlying ETF. Because the value of the Fund is based on FLEX Options that reference the Underlying ETF and not the Underlying ETF directly, variations in the value of the FLEX Options impact the correlation between the Fund's NAV and the price of the Underlying ETF.

General Information about FLEX Options

FLEX Options are customizable exchange-traded option contracts guaranteed for settlement by the Options Clearing Corporation ("OCC"). The OCC guarantees performance by each of the counterparties to the FLEX Options, becoming the "buyer for every seller and the seller for every buyer," with the goal of protecting clearing members and options traders from counterparty risk. The OCC may make adjustments to FLEX Options for certain significant events, as more fully described in the Fund's Statement of Additional Information. Although guaranteed for settlement by the OCC, FLEX Options are still subject to counterparty risk with the OCC and subject to the risk that the OCC may fail to perform the settlement of the FLEX Options due to bankruptcy or other adverse reasons. The FLEX Options that the Fund will hold that reference the Underlying ETF will give the Fund the right or the obligation to either receive or deliver shares of the Underlying ETF, or the right or the obligation to either receive or deliver a cash payment on the option expiration date based upon the difference between the Underlying ETF's value and a strike price, depending on whether the option is a put or call option and whether the Fund purchases or sells the option. The FLEX Options held by the Fund are European style options, which are exercisable at the strike price only on the FLEX Option expiration date. The Fund will generally, under normal conditions, hold FLEX Options for each Outcome Period. The Fund will purchase call options (giving the Fund the right to receive shares of the Underlying ETF or a cash payment) and put options (giving the Fund the right to deliver shares of the Underlying ETF or a cash payment), while simultaneously selling (i.e., writing) call options (giving the Fund the obligation to deliver shares of the Underlying ETF or a cash payment). The Fund intends to structure the FLEX Options so that any amount owed by the Fund on the written FLEX Options will be covered by payouts at expiration from the purchased FLEX Options. As a result, the Fund expects the FLEX Options to be fully covered and no additional collateral will be necessary during the life of the Fund. The Fund receives premiums in exchange for the written FLEX Options and pays premiums in exchange for the purchased FLEX Options. The OCC and securities exchanges on which the FLEX Options are listed do not charge ongoing fees to writers or purchasers of the FLEX Options during their life for continuing to hold the option contracts but may charge transaction fees. Each of the FLEX Options purchased and sold throughout the Outcome Period will have the same terms, such as strike price and expiration date, as the FLEX Options purchased and sold on the first day of the Outcome Period. On the Flex Options expiration date, the Fund intends to sell the Flex Options prior to their expiration or cash-settle the Flex Options and use the resulting proceeds to purchase new Flex Options for the next Outcome Period.

The Underlying ETF

The Underlying ETF is an exchange-traded unit investment trust that uses a replication strategy, meaning it invests in as many of the stocks in the S&P 500®​ Index as is practicable. PDR Services, LLC ("PDR") serves as the Underlying ETF's sponsor. The investment objective of the Underlying ETF is to seek to provide investment results that, before fees and expenses, correspond generally to the price and yield performance of the S&P 500®​ Index (the "Index"). See below for a description of the Underlying ETF's principal investment strategies and risks. You can find the Underlying ETF's prospectus and other information

about the ETF, including the statement of additional information and most recent reports to shareholders, online at https://us.spdrs.com/en/etf/spdr-sp-500-etf-SPY.

The summary information below regarding the Underlying ETF comes from its filings with the SEC. You are urged to refer to the SEC filings made by the Underlying ETF and to other publicly available information (e.g., the ETF's annual reports) to obtain an understanding of the ETF's business and financial prospects. The following description of the Underlying ETF's principal investment strategies was taken directly from the Underlying ETF's prospectus, dated January 26, 2024 ("SPY" refers to the Underlying ETF; other defined terms have been modified).

"SPY seeks to achieve its investment objective by holding a portfolio of the common stocks that are included in the Index (the "Portfolio"), with the weight of each stock in SPY's Portfolio substantially corresponding to the weight of such stock in the Index. In SPY's prospectus, the term "Portfolio Securities" refers to the common stocks that are actually held by SPY and make up SPY's Portfolio, while the term "Index Securities" refers to the common stocks that are included in the Index, as determined by the index provider, S&P Dow Jones Indices LLC ("S&P"). At any time, SPY's Portfolio will consist of as many of the Index Securities as is practicable. To maintain the correspondence between the composition and weightings of Portfolio Securities and Index Securities, State Street Global Advisors Trust Company (the "Trustee") or its parent company, State Street Bank and Trust Company ("SSBT") adjusts SPY's Portfolio from time to time to conform to periodic changes made by S&P to the identity and/or relative weightings of Index Securities in the Index. SPY's Trustee or SSBT aggregates certain of these adjustments and makes changes to SPY's Portfolio at least monthly, or more frequently in the case of significant changes to the Index. SPY may pay transaction costs, such as brokerage commissions, when it buys and sells securities (or "turns over" its Portfolio). Such transaction costs may be higher if there are significant rebalancings of Index Securities in the Index, which may also result in higher taxes when SPY's units are held in a taxable account. These costs, which are not reflected in SPY's estimated annual Trust ordinary operating expenses, affect SPY's performance. During the most recent fiscal year, SPY's portfolio turnover rate was 2% of the average value of its portfolio. SPY's portfolio turnover rate does not include securities received or delivered from processing creations or redemptions of SPY's units. Portfolio turnover will be a function of changes to the Index as well as requirements of SPY's trust agreement. ... Although SPY may fail to own certain Index Securities at any particular time, SPY generally will be substantially invested in Index Securities, which should result in a close correspondence between the performance of the Index and the performance of SPY. ... SPY does not hold or trade futures or swaps and is not a commodity pool. ... The Index includes five hundred (500) selected companies, all of which are listed on national stock exchanges and spans a broad range of major industries. ... Since 1968, the Index has been a component of the U.S. Commerce Department's list of Leading Indicators that track key sectors of the U.S. economy. Current information regarding the market value of the Index is available from market information services. The Index is determined, comprised and calculated without regard to SPY."

As of December 1, 2023, the Underlying ETF had significant investments in information technology companies.

Subsequent Outcome Periods

The Fund will alert existing shareholders to the new Cap at the beginning of each new Outcome Period in the following manner:

1.  Approximately one week prior to the end of the current Outcome Period, the Fund will make a sticker filing that will alert existing shareholders that the Outcome Period is approaching its conclusion and disclose the anticipated Cap range for the next Outcome Period. This filing will be mailed to existing shareholders.

2.  Following the close of business on the last day of the Outcome Period, the Fund will make a sticker filing that discloses the Fund's Cap for the next Outcome Period. This filing will be mailed to existing shareholders.

3.  On the first day of the new Outcome Period, the Fund will file a full prospectus that incorporates the sticker filing from the previous evening which replaces the Caps/dates associated with the previous Outcome Period with the Caps/dates associated with the new Outcome Period. Correspondingly, the Fund will file a revised summary prospectus that reflects such changes.

The information referenced above will also be available on the Fund's website at www.calamos.com.