486BPOS 1 tm215399d1_486bpos.htm 486BPOS

As filed with the Securities and Exchange Commission on February 19, 2021

1933 Act File No. 333-229042

1940 Act File No. 811-21080

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-2

(Check appropriate box or boxes)

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

Pre-Effective Amendment No.

Post-Effective Amendment No. 3

and

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 36

CALAMOS CONVERTIBLE
OPPORTUNITIES AND INCOME FUND

2020 Calamos Court

Naperville, Illinois 60563

(630) 245-7200

Agent for Service

John P. Calamos, Sr.

President

Calamos Convertible Opportunities and Income Fund

2020 Calamos Court

Naperville, Illinois 60563

Copies of Communications to:

Paulita A. Pike		Jeremy Smith
Ropes & Gray LLP		Ropes & Gray LLP
191 North Wacker Drive, 32nd Floor		1211 Avenue of the Americas
Chicago, Illinois 60606		New York, New York 10036

Approximate Date of Proposed Public Offering: From time to time after the effective date of the Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, check the following box ¨.

If any of the securities being registered on this form will be offered on a delayed or continuous basis in reliance on Rule 415 under the Securities Act of 1933, other than securities offered in connection with a dividend reinvestment plan, check the following box. x

If this Form is a registration statement pursuant to General Instruction A.2 or a post-effective amendment thereto, check the following box ¨.

If this Form is a registration statement pursuant to General Instruction B or a post-effective amendment thereto that will become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box ¨.

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction B to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box ¨.

It is proposed that this filing will become effective (check appropriate box)

	¨	when declared effective pursuant to section 8(c)
	x	on March 1, 2021 pursuant to Rule 486(b) as applied by no-action relief granted to Registrant on February 14, 2011

If appropriate, check the following box:

¨This post-effective amendment designates a new effective date for a previously filed registration statement.☐ This form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act and the Securities Act

registration statement number of the earlier effective registration statement for the same offering is.

¨ This Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, and the Securities Act registration statement number of the earlier effective registration statement for the same offering is .

¨ This Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, and the Securities Act registration statement number of the earlier effective registration statement for the same offering is .

Check each box that appropriately characterizes the Registrant:

x Registered closed-end fund.

¨ Business development company.

¨ Interval fund.

x A.2 Qualified.

¨ Well-Known Seasoned Issuer (as defined by Rule 405 under the Securities Act).

¨ Emerging Growth Company (as defined by Rule 12b-2 under the Securities Exchange Act of 1934 (“Exchange Act”).

¨ New Registrant.

Base Prospectus

$100,000,000

Calamos Convertible Opportunities and Income Fund

Common Shares
Preferred Shares
Debt Securities

Calamos Convertible Opportunities and Income Fund (the "Fund," "we," "us," or "our") is a diversified, closed-end management investment company that commenced investment operations in June 2002. Our investment objective is to provide total return through a combination of capital appreciation and current income.

We may offer, on an immediate, continuous or delayed basis, up to $100,000,000 aggregate initial offering price of our common shares (no par value per share), preferred shares (no par value per share) or debt securities, which we refer to in this prospectus collectively as our securities, in one or more offerings. We may offer our common shares, preferred shares and debt securities separately or together, in amounts, at prices and on terms set forth in a prospectus supplement to this prospectus. You should read this prospectus and the related prospectus supplement carefully before you decide to invest in any of our securities.

We may offer our securities directly to one or more purchasers, through agents that we or they designate from time to time, or to or through underwriters or dealers. The prospectus supplement relating to the particular offering will identify any agents or underwriters involved in the sale of our securities, and will set forth any applicable purchase price, fee, commission or discount arrangement between us and such agents or underwriters or among the underwriters and the basis upon which such amount may be calculated. For more information about the manner in which we may offer our securities, see "Plan of Distribution." Our securities may not be sold through agents, underwriters or dealers without delivery or deemed delivery of a prospectus supplement and a prospectus.

Our common shares are listed on the Nasdaq Global Select Market under the symbol "CHI." As of January 31, 2021, the last reported sale price for our common shares was $13.53 per share. As of January 31, 2021, the last reported net asset value for our common shares was $15.07 per share.

Investing in our securities involves certain risks, including the risks associated with the Fund's use of leverage. You could lose some or all of your investment. See "Risk Factors" beginning on page 40 of this prospectus. Shares of closed-end investment companies frequently trade at a discount to their net asset value and this may increase the risk of loss to purchasers of our securities. You should consider carefully these risks together with all of the other information contained in this prospectus and any prospectus supplement before making a decision to purchase our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Beginning on January 1, 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund's shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary. Instead, the reports will be made available on a website, and you will be notified by mail each time a report is posted and provided with a website link to access the report.

If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically by calling 800.582.6959. If you own these shares through a financial intermediary, you may contact your financial intermediary.

You may elect to receive all future reports in paper free of charge. You can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 800.582.6959. If you own these shares through a financial intermediary, you may contact your financial intermediary or follow instructions included with this disclosure to elect to continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held with the fund complex or your financial intermediary.

Prospectus dated March 1, 2021

This prospectus, together with any accompanying prospectus supplement, sets forth concisely the information that you should know before investing. You should read the prospectus and prospectus supplement, which contain important information, before deciding whether to invest in our securities. You should retain the prospectus and prospectus supplement for future reference. A statement of additional information, dated the same date as this prospectus, as supplemented from time to time, containing additional information, has been filed with the Securities and Exchange Commission ("SEC" or the "Commission") and is incorporated by reference in its entirety into this prospectus. You may request a free copy of the statement of additional information, request a free copy of our annual and semi-annual reports, request other information or make shareholder inquiries, by calling toll-free 800.582.6959, by sending an e-mail request to prospectus@calamos.com, or by writing to the Fund at 2020 Calamos Court, Naperville, Illinois 60563. The Fund's annual and semi-annual reports also are available on our website, free of charge, at www.calamos.com, which also provides a link to the Commission's website, as described below, where the Fund's statement of additional information can be obtained. Information included on our website does not form part of this prospectus. You can review documents we have filed on the Commission's website (http://www.sec.gov) for free.

Our securities do not represent a deposit or obligation of, and are not guaranteed or endorsed by, any bank or other insured depository institution and are not federally insured by the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.

TABLE OF CONTENTS

	Page
Prospectus Summary		1
Summary of Fund Expenses		23
Financial Highlights		25
Market and Net Asset Value Information		27
Use of Proceeds		28
The Fund		28
Investment Objective and Principal Investment Strategies		29
Leverage		37
Interest Rate Transactions		43
Risk Factors		45
Management of the Fund		63
Closed-End Fund Structure		67
Certain Federal Income Tax Matters		68
Net Asset Value		76
Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan		78
Description of Securities		83
Rating Agency Guidelines		88
Certain Provisions of the Agreement and Declaration of Trust and By-Laws, Including Antitakeover Provisions		90
Plan of Distribution		92
Custodian, Transfer Agent, Dividend Disbursing Agent and Registrar		95
Legal Matters		95
Experts		95
Available Information		96

You should rely only on the information contained or incorporated by reference in this prospectus and any related prospectus supplement in making your investment decisions. We have not authorized any other person to provide you with different or inconsistent information. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus and any prospectus supplement do not constitute an offer to sell or solicitation of an offer to buy any securities in any jurisdiction where the offer or sale is not permitted. The information appearing in this prospectus and in any prospectus supplement is accurate only as of the dates on their covers. Our business, financial condition and prospects may have changed since such dates. We will advise you of any material changes to the extent required by applicable law.

CAUTIONARY NOTICE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement and the statement of additional information contain "forward-looking statements." Forward-looking statements can be identified by the words "may," "will," "intend," "expect," "estimate," "continue," "plan," "anticipate," and similar terms and the negative of such terms. Such forward-looking statements may be contained in this prospectus as well as in any accompanying prospectus supplement. By their nature, all forward-looking statements involve risks and uncertainties, and actual results could differ materially from those contemplated by the forward-looking statements. Several factors that could materially affect our actual results are the performance of the portfolio of securities we hold, the price at which our shares will trade in the public markets and other factors discussed in our periodic filings with the Commission. Currently known risk factors that could cause actual results to differ materially from our expectations include, but are not limited to, the factors described in the "Risk Factors" section of this prospectus. We urge you to review carefully that section for a more detailed discussion of the risks of an investment in our securities.

Although we believe that the expectations expressed in our forward-looking statements are reasonable, actual results could differ materially from those projected or assumed in our forward-looking statements. Our future financial condition and results of operations, as well as any forward-looking statements, are subject to change and are subject to inherent risks and uncertainties, such as those disclosed in the "Risk Factors" section of this prospectus. All forward-looking statements contained or incorporated by reference in this prospectus or any accompanying prospectus supplement are made as of the date of this prospectus or such accompanying prospectus supplement, as the case may be. Except for our ongoing obligations under the federal securities laws, we do not intend, and we undertake no obligation, to update any forward-looking statement. The forward-looking statements contained in this prospectus, any accompanying prospectus supplement and the statement of additional information are excluded from the safe harbor protection provided by Section 27A of the Securities Act of 1933, as amended (the "1933 Act").

PROSPECTUS SUMMARY

The following summary contains basic information about us and our securities. It is not complete and may not contain all of the information you may want to consider before investing in the Fund. You should review the more detailed information contained in this prospectus and in any related prospectus supplement and in the statement of additional information, especially the information set forth under the heading "Risk Factors" beginning on page 40 of this prospectus.

The Fund

The Fund is a diversified, closed-end management investment company. We commenced operations in June 2002 following our initial public offering. As of January 31, 2021, we had $1.5 billion of total managed assets, including $100 million of outstanding mandatory redeemable preferred shares ("MRP Shares" or "MRPS"). As of January 31, 2021, the Fund had utilized $372.4 million of the $430 million available under the Amended and Restated Liquidity Agreement (the "SSB Agreement") with State Street Bank and Trust Company ("SSB" or "State Street") ($29.9 million of borrowings outstanding, and $342.5 million in structural leverage consisting of collateral received from SSB in connection with securities on loan), representing 24.2% of the Fund's managed assets as of that date, and had $100 million of MRP Shares outstanding, representing 6.5% of the Fund's managed assets. Combined, the borrowings under the SSB Agreement and the outstanding MRP Shares represented 30.6% of the Fund's managed assets. Structural leverage refers to borrowings under the liquidity agreement in respect of which the Fund's interest payments are reduced or eliminated by the Fund's securities lending activities. See "Leverage." Our fiscal year ends on October 31. Our investment objective is to provide total return through a combination of capital appreciation and current income.

Investment Adviser

Calamos Advisors LLC (the "Adviser" or "Calamos") serves as our investment adviser. Calamos is responsible on a day-to-day basis for investment of the Fund's portfolio in accordance with its investment objective and policies. Calamos makes all investment decisions for the Fund and places purchase and sale orders for the Fund's portfolio securities. As of January 31, 2021, Calamos managed approximately $33.4 billion in assets of individuals and institutions. Calamos is a wholly-owned subsidiary of Calamos Investments LLC ("CILLC"). Calamos Asset Management, Inc. is the sole manager of CILLC.

The Fund pays Calamos an annual management fee, payable monthly in arrears, for its investment management services equal to 0.80% of the Fund's average weekly managed assets. "Managed assets" means the total assets of the Fund (including any assets attributable to any leverage that may be outstanding) minus the sum of accrued liabilities (other than debt representing financial leverage). "Net assets" does not include any assets attributable to any leverage that may be outstanding, or other debt representing financial leverage. See "Management of the Fund."

The principal business address of the Adviser is 2020 Calamos Court, Naperville, Illinois 60563.

The Offering

We may offer, from time to time, in one or more offerings or series, together or separately, up to $100,000,000 of our common shares, preferred shares or debt securities, which we refer to, collectively, as the "securities." We may sell our securities through underwriters or dealers, "at the market" to or through a market maker into an existing trading market or otherwise directly to one or more purchasers or through agents or through a combination of methods of sale. The identities of such underwriters, dealers, market makers or agents, as the case may be, will be described in one or more supplements to this prospectus. The securities may be

offered at prices and on terms to be described in one or more supplements to this prospectus. In the event we offer common shares, the offering price per share of our common shares exclusive of any underwriting commissions or discounts will not be less than the net asset value per share of our common shares at the time we make the offering except as permitted by applicable law. To the extent that the Fund issues common shares and current shareholders do not participate, those current shareholders may experience a dilution of their voting rights as new shares are issued to the public. Depending on the facts, any issuance of new common shares may also have the effect of reducing any premium to per share net asset value at which the shares might trade and the market price at which the shares might trade.

Currently, the Fund does not intend to offer any additional preferred shares or debt securities (collectively, "senior securities"), but reserves the right to do so in the future.

We may offer our securities directly to one or more purchasers, through agents that we or they designate from time to time, or to or through underwriters or dealers. The prospectus supplement relating to the relevant offering will identify any agents or underwriters involved in the sale of our securities, and will set forth any applicable purchase price, fee, commission or discount arrangement between us and such agents or underwriters or among underwriters and the basis upon which such amount may be calculated. See "Plan of Distribution." Our securities may not be sold through agents, underwriters or dealers without delivery or deemed delivery of a prospectus and prospectus supplement describing the method and terms of the applicable offering of our securities.

Use of Proceeds

Dividends and Distributions on Common Shares

The Fund intends to distribute to common shareholders all or a portion of its net investment income monthly and net realized capital gains, if any, at least annually. On November 4, 2008, the Commission granted Calamos, on behalf of itself and certain closed-end funds that it manages, including the Fund, or may manage in the future, an order granting an exemption from Section 19(b) of, and Rule 19b-1 under, the Investment Company Act of 1940, as amended (the "1940 Act"), to conditionally permit the Fund to make periodic distributions of long-term capital gains with respect to the Fund's outstanding common shares as frequently as twelve times each year, so long as it complies with the conditions of the order and maintains in effect a distribution policy with respect to its common shares calling for periodic distributions of an amount equal to a fixed amount per share, a fixed percentage of market price per share or a fixed percentage of the Fund's net asset value per share (a "Managed Distribution Policy"). See "Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan — Dividends and Distributions on Common Shares" for a discussion of the requirements under the order permitting the Managed Distribution Policy.

As of January 1, 2018, the Fund adopted such Managed Distribution Policy. Pursuant to such policy, the Fund currently intends to make monthly distributions to common shareholders stated in terms of a fixed cent per common share distribution rate that would be composed of, in addition to net investment income, supplemental amounts generally representing realized capital gains or, possibly, returns of capital representing either unrealized capital gains or a return of original investment. Such distributions, including such supplemental amounts, are sometimes referred to as "managed distributions."

The Fund will seek to establish a distribution rate that roughly corresponds to the Adviser's projections of the total return that could reasonably be expected to be generated by the Fund over an extended period of time, although the distribution rate will not be solely dependent on the amount of income earned or capital gains realized by the Fund. Calamos, in making such projections, may consider long-term historical returns and a variety of other factors. If, for any monthly distribution, net investment income and net realized capital gains were less than the amount of the distribution, the difference would be distributed from the Fund's assets. In addition, in order to make such distributions, the Fund might have to sell a portion of its investment portfolio at a time when independent investment judgment might not dictate such action. The Fund's final distribution for each calendar year will include any remaining net investment income undistributed during the year and may include any remaining net realized capital gains undistributed during the year. The Fund's actual financial performance will likely vary significantly from quarter to quarter and from year to year, and there may be extended periods of up to several years when the distribution rate will exceed the Fund's actual total returns. The Fund's projected or actual distribution rate is not a prediction of what the Fund's actual total returns will be over any specific future period. See "Certain Federal Income Tax Matters — Federal Income Taxation of Common and Preferred Shareholders" and "Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan — Dividends and Distributions on Common Shares" below for a discussion of the short- and long-term implications associated with Fund distributions.

As portfolio and market conditions change, the rate of distributions on the common shares and the Fund's distribution policy could change. To the extent that the total return of the Fund exceeds the distribution rate for an extended period, the Fund may be in a position to increase the distribution rate or distribute supplemental amounts to shareholders. Conversely, if the total return of the Fund is less than the distribution rate for an extended period of time, the Fund will effectively be drawing upon its net assets to meet payments prescribed by its distribution policy. The rate may be modified by the Fund's Board of Trustees from time to time without prior notice to the Fund's shareholders.

Net realized short-term capital gains distributed to shareholders will be taxed as ordinary income for federal income tax purposes and net realized long-term capital gain (if any) will be taxed for federal income tax purposes at long-term capital gain rates. To the extent the Fund distributes an amount in excess of the Fund's current and accumulated earnings and profits, such excess, if any, will be treated by a shareholder for federal income tax purposes as a tax-free return of capital to the extent of the shareholder's adjusted tax basis in their shares and thereafter as a gain from the sale or exchange of such shares. Any such distributions made by the Fund will reduce the shareholder's adjusted tax basis in their shares to the extent that the distribution constitutes a return of capital on a tax basis during any calendar year and, thus, could potentially subject the shareholder to capital gains taxation in connection with a later sale of Fund shares, even if those shares are sold at a price that is lower than the shareholder's original investment price. To the extent that the Fund's distributions exceed the Fund's current and accumulated earnings and profits, the distribution payout rate will exceed the yield generated from the Fund's investments. There is no guarantee that the Fund will realize capital gain in any given year. Distributions are subject to re-characterization for federal income tax purposes after the end of the fiscal year. See "Certain Federal Income Tax Matters."

Pursuant to the Fund's Automatic Dividend Reinvestment Plan, unless a shareholder is ineligible or elects otherwise, all dividends and capital gain distributions on common shares are automatically reinvested in additional common shares of the Fund. However, an investor can choose to receive dividends and distributions in cash. Since investors can participate in the automatic dividend reinvestment plan only if their broker or nominee participates in our plan, you should contact your broker or nominee to confirm that you are eligible to participate in the plan. See "Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan — Automatic Dividend Reinvestment Plan."

Investment Policies

Primary Investments. Under normal circumstances, the Fund invests at least 80% of its managed assets in a diversified portfolio of convertible securities and non-convertible income securities.¹ The portion of the Fund's assets invested in convertible securities and non-convertible income securities will vary from time to time consistent with the Fund's investment objective, changes in equity prices and changes in interest rates and other economic and market factors, although, under normal circumstances, the Fund will invest at least 35% of its managed assets in convertible securities. The Fund invests in securities with a broad range of maturities. The average term to maturity of the Fund's securities typically will range from five to ten years. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies."

Under normal circumstances, the Fund will invest at least 35% of its managed assets in convertible securities. A convertible security is a debt security, debenture, note or preferred stock that is exchangeable for an equity security (typically common stock of the same issuer) at a predetermined price (the "conversion price"). Depending upon the relationship of the conversion price to the market value of the underlying security, a convertible security may trade more like an equity security than a debt instrument. The Fund may invest in convertible securities of any rating. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies — Convertible Securities."

Synthetic Convertible Instruments. The Fund may invest in "synthetic" convertible instruments. A synthetic convertible instrument is a financial instrument (or two or more securities held in tandem) that is designed to simulate the economic characteristics of another instrument (i.e., a convertible security) through the combined economic features of a collection of other securities or assets. Calamos may create a synthetic convertible instrument by combining separate securities that possess the two principal characteristics of a true convertible security, i.e., a fixed-income security ("fixed-income component", which may be a convertible or non-convertible security) and the right to acquire an equity security ("convertible component"). The fixed-income component is achieved by investing in fixed-income securities such as bonds, preferred stocks and money market instruments. The convertible component is achieved by investing in warrants or options to buy common stock at a certain exercise price, or options on a stock index.

The Fund may also invest in synthetic convertible instruments created by third parties, typically investment banks. Synthetic convertible instruments created by such parties may be designed to simulate the characteristics of traditional convertible securities or may be designed to alter or emphasize a particular feature. Traditional convertible securities typically offer the opportunity for stable cash flows with the ability to participate in capital appreciation of the underlying common stock. Traditional convertible securities are exercisable at the option of the holder. Synthetic convertible instruments may alter these characteristics by offering enhanced yields in exchange for reduced capital appreciation, additional risk of loss, or any combination of these features. Synthetic convertible instruments may include structured notes, equity-linked notes, mandatory convertibles and combinations of securities and instruments, such as a debt instrument combined with a forward contract. The Fund's holdings of synthetic convertible instruments are considered convertible securities for purposes of the Fund's policy to invest at least 35% of its managed assets in convertible securities and 80% of its managed assets in a diversified portfolio of convertible securities and non-convertible income securities. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies — Synthetic Convertible Instruments."

1 This is a non-fundamental policy and may be changed by the Board of Trustees of the Fund provided that shareholders are provided with at least 60 days' prior written notice of any change as required by the rules under the 1940 Act.

Non-Convertible Income Securities. The Fund will also invest in non-convertible income securities. The Fund's investments in non-convertible income securities may have fixed or variable principal payments and all types of interest rate and dividend payment and reset terms, including fixed rate, adjustable rate, zero coupon, contingent, deferred, payment in kind and auction rate features. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies — Non-Convertible Income Securities."

High Yield Securities. A substantial portion of the Fund's assets may be invested in below investment grade (high yield, high risk) securities for either current income or capital appreciation or both. These securities are rated Ba or lower by Moody's Investors Service, Inc. ("Moody's") or BB or lower by Standard & Poor's Financial Services, LLC, a subsidiary of The McGraw-Hill Companies, Inc. ("Standard & Poor's") or are unrated securities of comparable quality as determined by Calamos, the Fund's investment adviser. The Fund may invest in high yield securities of any rating. The Fund may, but currently does not intend to, invest up to 5% of its managed assets in distressed securities that are in default or the issuers of which are in bankruptcy. Non-convertible debt securities rated below investment grade are commonly referred to as "junk bonds" and are considered speculative with respect to the issuer's capacity to pay interest and repay principal. Below investment grade securities involve greater risk of loss, are subject to greater price volatility and are less liquid, especially during periods of economic uncertainty or change, than higher rated securities. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies — High Yield Securities."

Options Writing. The Fund may seek to generate income from option premiums by writing (selling) options. The Fund may write (sell) call options (i) on a portion of the equity securities (including equity securities obtainable by the Fund through the exercise of its rights with respect to convertible securities it owns) in the Fund's portfolio and (ii) on broad-based securities indices (such as the Standard and Poor's 500^® Index ("S&P 500") or the MSCI EAFE^® Index ("MSCI EAFE"), which is an index of international equity stocks) or certain ETFs (exchange-traded funds) that trade like common stocks but seek to replicate such market indices.

In addition, to seek to offset some of the risk of a potential decline in value of certain long positions, the Fund may also purchase put options on individual securities, broad-based securities indices (such as the S&P 500 or the MSCI EAFE), or certain ETFs that trade like common stocks but seek to replicate such market indices. See "Investment Objective and Principal Investment Strategies — Options Writing."

Rule 144A Securities. The Fund may invest without limit in certain securities ("Rule 144A Securities"), such as convertible and debt securities, that are typically purchased in transactions exempt from the registration requirements of the 1933 Act pursuant to Rule 144A under that Act. Rule 144A Securities may only be sold to qualified institutional buyers, such as the Fund. Any resale of these securities must generally be effected through a sale that is registered under the 1933 Act or otherwise exempted or excepted from such registration requirements. Under the supervision and oversight of the Fund's Board of Trustees, Calamos will determine whether Rule 144A Securities are liquid. Typically, the Fund purchases Rule 144A Securities only if Calamos has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult. See "Investment Objective and Principal Investment Strategies — Principal Investment Strategies — Rule 144A Securities."

in possession financings pursuant to Chapter 11 of the U.S. Bankruptcy Code, obligations of a borrower issued in connection with a restructuring pursuant to Chapter 11 of the U.S. Bankruptcy Code, leveraged buy-out loans, leveraged recapitalization loans, receivables purchase facilities, and privately placed notes. The Fund may invest in a corporate loan at origination as a co-lender or by acquiring in the secondary market participations in, assignments of or novations of a corporate loan. By purchasing a participation, the Fund acquires some or all of the interest of a bank or other lending institution in a loan to a corporate or government borrower. The participations typically will result in the Fund having a contractual relationship only with the lender not the borrower. The Fund will have the right to receive payments of principal, interest and any fees to which it is entitled only from the lender selling the participation and only upon receipt by the lender of the payments from the borrower. Many such loans are secured, although some may be unsecured. Such loans may be in default at the time of purchase. Loans that are fully secured offer the Fund more protection than an unsecured loan in the event of non-payment of scheduled interest or principal. However, there is no assurance that the liquidation of collateral from a secured loan would satisfy the corporate borrower's obligation, or that the collateral can be liquidated. Direct debt instruments may involve a risk of loss in case of default or insolvency of the borrower and may offer less legal protection to the Fund in the event of fraud or misrepresentation. In addition, loan participations involve a risk of insolvency of the lending bank or other financial intermediary. The markets in such loans are not regulated by federal securities laws or the Commission.

Other Securities. The Fund may invest in other securities of various types to the extent consistent with its investment objective. Normally, the Fund invests substantially all of its assets to meet its investment objective. For temporary defensive purposes, the Fund may depart from its principal investment strategies and invest part or all of its assets in securities with remaining maturities of less than one year or cash equivalents; or it may hold cash. During such periods, the Fund may not be able to achieve its investment objective. There are no restrictions as to the ratings of debt securities acquired by the Fund or the portion of the Fund's assets that may be invested in debt securities in a particular ratings category. For more information on the types of derivatives that the Fund invests in, see "Investment Objective and Principal Investment Strategies — Principal Investment Strategies" in this prospectus and "Investment Objective and Policies" in the statement of additional information.

Use of Leverage by the Fund

The Fund currently uses, and may in the future use, financial leverage. The Fund has obtained financial leverage (i) under the SSB Agreement that allows the Fund to borrow up to $430 million and (ii) through the issuance of three series of MRP Shares with an aggregate liquidation preference of $100 million, as described in greater detail below. The SSB Agreement provides for securities lending and securities repurchase transactions that may offset some of the interest rate payments that would otherwise be due in respect of the borrowings under the SSB Agreement. The Fund's outstanding MRP Shares include 1,330,000 Series A MRP Shares, with an aggregate liquidation preference of $33,250,000 and a mandatory redemption date of September 6, 2022; 1,330,000 Series B MRP Shares, with an aggregate liquidation preference of $33,250,000 and a mandatory redemption date of September 6, 2024; and 1,340,000 Series C MRP Shares, with an aggregate liquidation preference of $33,500,000 and a mandatory redemption date of September 6, 2027. The Series A, Series B and Series C MRP Shares are to pay monthly cash dividends initially at rates of 3.70%, 4.00% and 4.24%, respectively, subject to adjustment under certain circumstances. Additional details regarding the SSB Agreement and the MRP Shares are included under "Leverage."

As of January 31, 2021, the Fund had utilized $372.4 million of the $430 million available under the SSB Agreement ($29.9 million in borrowings outstanding, and $342.5 million in structural leverage consisting of collateral received from SSB in connection with securities on loan), representing 24.2% of the Fund's managed assets as of that date, and had $100 million of MRP Shares outstanding, representing 6.5% of the Fund's managed

assets. Combined, the borrowings under the SSB Agreement and the outstanding MRP Shares represented 30.6% of the Fund's managed assets.

The Fund may make further use of financial leverage through the issuance of additional preferred shares or may borrow money or issue additional debt securities to the extent permitted under the 1940 Act or under the SSB Agreement. As a non-fundamental policy, the Fund may not issue preferred shares or borrow money and/or issue debt securities with an aggregate liquidation preference and aggregate principal amount exceeding 38% of the Fund's managed assets measured at the time of borrowing or issuance of the new securities. However, the Board of Trustees reserves the right to issue preferred shares or debt securities or borrow to the extent permitted by the 1940 Act. See "Leverage." The holders of preferred shares or debt, if any, on the one hand, and the holders of the common shares, on the other, may have interests that conflict with each other in certain situations. See "Description of Securities — Preferred Shares" and "Certain Provisions of the Agreement and Declaration of Trust and By-Laws, Including Antitakeover Provisions."

Because Calamos' investment management fee is a percentage of the Fund's managed assets, Calamos' fee will be higher if the Fund is leveraged and Calamos will have an incentive to be more aggressive and leverage the Fund. Consequently, the Fund and Calamos may have differing interests in determining whether to leverage the Fund's assets. Any additional use of leverage by the Fund effected through new, additional or increased credit facilities or the issuance of preferred shares would require approval by the Board of Trustees of the Fund. In considering whether to approve the use of additional leverage through those means, the Board would be presented with all relevant information necessary to make a determination whether or not additional leverage would be in the best interests of the Fund, including information regarding any potential conflicts of interest. For further information about the Fund's financial leverage, see "Use of Leverage by the Fund."

For further information about the effects of the Fund's financial leverage and an illustration of the hypothetical effect on the return to a holder of the Fund's common shares of the leverage obtained by borrowing under the Fund's financing package, see "Effects of Leverage." For further information about leveraging, see "Risk Factors — Fund Risks — Leverage Risk."

Interest Rate Transactions

In order to seek to reduce the interest rate risk inherent in the Fund's underlying investments and capital structure, the Fund, if Calamos deems market conditions favorable, may enter into over-the-counter interest rate swap, cap or floor transactions to attempt to protect itself from increasing dividend or interest expenses on its leverage. The use of interest rate swaps and caps is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary portfolio security transactions.

In an interest rate swap, the Fund would agree to pay to the other party to the interest rate swap (which is known as the "counterparty") a fixed rate payment in exchange for the counterparty agreeing to pay to the Fund a payment at a variable rate that is expected to approximate the rate on any variable rate payment obligation on the Fund's leverage. The payment obligations would be based on the notional amount of the swap.

In an interest rate cap, the Fund would pay a premium to the counterparty to the interest rate cap and, to the extent that a specified variable rate index exceeds a predetermined fixed rate, would receive from the counterparty payments of the difference based on the notional amount of such cap. There can be no assurance that the Fund will use interest rate transactions or that, if used, their use will be beneficial to the Fund. Depending on the state of interest rates in general, the Fund's use of interest rate swap or cap transactions could enhance or harm the overall performance of the common shares. See "Interest Rate Transactions."

Conflicts of Interest

Conflicts of interest may arise from the fact that Calamos and its affiliates carry on substantial investment activities for other clients, in which the Fund does not have an interest. Calamos or its affiliates may have financial incentives to favor certain of these accounts over the Fund. Any of their proprietary accounts or other customer accounts may compete with the Fund for specific trades. Calamos or its affiliates may give advice and recommend securities to, or buy or sell securities for, other accounts and customers, which advice or securities recommended may differ from advice given to, or securities recommended or bought or sold for, the Fund, even though their investment objectives may be the same as, or similar to, the Fund's investment objective.

Situations may occur when the Fund could be disadvantaged because of the investment activities conducted by Calamos and its affiliates for their other accounts. Such situations may be based on, among other things, the following: (1) legal or internal restrictions on the combined size of positions that may be taken for the Fund or the other accounts, thereby limiting the size of the Fund's position; (2) the difficulty of liquidating an investment for the Fund or the other accounts where the market cannot absorb the sale of the combined position; or (3) limits on co-investing in negotiated transactions under the 1940 Act. See "Investment Objective and Principal Investment Strategies — Conflicts of Interest."

Fund Risks

The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below, including Management Risk, Portfolio Selection Risk, Equity Securities Risk, Emerging Market Risk and Foreign Securities Risk, among others, is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears.

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.

Antitakeover Provisions. The Fund's Agreement and Declaration of Trust and By-Laws include provisions that could limit the ability of other entities or persons to acquire control of the Fund or to change the composition of its Board of Trustees. Such provisions could limit the ability of shareholders to sell their shares at a premium over prevailing market prices by discouraging a third party from seeking to obtain control of the Fund. These provisions include staggered terms of office for the Trustees, advance notice requirements for shareholder proposals, and super-majority voting requirements for certain transactions with affiliates, converting the Fund to an open-end investment company or a merger, asset sale or similar transaction. Holders of preferred shares have voting rights in addition to and separate from the voting rights of common shareholders with respect to certain of these matters. Holders of any preferred shares, voting separately as a single class, have the right to elect at least two Trustees at all times. See "Description of Securities — Preferred Shares" and "Certain Provisions of the Agreement and Declaration of Trust and By-Laws, Including Antitakeover Provisions." The holders of preferred shares or debt, if any, on the one hand, and the holders of the common shares, on the other, may have interests that conflict with each other in certain situations, including conflicts that relate to the fees and expenses of the Fund. For more information on potential conflicts of interest between holders of common shares and holders of preferred shares, see "Fund Risks — Leverage Risk." See also "Risk Factors — Fund Risks — Antitakeover Provisions."

Cash Holdings Risk. To the extent the Fund holds cash positions, the Fund risks achieving lower returns and potential lost opportunities to participate in market appreciation which could negatively impact the Fund's performance and ability to achieve its investment objective.

Contingent Liabilities Risk. Entering into derivative contracts in order to pursue the Fund's various hedging strategies could require the Fund to fund cash payments in the future under certain circumstances, including an event of default or other early termination event, or the decision by a counterparty to request margin in the form of securities or other forms of collateral under the terms of the derivative contract or applicable laws. The amounts due with respect to a derivative contract would generally be equal to the unrealized loss of the open positions with the respective counterparty and could also include other fees and charges. These payments are contingent liabilities and therefore may not appear on the Fund's balance sheet. The Fund's ability to fund these contingent liabilities will depend on the liquidity of the Fund's assets and access to capital at the time, and the need to fund these contingent liabilities could adversely impact our financial condition.

Convertible Securities Risk. The value of a convertible security is influenced by both the yield of non- convertible securities of comparable issuers and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value tends to increase as prevailing interest rate levels decline.

However, a convertible security's market value tends to reflect the market price of the common stock of the issuing company when that stock price is greater than the convertible security's "conversion price." The conversion price is defined as the predetermined price at which the convertible security could be exchanged for the associated stock. As the market price of the underlying common stock declines, the price of the convertible security tends to be influenced more by the yield of the convertible security and changes in interest rates. Thus, the convertible security may not decline in price to the same extent as the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. See "Risk Factors — Fund Risks — Convertible Securities Risk."

Counterparty and Settlement Risk. Trading options, futures contracts, swaps and other derivative financial instruments entails credit risk with respect to the counterparties. Such instruments when traded over the counter do not include the same protections as may apply to trading derivatives on organized exchanges. Substantial losses may arise from the insolvency, bankruptcy or default of a counterparty and risk of settlement default of parties with whom it trades securities. This risk may be heightened during volatile market conditions. Settlement mechanisms in emerging markets are generally less developed and reliable than those in more developed countries, thus increasing the risks. In the past, broker-dealers and other financial institutions have experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. Although Calamos monitors the creditworthiness of the Fund's counterparties, there can be no assurance that the Fund's counterparties will not experience similar difficulties, possibly resulting in losses to the Fund. If a counterparty becomes bankrupt, or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances. Material exposure to a single or small group of counterparties increases the Fund's counterparty risk. See "Risk Factors — Fund Risks — Counterparty and Settlement Risk."

"Covenant-Lite" Loans Risk. Some of the loans in which the Fund may invest may be "covenant-lite" loans, which means the loans contain fewer or no maintenance covenants than other loans and do not include terms which allow the lender to monitor the performance of the borrower and declare a default if certain criteria are breached. The Fund may experience delays in enforcing its rights on its holdings of covenant-lite loans.

Credit Risk. An issuer of a fixed income security could be downgraded or default. If the Fund holds securities that have been downgraded, or that default on payment, the Fund's performance could be negatively affected.

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. The Fund's investment adviser may determine not to hedge currency risks, even if suitable instruments appear to be available.

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 a 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 the Adviser, 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.

Debt Securities Risk. The Fund may invest in debt securities, including corporate bonds and high yield securities. In addition to the risks described elsewhere in this prospectus (such as high yield securities risk and interest rate risk), debt securities are subject to certain additional risks, including issuer risk and reinvestment risk. Issuer risk is the risk that the value of debt securities may decline for a number of reasons which directly relate to the issuer, such as management performance, leverage and reduced demand for the issuer's goods and services. Reinvestment risk is the risk that income from the Fund's portfolio will decline if the Fund invests the proceeds from matured, traded or called bonds at market interest rates that are below the Fund portfolio's current earnings rate. A decline in income could affect the market price of the Fund's common shares or the overall return of the Fund.

Default Risk. Default risk refers to the risk that a company that issues a convertible or debt security will be unable to fulfill its obligations to repay principal and interest. The lower a debt security is rated, the greater its default risk. As a result, the Fund may incur cost and delays in enforcing its rights against the defaulting issuer. See "Risk Factors — Fund Risks — Default Risk."

Derivatives Risk. Generally, derivatives are financial contracts whose value depends on, or is derived from, the value of an underlying asset, reference rate or index, and may relate to individual debt or equity instruments, interest rates, currencies or currency exchange rates, commodities, related indexes and other assets. The Fund may utilize a variety of derivative instruments including, but not limited to, interest rate swaps, convertible securities, synthetic convertible instruments, options on individual securities, index options, long calls, covered calls, long puts, cash-secured short puts and protective puts for hedging, risk management and investment purposes. The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. The use of derivative instruments may have risks including, among others, leverage risk, duration mismatch risk, correlation risk, liquidity risk, interest rate risk, volatility risk, credit risk, management risk and counterparty risk. Derivatives also involve the risk of mispricing or improper valuation and the risk that changes in the value of a derivative may not correlate perfectly with an underlying asset, interest rate or index. Suitable derivative transactions may not be available in all circumstances and there can be no assurance that the Fund will engage in these transactions to reduce exposure to other risks when that would be beneficial. Furthermore, the skills needed to employ derivatives strategies are different from those needed to select portfolio securities and, in connection with such strategies, the Fund makes predictions with respect to market conditions, liquidity, currency movements, market values, interest rates and other applicable factors, which may be

inaccurate. Thus, the use of derivative investments may require the Fund to sell or purchase portfolio securities at inopportune times or for prices below or above the current market values, may limit the amount of appreciation the Fund can realize on an investment or may cause the Fund to hold a security that it might otherwise want to sell. Tax rules governing the Fund's transactions in derivative instruments may also 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, among other things, 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. In addition, there may be situations in which the Fund elects not to use derivative investments that result in losses greater than if they had been used.

Amounts paid by the Fund as premiums and cash or other assets held in margin accounts with respect to the Fund's derivative instruments would not be available to the Fund for other investment purposes, which may result in lost opportunities for gain.

Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance. See "Risk Factors — Fund Risks — Derivatives Risk" for a more complete discussion of the risks associated with derivatives transactions.

Duration Risk. Duration measures the time-weighted expected cash flows of a fixed-income security, which can determine its sensitivity to changes in the general level of interest rates. The value of securities with longer durations tend to be more sensitive to interest rate changes than securities with shorter durations. The longer the Fund's dollar-weighted average duration, the more its value can generally be expected to be sensitive to interest rate changes than a fund with a shorter dollar-weighted average duration. Duration differs from maturity in that it considers a security's coupon payments in addition to the amount of time until the security matures. Various techniques may be used to shorten or lengthen the Fund's duration. As the value of a security changes over time, so will its duration.

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 adversely affect the value of the Fund's investments and hurt those countries' economies and securities markets. See "Risk Factors — Fund Risks — Emerging Markets Risk."

Equity Securities Risk. Equity investments are subject to greater fluctuations in market value than other asset classes as a result of such factors as the issuer's business performance, investor perceptions, stock market trends and general economic conditions. Equity securities are subordinated to bonds and other debt instruments in a company's capital structure in terms of priority to corporate income and liquidation payments. The Fund may invest in preferred stocks and convertible securities of any rating, including below investment grade. Below investment grade securities or comparable unrated securities are considered predominantly speculative with respect to the issuer's ability to pay interest and principal and are susceptible to default or decline in market value due to adverse economic and business developments. The market values for below investment grade securities tend to be very volatile, and these securities are generally less liquid than investment grade debt securities. For these reasons, your investment in the Fund is subject to the following specific risks:

• increased price sensitivity to changing interest rates and to a deteriorating economic environment;

• greater risk of loss due to default or declining credit quality;

• adverse company specific events are more likely to render the issuer unable to make interest and/or principal payments; and

• if a negative perception of the below investment grade market develops, the price and liquidity of below investment grade securities may be depressed. This negative perception could last for a significant period of time.

Foreign Securities Risk. Investments in non-U.S. issuers may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced to the extent that the Fund invests a significant portion of its non-U.S investments in one region or in the securities of emerging market issuers. See also "— Emerging Markets Risk" below. These risks may include:

• less information may be available about non-U.S. issuers or markets due to less rigorous disclosure or accounting standards or regulatory practices in foreign jurisdictions;

• many non-U.S. markets are smaller, less liquid and more volatile. In a changing market, Calamos may not be able to sell the Fund's portfolio securities at times, in amounts and at prices it considers reasonable;

• an adverse effect of currency exchange rate changes or controls on the value of the Fund's investments;

• the economies of non-U.S. countries may grow at slower rates than expected or may experience a downturn or recession;

• economic, political and social developments may adversely affect the securities markets in foreign jurisdictions, including expropriation and nationalization;

• the difficulty in obtaining or enforcing a court judgment in non-U.S. countries;

• restrictions on foreign investments in non-U.S. jurisdictions;

• difficulties in effecting the repatriation of capital invested in non-U.S. countries;

• withholding and other non-U.S. taxes may decrease the Fund's return;

• the ability for the Public Company Accounting Oversight Board, which regulates auditors of U.S. public companies, is unable to inspect audit work papers in certain foreign countries;

• often limited rights and few practical remedies to pursue shareholder claims, including class actions or fraud claims, and the ability of the Commission, the U.S. Department of Justice and other authorities to bring and enforce actions against foreign issuers or foreign persons is limited; and

• dividend income the Fund receives from foreign securities may not be eligible for the special tax treatment applicable to qualified dividend income.

Based upon the Fund's test for determining whether an issuer is a "foreign issuer" as described above, it is possible that an issuer of securities in which the Fund invests could be organized under the laws of a foreign country, yet still conduct a substantial portion of its business in the U.S. or have substantial assets in the U.S. In this case, such a "foreign issuer" may be subject to the market conditions in the U.S. to a greater extent than it may be subject to the market conditions in the country of its organization. See "Risk Factors — Fund Risks — Foreign Securities Risk." See also " — Non-U.S. Government Obligation Risk."

Forward Foreign Currency Contract Risk. Forward foreign currency contracts are contractual agreements to purchase or sell a specified currency at a specified future date (or within a specified time period) at a price set at the time of the contract. The Fund may not fully benefit from, or may lose money on, forward foreign currency transactions if changes in currency exchange rates do not occur as anticipated or do not correspond accurately to changes in the value of the Fund's holdings.

Geographic Concentration Risk. Investments in a particular country or geographic region may be particularly susceptible to political, diplomatic or economic conditions and regulatory requirements. To the extent the Fund concentrates its investments in a particular country, region or group of regions, the Fund may be more volatile than a more geographically diversified fund.

High Yield Securities Risk. The Fund may invest in high yield securities of any rating. Investment in high yield securities involves substantial risk of loss. Below investment grade non-convertible debt securities or comparable unrated securities are commonly referred to as "junk bonds" and are considered predominantly speculative with respect to the issuer's ability to pay interest and principal and are susceptible to default or decline in market value due to adverse economic and business developments. The market values for high yield securities tend to be very volatile, and these securities are less liquid than investment grade debt securities. For these reasons, your investment in the Fund is subject to the following specific risks:

• increased price sensitivity to changing interest rates and to a deteriorating economic environment;

• greater risk of loss due to default or declining credit quality;

• adverse company specific events are more likely to render the issuer unable to make interest and/or principal payments; and

• if a negative perception of the high yield market develops, the price and liquidity of high yield securities may be depressed. This negative perception could last for a significant period of time.

The secondary market for high yield securities may not be as liquid as the secondary market for more highly rated securities, a factor which may have an adverse effect on the Fund's ability to dispose of a particular security. There are fewer dealers in the market for high yield securities than for investment grade obligations. The prices quoted by different dealers may vary significantly and the spread between the bid and asked price is generally much larger than for higher quality instruments. Under adverse market or economic conditions, the secondary market for securities could contract further, independent of any specific adverse changes in the condition of a particular issuer, and these instruments may become illiquid. As a result, the Fund could find it more difficult to sell these securities or may be able to sell the securities only at prices lower than if such securities were widely traded. Prices realized upon the sale of such lower rated or unrated securities, under these circumstances, may be less than the prices used in calculating the Fund's net asset value. See "Risk Factors — Fund Risks — High Yield Securities Risk."

Interest Rate Risk. In addition to the risks described above, debt securities, including high yield securities, are subject to certain risks, including:

• if interest rates go up, the value of debt securities in the Fund's portfolio generally will decline;

repurchase the security prior to its stated maturity. An issuer may redeem an obligation if the issuer can refinance the debt at a lower cost due to declining interest rates or an improvement in the credit standing of the issuer;

• during periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the estimated period until the security is paid in full, and reduce the value of the security. This is known as extension risk;

• rising interest rates could result in an increase in the cost of the Fund's leverage and could adversely affect the ability of the Fund to meet asset coverage requirements with respect to leverage;

• variable rate securities generally are less sensitive to interest rate changes but may decline in value if their interest rates do not rise as much, or as quickly, as interest rates in general. When the Fund holds variable rate securities, a decrease in market interest rates will adversely affect the income received from such securities and the net asset value ("NAV") of the Fund's shares; and

• the risks associated with rising interest rates may be particularly acute in the current market environment because market interest rates are currently near historically low levels. Thus, the Fund currently faces a heightened level of interest rate risk. To the extent the Federal Reserve Board raises interest rates, there is a risk that interest rates across the financial system may rise. Increases in volatility and interest rates in the fixed-income market may expose the Fund to heightened interest rate risk.

Many financial instruments use or may use a floating rate based on LIBOR, which is the offered rate for short-term Eurodollar deposits between major international banks. LIBOR is expected to be phased out by the end of 2021. On November 30, 2020, the administrator of LIBOR announced a delay in the phase out of a majority of the U.S. dollar LIBOR publications until June 30, 2023, with the remainder of LIBOR publications to still end at the end of 2021. There remains uncertainty regarding the future utilization of LIBOR and the nature of any replacement rate. As such, the potential effect of a transition away from LIBOR on the Fund or the financial instruments in which the Fund invests can be difficult to ascertain. See "Risk Factors — Fund Risks — Interest Rate Risk."

Leverage Risk. The Fund has issued indebtedness and preferred shares and may borrow money or issue debt securities as permitted by the 1940 Act. As of January 31, 2021, the Fund has leverage in the form of borrowings under the SSB Agreement and outstanding MRP Shares. Leverage is the potential for the Fund to participate in gains and losses on an amount that exceeds the Fund's investment. The borrowing of money or issuance of debt securities and preferred shares represents the leveraging of the Fund's common shares. As a non-fundamental policy, the Fund may not issue preferred shares or borrow money and/or issue debt securities with an aggregate liquidation preference and aggregate principal amount exceeding 38% of the Fund's managed assets as measured at the time of borrowing or issuance of the new securities. However, the Board of Trustees reserves the right to issue preferred shares or debt securities or borrow to the extent permitted by the 1940 Act and the Fund's policies. See "Leverage."

Leverage creates risks which may adversely affect the return for the holders of common shares, including:

• the likelihood of greater volatility in the net asset value and market price of the Fund's common shares;

• fluctuations in the dividend rates on any preferred shares borne by the Fund or in interest rates on borrowings and short-term debt;

• increased operating costs, which are effectively borne by common shareholders, may reduce the Fund's total return; and

• the potential for a decline in the value of an investment acquired with borrowed funds, while the Fund's obligations under such borrowing or preferred shares remain fixed.

In addition, the rights of lenders and the holders of preferred shares and debt securities issued by the Fund will be senior to the rights of the holders of common shares with respect to the payment of dividends or to the payment of assets upon liquidation. Holders of preferred shares have voting rights in addition to and separate from the voting rights of common shareholders. See "Description of Securities — Preferred Shares" and "Certain Provisions of the Agreement and Declaration of Trust and By-Laws, Including Antitakeover Provisions." The holders of preferred shares or debt, if any, on the one hand, and the holders of the common shares, on the other, may have interests that conflict in certain situations.

Leverage is a speculative technique that could adversely affect the returns to common shareholders. Leverage can cause the Fund to lose money and can magnify the effect of any losses. To the extent the income or capital appreciation derived from securities purchased with funds received from leverage exceeds the cost of leverage, the Fund's return will be greater than if leverage had not been used. Conversely, if the income or capital appreciation from the securities purchased with such funds is not sufficient to cover the cost of leverage or if the Fund incurs capital losses, the return of the Fund will be less than if leverage had not been used, and therefore the amount available for distribution to common shareholders as dividends and other distributions will be reduced or potentially eliminated.

The Fund will pay, and common shareholders will effectively bear, any costs and expenses relating to any borrowings and to the issuance and ongoing maintenance of preferred shares or debt securities. Such costs and expenses include the higher management fee resulting from the use of any such leverage, offering and/or issuance costs, and interest and/or dividend expense and ongoing maintenance. These conditions may, directly or indirectly, result in higher leverage costs to common shareholders.

Certain types of borrowings may result in the Fund being subject to covenants in credit agreements, including those relating to asset coverage, borrowing base and portfolio composition requirements and additional covenants that may affect the Fund's ability to pay dividends and distributions on common shares in certain instances. The Fund may also be required to pledge its assets to the lenders in connection with certain types of borrowings. The Fund may be subject to certain restrictions on investments imposed by guidelines of and covenants with rating agencies which may issue ratings for the preferred shares or short-term debt instruments issued by the Fund. These guidelines and covenants may impose asset coverage or portfolio composition requirements that are more stringent than those imposed by the 1940 Act. The Board reserves the right to change the amount and type of leverage that the Fund uses, and reserves the right to implement changes to the Fund's borrowings that it believes are in the long-term interests of the Fund and its shareholders, even if such changes impose a higher interest rate or other costs or impacts over the intermediate, or short-term time period. There is no guarantee that the Fund will maintain leverage at the current rate, and the Board reserves the right to raise, decrease, or eliminate the Fund's leverage exposure. See "Prospectus Summary — Use of Leverage by the Fund."

Liquidity Risk. The Fund may invest without limit in securities that, at the time of investment, are illiquid (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). Illiquid securities may be difficult to dispose of at a fair price at the times when the Fund believes it is desirable to do so. Investment of the Fund's assets in illiquid securities may restrict the Fund's ability to take advantage of market opportunities. The market price of illiquid securities generally is more volatile than that of more liquid securities, which may adversely affect the price that the Fund pays for or recovers upon the sale of illiquid securities. Illiquid securities are also more difficult to value and may be fair valued by the Board, in which case Calamos' judgment may play a greater role in the valuation process. The risks associated with illiquid

securities may be particularly acute in situations in which the Fund's operations require cash and could result in the Fund borrowing to meet its short-term needs or incurring losses on the sale of illiquid securities. See "Risk Factors — Fund Risks — Liquidity Risk."

Loan Risk. The Fund may invest in loans which may not be (i) rated at the time of investment, (ii) registered with the SEC or (iii) listed on a securities exchange. There may not be as much public information available regarding these loans as is available for other Fund investments, such as exchange-listed securities. As well, there may not be an active trading market for some loans, meaning they may be illiquid and more difficult to value than other more liquid securities. Settlement periods for loans are longer than for exchange-traded securities, typically ranging between 1 and 3 weeks, and in some cases much longer. There is no central clearinghouse for loan trades, and the loan market has not established enforceable settlement standards or remedies for failure to settle. Because the interest rates of floating-rate loans in which the Fund may invest may reset frequently, if market interest rates fall, the loans' interest rates will be reset to lower levels, potentially reducing the Fund's income. Because the adviser may wish to invest in the publicly-traded securities of an obligor, the Fund may not have access to material non-public information regarding the obligor to which other investors have access.

Management Risk. Calamos' judgment about the attractiveness, relative value or potential appreciation of a particular sector, security or investment strategy may prove to be incorrect. See "Risk Factors — Fund Risks — Management Risk."

Master Limited Partnerships Risk. Investments in MLPs involve risks that differ from investments in common stock. Holders of MLP common units are subject to certain risks inherent in the structure of MLPs, including (i) tax risks, (ii) risk related to limited control of management or the general partner or managing member, (iii) limited rights to vote on matters affecting the MLP, except with respect to extraordinary transactions, (iv) conflicts of interest between the general partner or managing member and its affiliates, on the one hand, and the limited partners or members, on the other hand, including those arising from incentive distribution payments or corporate opportunities, and (v) cash flow risks. MLP common units and other equity securities can be affected by macro-economic and other factors affecting the stock market in general, expectations of interest rates, investor sentiment towards MLPs or the energy sector, changes in a particular issuer's financial condition, or unfavorable or unanticipated poor performance of a particular issuer (in the case of MLPs, generally measured in terms of distributable cash flow). Prices of common units of individual MLPs and other equity securities also can be affected by fundamentals unique to the partnership or company, including cash flow growth, cash generating power and distribution coverage.

Although certain MLPs may trade on national securities exchanges, certain MLPs may trade less frequently than those of larger companies due to their market capitalizations. Due to limited trading volumes of certain MLPs, the prices of such MLPs may display abrupt or erratic movements at times. Additionally, it may be more difficult for the Fund to buy and sell significant amounts of such securities without an unfavorable impact on prevailing market prices. The Fund's investment in securities that are less actively traded or over time experience decreased trading volume may restrict its ability to dispose of the securities at a fair price. Such a situation may prevent the Fund from limiting losses or realizing gains. This also may adversely affect the Fund's ability to make dividend distributions to shareholders.

income, gains, losses, deductions and expenses. A change in current tax law, or a change in the business of a given MLP, could result in an MLP being treated as a corporation for U.S. federal income tax purposes. As a result, the amount of cash available for distribution by the MLP would be reduced and the after-tax return to the Fund with respect to its investment in such MLPs would be materially reduced. Thus, if any of the MLPs owned by the Fund were treated as corporations for U.S. federal income tax purposes, it could result in a reduction in the value of the Fund.

Maturity Risk. Interest rate risk will generally affect the price of a fixed income security more if the security has a longer maturity. Fixed income securities with longer maturities will therefore be more volatile than other fixed income securities with shorter maturities. Conversely, fixed income securities with shorter maturities will be less volatile but generally provide lower potential returns than fixed income securities with longer maturities. The average maturity of the Fund's investments will affect the volatility of the Fund's share price.

Non-U.S. Government Obligation Risk. An investment in debt obligations of non-U.S. governments and their political subdivisions involves special risks that are not present in corporate debt obligations. The non-U.S. issuer of the sovereign debt or the non-U.S. governmental authorities that control the repayment of the debt may be unable or unwilling to repay principal or interest when due, and the Fund may have limited recourse in the event of a default. During periods of economic uncertainty, the market prices of sovereign debt may be more volatile than prices of debt obligations of U.S. issuers. See "Risk Factors — Fund Risks — Non-U.S. Government Obligation Risk."

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

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

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

the securities the Fund holds, and may adversely affect the Fund's investments and operations. The transmission of this coronavirus and efforts to contain its spread have resulted in travel restrictions and disruptions, closed international borders, enhanced health screenings at ports of entry and elsewhere, disruption of and delays in healthcare service preparation and delivery, quarantines, event and service cancellations or interruptions, disruptions to business operations (including staff furloughs and reductions) and supply chains, and a reduction in consumer and business spending, as well as general concern and uncertainty that has negatively affected the economy. These disruptions have led to instability in the market place, including equity and debt market losses and overall volatility, and the jobs market. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general in ways that cannot necessarily be foreseen at the present time. In addition, the impact of infectious diseases in developing or emerging market countries may be greater due to less established health care systems. Health crises caused by the recent coronavirus outbreak may exacerbate other pre-existing political, social and economic risks in certain countries. The impact of the outbreak may be short term or may last for an extended period of time.

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

In June 2016, the United Kingdom approved a referendum to leave the European Union ("EU") ("Brexit"). On March 29, 2017, the United Kingdom formally notified the European Council of its intention to leave the EU and commenced the formal process of withdrawing from the EU. The withdrawal agreement entered into between the United Kingdom and the EU entered into force on January 31, 2020, at which time the United Kingdom ceased to be a member of the EU. Following the withdrawal, there was an eleven-month transition period, ending December 31, 2020, during which the United Kingdom negotiated its future relationship with the EU. On January 1, 2021, the EU UK Trade and Cooperation Agreement, a bilateral trade and cooperation deal governing the future relationship between the UK and the EU, provisionally went into effect. The UK Parliament has already ratified the agreement, and the EU Parliament has until February 28, 2021 to do the same. Brexit has resulted in volatility in European and global markets and could have negative long-term impacts on financial markets in the United Kingdom and throughout Europe. There is considerable uncertainty about the potential consequences for Brexit, how it will be conducted, the EU UK Trade and Cooperation Agreement, how future negotiations of trade relations will proceed, and how the financial markets will react to all of the preceding, and as this process unfolds, markets may be further disrupted. Given the size and importance of the United Kingdom's economy, uncertainty about its legal, political, and economic relationship with the remaining member states of the EU may continue to be a source of instability. Moreover, other countries may seek to withdraw from the European Union and/or abandon the euro, the common currency of the EU.

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

Russian currency, a downgrade in the country's credit rating, and a decline in the value and liquidity of Russian securities. Such actions could result in a freeze of Russian securities, impairing the ability of a fund to buy, sell, receive, or deliver those securities. Retaliatory action by the Russian government could involve the seizure of US and/or European residents' assets, and any such actions are likely to impair the value and liquidity of such assets. Any or all of these potential results could have an adverse/recessionary effect on Russia's economy. All of these factors could have a negative effect on the performance of funds that have significant exposure to Russia.

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

REIT Risk. Investing in real estate investment trusts ("REITs") involves certain unique risks in addition to those risks associated with investing in the real estate industry in general. An equity REIT may be affected by changes in the value of the underlying properties owned by the REIT. A mortgage REIT may be affected by changes in interest rates and the ability of the issuers of its portfolio mortgages to repay their obligations. REITs are dependent upon the skills of their managers and are not diversified.

REITs are generally dependent upon maintaining cash flows to repay borrowings and to make distributions to shareholders and are subject to the risk of default by lessees or borrowers. REITs whose underlying assets are concentrated in properties used by a particular industry, such as health care, are also subject to risks associated with such industry. REITs (especially mortgage REITs) are also subject to interest rate risks. When interest rates decline, the value of a REIT's investment in fixed rate obligations can be expected to rise. Conversely, when interest rates rise, the value of a REIT's investment in fixed rate obligations can be expected to decline. If the REIT invests in adjustable rate mortgage loans the interest rates on which are reset periodically, yields on a REIT's investments in such loans will gradually align themselves to reflect changes in market interest rates. This causes the value of such investments to fluctuate less dramatically in response to interest rate fluctuations than would investments in fixed rate obligations. REITs may have limited financial resources, may utilize significant amounts of leverage, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities.

Historically, REITs have been more volatile in price than the larger capitalization stocks included in Standard & Poor's 500 Stock Index. See "Risk Factors — Fund Risks — REIT Risk."

Risks Associated with Options. There are several risks associated with transactions in options. For example, there are significant differences between the securities markets and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. A decision as to whether, when and how to use options involves the exercise of skill and judgment, and even a well-conceived transaction may be unsuccessful to some degree because of market behavior or unexpected events. The Fund's ability to utilize options successfully will depend on Calamos' ability to predict pertinent market movements, which cannot be assured.

The Fund may sell options on individual securities and securities indices. All call options sold by the Fund must be "covered." Even though the Fund will receive the option premium to help protect it against loss, a call option sold by the Fund exposes the Fund during the term of the option to possible loss of opportunity to realize appreciation in the market price of the underlying security or instrument and may require the Fund to hold a security or instrument that it might otherwise have sold. In addition, a loss on a call option sold may be greater than the premium received. The Fund may purchase and sell put options on individual securities and securities

indices. In selling put options, there is a risk that the Fund may be required to buy the underlying security at a disadvantageous price above the market price. The Fund may purchase and sell put options on individual securities and securities indices. In selling put options, there is a risk that the Fund may be required to buy the underlying security at a disadvantageous price above the market price. See "Risk Factors — Fund Risks — Risks Associated with Options."

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

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.

Tax Risk. The Fund may invest in certain securities, such as certain convertible securities and high yield securities, for which the federal income tax treatment may not be clear or may be subject to re-characterization by the Internal Revenue Service ("IRS"). It could be more difficult for the Fund to comply with certain federal income tax requirements applicable to regulated investment companies if the tax characterization of the Fund's investments is not clear or if the tax treatment of the income from such investments was successfully challenged by the IRS. In addition, the tax treatment of the Fund may be affected by future interpretations of the Internal Revenue Code of 1986, as amended (the "Code"), and changes in the tax laws and regulations, all of which may apply with retroactive effect. See "Risk Factors — Fund Risks — Tax Risk" and "Certain Federal Income Tax Matters."

U.S. Government Security Risk. Some securities issued by U.S. Government agencies or government sponsored enterprises are not backed by the full faith and credit of the U.S. and may only be supported by the right of the agency or enterprise to borrow from the U.S. Treasury. There can be no assurance that the U.S. Government will always provide financial support to those agencies or enterprises.

Additional Risks to Common Shareholders

Additional risks of investing in common shares include the following:

Diminished Voting Power and Excess Cash Risk. The voting power of current shareholders will be diluted to the extent that such shareholders do not purchase shares in any future common share offerings or do not purchase sufficient shares to maintain their percentage interest. In addition, if the Fund is unable to invest the proceeds of such offering as intended, its per share distribution may decrease (or may consist of return of capital) and the

Fund may not participate in market advances to the same extent as if such proceeds were fully invested as planned.

Interest Rate Transactions Risk. The Fund may enter into an interest rate swap, cap or floor transaction to attempt to protect itself from increasing dividend or interest expenses on its leverage resulting from increasing short-term interest rates and to hedge its portfolio securities. A decline in interest rates may result in a decline in the value of the swap or cap, which may result in a decline in the net asset value of the Fund. See "Risk Factors — Interest Rate Transactions Risk."

Market Discount Risk. The Fund's common shares have traded both at a premium and at a discount relative to net asset value. Common shares of closed-end investment companies frequently trade at prices lower than their net asset value. Depending on the premium of the Fund's common shares, the Fund's net asset value may be reduced immediately following an offering of the Fund's common shares by the offering expenses paid by the Fund. See "Use of Proceeds."

In addition to net asset value, the market price of the Fund's common shares may be affected by such factors as the Fund's use of leverage, dividend stability, portfolio credit quality, liquidity, market supply and demand of the common shares and the Fund's dividends paid (which are, in turn, affected by expenses), call protection for portfolio securities and interest rate movements. See "Leverage," "Risk Factors" and "Description of Securities." The Fund's common shares are designed primarily for long-term investors, and you should not purchase common shares if you intend to sell them shortly after purchase.

Whether shareholders will realize a gain or loss upon the sale of the Fund's common shares depends upon whether the market value of the shares at the time of sale is above or below the price the shareholder paid, taking into account transaction costs for the shares, and is not directly dependent upon the Fund's net asset value. Because the market value of the Fund's common shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors beyond the control of the Fund, the Fund cannot predict whether its common shares will trade at, below or above the Fund's net asset value, or below or above the public offering price for the common shares.

Market Impact Risk. The sale of our common shares (or the perception that such sales may occur) may have an adverse effect on prices in the secondary market for our common shares. An increase in the number of common shares available may put downward pressure on the market price for our common shares. These sales also might make it more difficult for us to sell additional equity securities in the future at a time and price the Fund deems appropriate.

Reduction of Leverage Risk. We have previously taken, and may in the future take, action to reduce the amount of leverage employed by the Fund. Reduction of the leverage employed by the Fund, including by redemption of preferred shares, will in turn reduce the amount of assets available for investment in portfolio securities. This reduction in leverage may negatively impact our financial performance, including our ability to sustain current levels of distributions on common shares.

See "Risk Factors — Additional Risks to Common Shareholders" for a more detailed discussion of these risks.

Additional Risks to Senior Security Holders

Additional risks of investing in senior securities include the following:

Generally, an investment in preferred shares (including exchange-listed preferred shares) or debt securities (collectively, "senior securities") is subject to the following risks:

Decline in Net Asset Value Risk. A material decline in the Fund's NAV may impair our ability to maintain required levels of asset coverage for outstanding borrowings or any debt securities or preferred shares.

Early Redemption Risk. The Fund may voluntarily redeem preferred shares or may be forced to redeem preferred shares to meet regulatory requirements and the asset coverage requirements of the preferred shares. Such redemptions may be at a time that is unfavorable to holders of the preferred shares.

Inflation Risk. Inflation is the reduction in the purchasing power of money resulting from an increase in the price of goods and services. Inflation risk is the risk that the inflation adjusted or "real" value of an investment in preferred stock or debt securities or the income from that investment will be worth less in the future. As inflation occurs, the real value of the preferred stock or debt securities and the dividend payable to holders of preferred stock or interest payable to holders of debt securities declines.

Interest Rate Risk. Rising market interest rates could impact negatively the value of our investment portfolio, reducing the amount of assets serving as asset coverage for the senior securities. Rising market interest rates could also reduce the value of the Fund's senior securities.

Market Discount Risk. The market price of exchange-listed preferred shares that the Fund may issue may also be affected by such factors as the Fund's use of leverage, dividend stability, portfolio credit quality, liquidity, and the Fund's dividends paid (which are, in turn, affected by expenses), call protection for portfolio securities and interest rate movements.

Ratings and Asset Coverage Risk. To the extent that senior securities are rated, a rating does not eliminate or necessarily mitigate the risks of investing in our senior securities, and a rating may not fully or accurately reflect all of the credit and market risks associated with that senior security. A rating agency could downgrade the rating of our shares of preferred stock or debt securities, which may make such securities less liquid in the secondary market, though potentially with higher resulting interest rates. If a rating agency downgrades the rating assigned to a senior security, we may alter our portfolio or redeem the senior security. We may voluntarily redeem senior securities under certain circumstances.

Secondary Market Risk. The market value of exchange-listed preferred shares that the Fund may issue will be determined by factors such as the relative demand for and supply of the preferred shares in the market, general market conditions and other factors beyond the control of the Fund. It may be difficult to predict the trading patterns of preferred shares, including the effective costs of trading. There is a risk that the market for preferred shares may be thinly traded and relatively illiquid compared to the market for other types of securities.

Senior Leverage Risk. Preferred shares will be junior in liquidation and with respect to distribution rights to debt securities and any other borrowings. Senior securities representing indebtedness may constitute a substantial lien and burden on preferred shares by reason of their prior claim against our income and against our net assets in liquidation. We may not be permitted to declare dividends or other distributions with respect to any series of preferred shares unless at such time we meet applicable asset coverage requirements and the payment of principal or interest is not in default with respect to any borrowings.

See "Risk Factors — Additional Risks to Senior Security Holders" for a more detailed discussion of these risks.

SUMMARY OF FUND EXPENSES

The following table and example contain information about the costs and expenses that common shareholders will bear directly or indirectly. In accordance with Commission requirements, the table below shows our expenses, including interest payments on borrowed funds, and preferred stock dividend payments, as a percentage of our average net assets as of January 31, 2021, and not as a percentage of gross assets or managed assets.

By showing expenses as a percentage of average net assets, expenses are not expressed as a percentage of all of the assets we invest. The table and example are based on our capital structure as of January 31, 2021. As of January 31, 2021, the Fund had utilized $372.4 million of the $430 million available under the SSB Agreement ($29.9 million of borrowings outstanding, and $342.5 million in structural leverage consisting of collateral received from SSB in connection with securities on loan), representing 24.2% of the Fund's managed assets as of that date, and had $100 million of MRP Shares outstanding, representing 6.5% of the Fund's managed assets. Combined, the borrowings under the SSB Agreement and the outstanding MRP Shares represented 30.6% of the Fund's managed assets.

Shareholder Transaction Expenses
Sales Load (as a percentage of offering price)		—	⁽¹⁾
Offering Expenses Borne by the Fund (as a percentage of offering price)		—	⁽¹⁾
Dividend Reinvestment Plan Fees (per sales transaction fee)⁽²⁾	$	15.00
Annual Expenses	Percentage of Average Net Assets Attributable to Common Shareholders
Management Fee⁽³⁾		1.12	%
Interest Payments on Borrowed Funds⁽⁴⁾		0.17	%
Preferred Stock Dividend Payments⁽⁵⁾		0.41	%
Other Expenses⁽⁶⁾		0.07	%
Total Annual Expenses		1.77	%

Example:

The following example illustrates the expenses that common shareholders would pay on a $1,000 investment in common shares, assuming (1) total annual expenses of 1.77% of net assets attributable to common shareholders; (2) a 5% annual return; and (3) all distributions are reinvested at net asset value:

				1 Year				3 Years				5 Years				10 Years
Total Expenses Paid by Common Shareholders⁽⁷⁾ .				$	18			$	56			$	96			$	208

The example should not be considered a representation of future expenses. Actual expenses may be greater or less than those assumed. Moreover, our actual rate of return may be greater or less than the hypothetical 5% return shown in the example.

(1) If the securities to which this prospectus relates are sold to or through underwriters, the prospectus supplement will set forth any applicable sales load and the estimated offering expenses borne by us.

(2) Shareholders will pay a $15.00 transaction fee plus a $0.02 per share brokerage charge if they direct the Plan Agent (as defined below) to sell common shares held in a Plan account. In addition, each participant will pay a pro rata share of brokerage commissions incurred with respect to the Plan Agent's open-market purchases in connection with the reinvestment of dividends or distributions. If a participant elects to have the Plan

Agent sell part or all of his or her common shares and remit the proceeds, such participant will be charged his or her pro rata share of brokerage commissions on the shares sold. See "Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan."

(3) The Fund pays Calamos an annual management fee, payable monthly in arrears, for its investment management services in an amount equal to 0.80% of the Fund's average weekly managed assets. In accordance with the requirements of the Commission, the table above shows the Fund's management fee as a percentage of average net assets attributable to common shareholders. By showing the management fee as a percentage of net assets, the management fee is not expressed as a percentage of all of the assets the Fund intends to invest. For purposes of the table, the management fee has been converted to 1.12% of the Fund's average weekly net assets as of January 31, 2021 by dividing the total dollar amount of the management fee by the Fund's average weekly net assets (managed assets less outstanding leverage).

(4) Reflects interest expense paid on $49.5 million in average borrowings under the SSB Agreement, plus $262.3 million in additional average structural leverage related to certain securities lending programs, as described under "Leverage."

(5) Reflects estimated dividend expense on $100 million aggregate liquidation preference of mandatory redeemable preferred shares outstanding. See "Leverage."

(6) "Other Expenses" are based on estimated amounts for the Fund's current fiscal year.

(7) The example does not include sales load or estimated offering costs, which would cause the expenses shown in the example to increase. In connection with an offering of common shares, the applicable prospectus supplement will set forth an example including sales load and estimated offering costs.

The purpose of the table and the example above is to help investors understand the fees and expenses that they, as common shareholders, would bear directly or indirectly. For additional information with respect to our expenses, see "Management of the Fund."

FINANCIAL HIGHLIGHTS

The information in the table below for the fiscal years ended October 31, 2020, 2019, 2018, 2017 and 2016 is derived from the Fund's financial statements for the fiscal year ended October 31, 2020 audited by Deloitte & Touche LLP, whose report on such financial statements is contained in the Fund's October 31, 2020 Annual Report and is incorporated by reference into the Statement of Additional Information. The information in the table below for the fiscal years ended October 31, 2015, 2014, 2013, 2012 and 2011 is derived from the Fund's financial statements for the fiscal year ended October 31, 2015.

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

	2020			2019			2018			2017			2016			2015			2014			2013			2012			2011
PER SHARE OPERATING PERFORMANCE
Net asset value, beginning of year	$	10.64		$	10.46		$	11.35		$	10.73		$	11.68		$	13.45		$	13.20		$	12.45		$	12.31		$	12.84
Income from investment operations:
Net investment income (loss)*		0.49			0.50			0.57			0.57			0.60			0.62			0.72			0.75			0.81			0.83
Net realized and unrealized gain (loss)		2.37			0.64			(0.33	)		1.19			(0.41	)		(1.25	)		0.67			1.14			0.47			(0.23	)
Total from investment operations		2.86			1.14			0.24			1.76			0.19			(0.63	)		1.39			1.89			1.28			0.60
Less distributions to common shareholders from:
Net investment income		(0.44	)		(0.48	)		(1.13	)		(0.67	)		(0.59	)		(0.81	)		(0.95	)		(1.14	)		(1.14	)		(0.84	)
Net realized gains		(0.52	)		(0.31	)		—			(0.08	)		—			(0.02	)		(0.19	)		—			—			—
Return of capital		—			(0.17	)		—			(0.39	)		(0.55	)		(0.31	)		—			—			—			(0.30	)
Total distributions		(0.96	)		(0.96	)		(1.13	)		(1.14	)		(1.14	)		(1.14	)		(1.14	)		(1.14	)		(1.144	)		(1.14	)
Net asset value, end of year	$	12.54		$	10.64		$	10.46		$	11.35		$	10.73		$	11.68		$	13.45		$	13.20		$	12.45		$	12.31
Market value, end of year	$	10.89		$	10.67		$	9.91		$	11.59		$	9.89		$	10.41		$	13.69		$	13.09		$	12.51		$	12.09
TOTAL RETURN APPLICABLE TO COMMON SHAREHOLDERS
Total investment return based on:^(b)
Net asset value		29.38	%		11.75	%		1.81	%		17.48	%		3.19	%		(4.69	)%		10.90	%		16.08	%		11.05	%		4.92	%
Market value		12.04	%		18.29	%		(5.54	)%		30.15	%		6.72	%		(16.54	)%		13.83	%		14.56	%		13.62	%		1.08	%
RATIOS TO AVERAGE NET ASSETS APPLICABLE TO COMMON SHAREHOLDERS
Net expenses^(c)		2.20	%		2.88	%		2.52	%		1.88	%		1.74	%		1.84	%		1.47	%		1.49	%		1.57	%		1.55	%
Net investment income (loss)		4.36	%		4.77	%		5.11	%		5.17	%		5.61	%		4.90	%		5.38	%		5.92	%		6.60	%		6.56	%
SUPPLEMENTAL DATA
Net assets applicable to common shareholders, end of year (000)	$	889,577		$	754,310		$	741,306		$	797,968		$	750,773		$	817,491		$	931,703		$	891,350		$	840,737		$	827,339
Portfolio turnover rate		76	%		51	%		58	%		90	%		34	%		36	%		40	%		62	%		56	%		44	%
Average commission rate paid	$	0.0213		$	0.0188		$	0.0270		$	0.0282		$	0.0220		$	0.0303		$	0.0294		$	0.0295		$	0.0230		$	0.0222
Capital charge resulting from issuance of common and preferred shares and related offering costs		—		$	—		$	—		$	—		$	—		$	—		$	—	^(a)	$	—	^(a)	$	—	^(a)	$	—	^(a)
Premiums from shares sold in at the market offerings		—		$	—		$	—	^(a)	$	—	^(a)	$	—		$	—	^(a)	$	—	^(a)	$	—		$	—	^(a)	$	0.01
Mandatory Redeemable Preferred Shares, at redemption value ($25 per share liquidation preference) (000's omitted)	$	100,000		$	100,000		$	100,000		$	100,000		$	—		$	—		$	—		$	—		$	—		$	—
Notes Payable (000's omitted)	$	288,400		$	277,400		$	288,000		$	275,000		$	306,000		$	353,000		$	360,000		$	350,000		$	285,000		$	285,000
Asset coverage per $1,000 of loan outstanding^(d)	$	4,431		$	4,080		$	3,921		$	4,265		$	3,454		$	3,316		$	3,588		$	3,547		$	3,950		$	3,903
Asset coverage per $25 liquidation value per share of Mandatory Redeemable Preferred Shares^(e)	$	319		$	283		$	282		$	293		$	—		$	—		$	—		$	—		$	—		$	—

* Net investment income calculated based on average shares method.

(a) Amount equated to less than $0.005 per common share.

(b) Total investment return is calculated assuming a purchase of common stock on the opening of the first day and a sale on the closing of the last day of the period reported. Dividends and distributions are assumed, for purposes of this calculation, to be reinvested at prices obtained under the Fund's dividend reinvestment plan. Total return is not annualized for periods less than one year. Brokerage commissions are not reflected. NAV per share is determined by dividing the value of the Fund's portfolio securities, cash and other assets, less all liabilities, by the total number of common shares outstanding. The common share market price is the price the market is willing to pay for shares of the Fund at a given time. Common share market price is influenced by a range of factors, including supply and demand and market conditions.

(c) Ratio of net expenses, excluding interest expense on Notes Payable and interest expense and amortization of offering costs on Mandatory Redeemable Preferred Shares, to average net assets was 1.26%, 1.29%, 1.28%, 1.24%, 1.24%, 1.50%, 1.18%, 1.17%, 1.17%, and 1.19%, respectively.

(d) Does not reflect the effect of dividend payments to Auction Rate Preferred Shareholders.

(e) Calculated by subtracting the Fund's total liabilities (not including Notes payable and Mandatory Redeemable Preferred Shares) from the Fund's total assets and dividing this by the amount of notes payable outstanding, and by multiplying the result by 1,000.

(f) Calculated by subtracting the Fund's total liabilities (not including Notes payable and Mandatory Redeemable Preferred Shares) from the Fund's total assets and dividing this by the amount of Mandatory Redeemable Preferred Shares outstanding, and by multiplying the result by 25.

The following table sets forth information regarding the Fund's outstanding bank loans and MRP Shares as of the end of each of the Fund's last ten fiscal years, as applicable. The information in the table shown below comes from the Fund's financial statements for the fiscal year ended October 31, 2020, and each of the prior nine years then ended, all of which have been audited by Deloitte & Touche LLP, the Fund's independent registered public accounting firm.

Fiscal Year Ended	Total Amount Outstanding		Asset Coverage			Liquidating Preference per Preferred Share^(c)		Average Market Value per Preferred Share			Type of Senior Security
October 31, 2020	$	288,400,000		4,431	^(a)		—		—		Loan
October 31, 2020	$	100,000,000		319	^(b)		25		25	^(d)	MRPS
October 31, 2019	$	277,400,000		4,080	^(a)		—		—		Loan
October 31, 2019	$	100,000,000		283	^(b)		25		25	^(d)	MRPS
October 31, 2018	$	288,000,000		3,921	^(a)		—		—		Loan
October 31, 2018	$	100,000,000		282	^(b)		25		25	^(d)	MRPS
October 31, 2017	$	275,000,000		4,265	^(a)		—		—		Loan
October 31, 2017	$	100,000,000		293	^(b)		25		25	^(d)	MRPS
October 31, 2016	$	306,000,000		3,454	^(a)		—		—		Loan
October 31, 2015	$	353,000,000		3,316	^(a)		—		—		Loan
October 31, 2014	$	360,000,000		3,588	^(a)		—		—		Loan
October 31, 2013	$	350,000,000		3,547	^(a)		—		—		Loan
October 31, 2012	$	285,000,000		3,950	^(a)		—		—		Loan
October 31, 2011	$	285,000,000		3,903	^(a)		—		—		Loan

(a) Calculated by subtracting the Fund's total liabilities (not including notes payable and MRPS) from the Fund's total assets and dividing this by the amount of notes payable outstanding, and by multiplying the result by 1,000.

(b) Calculated by subtracting the Fund's total liabilities (not including MRPS) from the Fund's total assets and dividing this by the number of MRPS outstanding, and by multiplying the result by 25.

(c) "Liquidating Preference per Preferred Share" means the amount to which a holder of preferred shares would be entitled upon the liquidation of the Fund in preference to common shareholders, expressed as a dollar amount per preferred share.

(d) The MRPS are not listed on any exchange or automated quotation system. The MRPS are considered debt of the issuer; and the liquidation preference approximates fair value.

MARKET AND NET ASSET VALUE INFORMATION

Our common shares are listed on the Nasdaq Global Select Market ("Nasdaq") under the symbol "CHI." Our common shares commenced trading on the New York Stock Exchange ("NYSE") in June 2002. On July 2, 2012, the common shares ceased trading on the NYSE and commenced trading on Nasdaq.

Our common shares have traded both at a premium and a discount to NAV. We cannot predict whether our shares will trade in the future at a premium or discount to NAV. The provisions of the 1940 Act generally require that the public offering price of common shares (less any underwriting commissions and discounts) must equal or exceed the NAV per share of a company's common stock (calculated within 48 hours of pricing). Our issuance of common shares may have an adverse effect on prices in the secondary market for our common shares by increasing the number of common shares available, which may put downward pressure on the market price for our common shares. Shares of common stock of closed-end investment companies frequently trade at a discount from NAV. See "Risk Factors — Additional Risks to Common Shareholders — Market Discount Risk."

The following table sets forth for each of the periods indicated the high and low closing market prices for our common shares on Nasdaq, the NAV per share and the premium or discount to NAV per share at which our common shares were trading. NAV is shown for the last business day of each quarter. See "Net Asset Value" for information as to the determination of our NAV.

	Market Price⁽¹⁾				Net Asset Value at Quarter		Premium/ (Discount) to Net Asset Value⁽³⁾
Quarter Ended	High		Low		End⁽²⁾		High			Low
January 31, 2019	$	10.49	$	8.30	$	10.45		(2.15	)%		(12.54	)%
April 30, 2019	$	10.67	$	10.00	$	10.90		(2.11	)%		(5.39	)%
July 31, 2019	$	10.83	$	9.84	$	10.95		(1.99	)%		(4.19	)%
October 31, 2019	$	10.72	$	10.23	$	10.64		(1.65	)%		(2.57	)%
January 31, 2020	$	11.33	$	10.65	$	11.30		(1.48	)%		(0.84	)%
April 30, 2020	$	11.72	$	5.85	$	9.86		(0.85	)%		(25.86	)%
July 31, 2020	$	11.08	$	8.78	$	12.35		(10.28	)%		(8.83	)%
October 31, 2020	$	11.95	$	10.76	$	12.54		(9.19	)%		(12.73	)%
January 31, 2021	$	14.13	$	10.97	$	15.07		(9.19	)%		(12.97	)%

Source: Bloomberg Financial and Fund Accounting Records.

(1) Based on high and low closing market price per share during the respective quarter and does not reflect commissions.

(2) Based on the NAV calculated on the close of business on the last business day of each calendar quarter.

(3) Premium and discount information is shown for the days when the Fund experienced its high and low closing market prices, respectively, per share during the respective quarter.

The last reported sale price, NAV per common share and percentage discount to NAV per common share on January 31, 2021 were $13.53, $15.07 and (10.22)%, respectively. As of January 31, 2021, we had 70,923,815 common shares outstanding and managed assets of $1.5 billion.

USE OF PROCEEDS

Subject to the remainder of this section, and unless otherwise specified in a prospectus supplement, we currently intend to invest the net proceeds of any sales of our securities pursuant to this prospectus in accordance with our investment objective and policies as described under "Investment Objective and Principal Investment Strategies" within approximately three months of receipt of such proceeds. Such investments may be delayed if suitable investments are unavailable at the time or for other reasons. Pending such investment, we anticipate that we will invest the proceeds in securities issued by the U.S. government or its agencies or instrumentalities or in high quality, short-term or long-term debt obligations. We may also use proceeds from the sale of our securities to (i) retire all or a portion of any short-term debt we incur in pursuit of our investment objective and policies and (ii) for working capital purposes, including the payment of interest and operating expenses, although there is currently no intent to issue securities primarily for these purposes. A delay in the anticipated use of proceeds could lower returns, reduce our distribution to common shareholders and reduce the amount of cash available to make dividend and interest payments on preferred shares and debt securities, respectively.

THE FUND

Calamos Convertible Opportunities and Income Fund is a diversified, closed-end management investment company which commenced investment operations in June 2002. The Fund was organized as a statutory trust under the laws of the State of Delaware on April 17, 2002, and has registered under the 1940 Act. On June 28, 2002, the Fund issued an aggregate of 40,000,000 common shares, no par value, in an initial public offering and commenced its operations. On July 12, 2002 and August 13, 2002, the Fund issued an additional 3,000,000 and 225,000 common shares, respectively, in connection with exercises by the underwriters of their over-allotment option. The net proceeds of the initial public offering and subsequent exercises of the over-allotment option were approximately $619,298,400 after the payment of offering expenses. As of January 31, 2019, the Fund had issued an additional 19,077,463 common shares in connection with a continuous, at-the-market offering that commenced in June 2008 and ceased in December 2017 (the "Previous ATM Offering"). The net proceeds of the Previous ATM Offering were $228,615,606. As of January 31, 2021, the Fund had not issued additional common shares in connection with a continuous, at-the-market offering that commenced on March 8, 2019.

As of January 31, 2021, the Fund had utilized $372.4 million of the $430 million available under the SSB Agreement ($29.9 million of borrowings outstanding, and $342.5 million in structural leverage consisting of collateral received from SSB in connection with securities on loan), representing 24.2% of the Fund's managed assets as of that date, and had $100 million of MRP Shares outstanding, representing 6.5% of the Fund's managed assets. Combined, the borrowings under the SSB Agreement and the outstanding MRP Shares represented 30.6% of the Fund's managed assets. Structural leverage refers to borrowings under the SSB Agreement in respect of which the Fund's interest payments are reduced or eliminated by the Fund's securities lending activities. See "Leverage." The Fund's common shares are listed on Nasdaq under the symbol "CHI." The Fund's principal office is located at 2020 Calamos Court, Naperville, Illinois 60563, and its telephone number is 800-582-6959.

The following table provides information about our outstanding securities as of January 31, 2021:

Title of Class	Amount Authorized (shares)		Amount Held by the Fund or for its Account		Amount Outstanding (shares)
Common Shares		Unlimited		0		70,923,815
MRPS-Series A		1,330,000		0		1,330,000
MRPS-Series B		1,330,000		0		1,330,000
MRPS-Series C		1,340,000		0		1,340,000

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

Investment Objective

The Fund's investment objective is to provide total return through a combination of capital appreciation and current income. The Fund's investment objective may be changed by the Board of Trustees without a shareholder vote, although the Fund will give shareholders at least 60 days' written notice of any change to the Fund's investment objective. The Fund makes no assurance that it will realize its objective. An investment in the Fund may be speculative in that it involves a high degree of risk and should not constitute a complete investment program. See "Risk Factors."

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its managed assets in a diversified portfolio of convertible securities and non-convertible income securities. This is a non-fundamental policy and may be changed by the Board of Trustees of the Fund provided that shareholders are provided with at least 60 days' prior written notice of any change as required by the rules under the 1940 Act. The portion of the Fund's assets invested in convertible securities and non-convertible income securities will vary from time to time consistent with the Fund's investment objective, changes in equity prices and changes in interest rates and other economic and market factors, although, under normal circumstances, the Fund will invest at least 35% of its managed assets in convertible securities. The Fund invests in securities with a broad range of maturities. The average term to maturity of the Fund's securities typically will range from five to ten years.

Convertible Securities. The Fund is not limited in the percentage of its assets invested in convertible securities, and investment in convertible securities forms an important part of the Fund's principal investment strategies. Under normal circumstances, the Fund will invest at least 35% of its managed assets in convertible securities. A convertible security is a debt security, debenture, note or preferred stock that may be converted into an equity security (typically common stock of the same issuer) at a predetermined price (the "conversion price"). Depending upon the relationship of the conversion price to the market value of the underlying security, a convertible security may trade more like an equity security than a debt instrument. The Fund may invest in convertible securities of any rating.

Calamos typically applies a four-step approach when buying and selling convertible securities for the Fund, which includes:

1. Evaluating the default risk of the convertible security using traditional credit analysis;

2. Analyzing the convertible's underlying common stock to determine its capital appreciation potential;

3. Assessing the risk/return potential of the convertible security; and

4. Evaluating the convertible security's impact on the overall composition of the Fund and its diversification strategy.

In analyzing the appreciation potential of the underlying common stock and the default risk of the convertible security, Calamos generally considers the issuer's:

• financial soundness;

• ability to make interest and dividend payments;

• earnings and cash-flow forecast; and

• quality of management.

simulate the economic characteristics of another instrument (i.e., a convertible security) through the combined economic features of a collection of other securities or assets. Calamos may create a synthetic convertible instrument by combining separate securities that possess the two principal characteristics of a true convertible security, i.e., a fixed-income security ("fixed-income component", which may be a convertible or non-convertible security) and the right to acquire an equity security ("convertible component"). The fixed-income component is achieved by investing in fixed-income securities such as bonds, preferred stocks and money market instruments. The convertible component is achieved by investing in warrants or options to buy common stock at a certain exercise price, or options on a stock index.

Some examples of these securities include the following:

Preferred equity redeemable cumulative stock ("PERCS") are shares that automatically convert into one ordinary share upon maturity. They are usually issued at the prevailing share price, convertible into one ordinary share, with an enhanced dividend yield. PERCS pay a higher dividend than common shares, but the equity appreciation is capped. Above a certain share price, the conversion ratio will fall as the stock rises, capping the appreciation at that level. Below this level, the conversion ratio remains one-for-one, giving the same downside exposure as the ordinary shares, excluding the income difference.

Dividend enhanced convertible stock ("DECS") are either preference shares or subordinated bonds. These, like PERCS, mandatorily convert into ordinary shares at maturity, if not already converted. DECS give no significant loss protection and involve a risk of loss comparable to investing directly in equity securities, with lower relative direct bond characteristics and interest rate exposure. As with PERCS, some of the appreciation potential is capped and in return, the investor receives an enhanced potential yield. Unlike PERCS, however, the investor's appreciation potential is not capped. Instead, the investor limits its ability to participate in appreciation within a range of prices.

Preferred Redeemable Increased Dividend Equity Security ("PRIDES") are synthetic securities consisting of a forward contract to purchase the issuer's underlying security and an interest bearing deposit. Interest payments are made at regular intervals, and conversion into the underlying security is mandatory at maturity. Similar to convertible securities, PRIDES allow investors the potential to earn stable cash flows while still participating in the appreciation of an underlying stock.

The Fund may also purchase convertible structured notes. Convertible structured notes are fixed income debentures linked to equity. Convertible structured notes have the attributes of a convertible security; however, the investment bank that issued the convertible note assumes the credit risk associated with the investment, rather than the issuer of the underlying common stock into which the note is convertible. Different companies may issue the fixed-income and convertible components, which may be purchased separately and at different times. The Fund remains subject to the credit risk of the issuing investment bank.

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

High Yield Securities. A substantial portion of the Fund's assets may be invested in below investment grade (high yield, high risk) securities for either current income or capital appreciation or both. These securities are rated Ba or lower by Moody's or BB or lower by Standard & Poor's or are unrated securities of comparable quality as determined by Calamos, the Fund's investment adviser. The Fund may invest in high yield securities of any rating. The Fund may, but currently does not intend to, invest up to 5% of its managed assets in distressed securities that are in default or the issuers of which are in bankruptcy. Non-convertible debt securities rated below investment grade are commonly referred to as "junk bonds" and are considered speculative with respect to the issuer's capacity to pay interest and repay principal. Below investment grade securities involve greater risk of loss, are subject to greater price volatility and are less liquid, especially during periods of economic uncertainty or change, than higher rated securities.

Foreign Securities. Although the Fund primarily invests in securities of U.S. issuers, the Fund may invest up to 25% of its net assets in securities of foreign issuers in developed and emerging markets, including debt and equity securities of corporate issuers and debt securities of government issuers. A foreign issuer is a foreign government or a company organized under the laws of a foreign country. In analyzing the foreign issuers in which the Fund may invest, Calamos will generally consider a number of factors that may characterize the issuer's economic ties to a particular foreign country or region. Such factors may include any or all of the following: the characteristics of the economy in the principal country or countries in which the issuer sells it goods and/or services; the stability of the currency in the issuer's country of organization; the laws with respect to international trade and property rights in the issuer's country of organization; and the tax, accounting and regulatory requirements of the issuer's country of organization.

Options Writing. The Fund may seek to generate income from option premiums by writing (selling) options. The Fund may write (sell) call options (i) on a portion of the equity securities (including equity securities obtainable by the Fund through the exercise of its rights with respect to convertible securities it owns) in the Fund's portfolio and (ii) on broad-based securities indices (such as the S&P 500 or MSCI EAFE) or certain ETFs (exchange traded funds) that trade like common stocks but seek to replicate such market indices.

In addition, to seek to offset some of the risk of a potential decline in value of certain long positions, the Fund may also purchase put options on individual securities, broad-based securities indices (such as the S&P 500 or MSCI EAFE), or certain ETFs that trade like common stocks but seek to replicate market indices. See " — Options in General" below.

Options in General. The Fund may purchase and sell options on stocks, indices, rates, credit spreads or currencies. A call option, upon payment of a premium, gives the purchaser of the option the right to buy, and the seller the obligation to sell, the underlying security, index or other instrument at the exercise price. A put option gives the purchaser of the option, upon payment of a premium, the right to sell, and the seller the obligation to buy, the underlying security, index, or other instrument at the exercise price.

Certain options, known as "American style" options, may be exercised at any time during the term of the option. Other options, known as "European style" options, may be exercised only on the expiration date of the option. The Fund expects that substantially all of the options written by the Fund will be American style options.

The Fund is authorized to purchase and sell exchange listed options and over-the-counter options ("OTC options"). Exchange listed options are issued by a regulated intermediary such as the Options Clearing Corporation ("OCC"), which guarantees the performance of the obligations of the parties to such options. In addition, the Fund may purchase instruments structured by broker-dealers or investment banks that package or possess economic characteristics of options. The discussion below uses the OCC as an example, but is also applicable to other financial intermediaries.

With certain exceptions, OCC issued and exchange listed options generally settle by physical delivery of the underlying security or currency, although in the future cash settlement may become available. Index options are cash settled for the net amount, if any, by which the option is "in-the-money" (i.e., where the value of the underlying instrument exceeds, in the case of a call option, or is less than, in the case of a put option, the exercise price of the option) at the time the option is exercised. Frequently, rather than taking or making delivery of the underlying instrument through the process of exercising the option, listed options are closed by entering into offsetting purchase or sale transactions that do not result in ownership of the new option.

OTC options are purchased from or sold to securities dealers, financial institutions or other parties ("Counterparties") through direct bilateral agreement with the Counterparty. In contrast to exchange listed options, which generally have standardized terms and performance mechanics, all the terms of an OTC option, including such terms as method of settlement, term, exercise price, premium, guarantees and security, are set by negotiation of the parties. The Fund may sell OTC options (other than OTC currency options) that are subject to a buy-back provision permitting the Fund to require the Counterparty to sell the option back to the Fund at a formula price within seven days. The Fund expects generally to enter into OTC options that have cash settlement provisions, although it is not required to do so. The staff of the Commission currently takes the position that OTC options purchased by a fund, and portfolio securities "covering" the amount of a fund's obligation pursuant to an OTC option sold by it (or the amount of assets equal to the formula price for the repurchase of the option, if any, less the amount by which the option is in-the-money) are illiquid. OTC options purchased by the Fund and any portfolio securities used to cover obligations pursuant to such options are not considered illiquid by Calamos for the purposes of the Fund's limitation on investments in illiquid securities.

The Fund will write call options and put options only if they are "covered." For example, a call option written by the Fund will require the Fund to hold the securities subject to the call (or securities convertible into those securities without additional consideration) or to segregate cash or liquid assets sufficient to purchase and deliver the securities if the call is exercised. A call option sold by the Fund on an index will require the Fund to own portfolio securities that correlate with the index or to segregate cash or liquid assets equal to the excess of the index value over the exercise price on a current basis. A put option written by the Fund requires the Fund to segregate cash or liquid assets equal to the exercise price.

The principal factors affecting the market value of a put or a call option include supply and demand, interest rates, the current market price of the underlying security or index in relation to the exercise price of the option, the volatility of the underlying security or index, and the time remaining until the expiration date.

Rule 144A Securities. The Fund may invest without limit in certain securities, such as convertible and debt securities, that are typically purchased in transactions exempt from the registration requirements of the 1933 Act pursuant to Rule 144A under that Act. Rule 144A Securities may only be sold to qualified institutional buyers, such as the Fund. Any resale of these securities must generally be effected through a sale that is registered under the 1933 Act or otherwise exempted or excepted from such registration requirements. Under the supervision and oversight of the Fund's Board of Trustees, Calamos will determine whether Rule 144A Securities are liquid. Typically, the Fund purchases Rule 144A Securities only if Calamos has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Loans. The Fund may invest in loan participations and other direct claims against a borrower. The corporate loans in which the Fund may invest primarily consist of direct obligations of a borrower and may include debtor in possession financings pursuant to Chapter 11 of the U.S. Bankruptcy Code, obligations of a borrower issued in connection with a restructuring pursuant to Chapter 11 of the U.S. Bankruptcy Code, leveraged buy-out loans, leveraged recapitalization loans, receivables purchase facilities, and privately placed notes. The Fund may invest in a corporate loan at origination as a co-lender or by acquiring in the secondary market participations in, assignments of or novations of a corporate loan. By purchasing a participation, the Fund acquires some or all of the interest of a bank or other lending institution in a loan to a corporate or government borrower. The participations typically will result in the Fund having a contractual relationship only with the lender not the borrower. The Fund will have the right to receive payments of principal, interest and any fees to which it is entitled only from the lender selling the participation and only upon receipt by the lender of the payments from the borrower. Many such loans are secured, although some may be unsecured. Such loans may be in default at the time of purchase. Loans that are fully secured offer the Fund more protection than an unsecured loan in the event of non-payment of scheduled interest or principal. However, there is no assurance that the liquidation of collateral from a secured loan would satisfy the corporate borrower's obligation, or that the collateral can be liquidated. Direct debt instruments may involve a risk of loss in case of default or insolvency of the borrower and may offer less legal protection to the Fund in the event of fraud or misrepresentation. In addition, loan participations involve a risk of insolvency of the lending bank or other financial intermediary. The markets in such loans are not regulated by federal securities laws or the Commission.

Preferred Shares. The Fund may invest in preferred stock. The preferred stock in which the Fund typically will invest will be convertible securities. Preferred shares are equity securities, but they have many characteristics of fixed income securities, such as a fixed dividend payment rate and/or a liquidity preference over the issuer's common shares. However, because preferred stocks are equity securities, they may be more susceptible to risks traditionally associated with equity investments than the Fund's fixed income securities.

REITs. The Fund may invest in securities of REITs, including debt securities they may issue. REITs primarily invest in income-producing real estate or real estate related loans or interests. REITs are generally classified as equity REITs, mortgage REITs or a combination of equity and mortgage REITs. Equity REITs invest the majority of their assets directly in real property and derive income primarily from the collection of rents. Equity REITs can also realize capital gains by selling properties that have appreciated in value. Mortgage REITs invest the majority of their assets in real estate mortgages and derive income from the collection of interest payments. REITs are not taxed on income distributed to shareholders provided they comply with the applicable requirements of the Code. The Fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests in addition to the expenses paid by the Fund. Debt securities issued by REITs are, for the most part, general and unsecured obligations and are subject to risks associated with REITs.

U.S. Government Securities. U.S. government securities in which the Fund invests include debt obligations of varying maturities issued by the U.S. Treasury or issued or guaranteed by an agency or instrumentality of the U.S. government, including the Federal Housing Administration, Federal Financing Bank, Farmers Home Administration, Export-Import Bank of the United States, Small Business Administration, Government National Mortgage Association ("GNMA"), General Services Administration, Central Bank for Cooperatives, Federal Farm Credit Banks, Federal Home Loan Banks, Federal Home Loan Mortgage Corporation ("FHLMC"), Federal National Mortgage Association ("FNMA"), Maritime Administration, Tennessee Valley Authority, District of Columbia Armory Board, Student Loan Marketing Association, Resolution Fund Corporation and various institutions that previously were or currently are part of the Farm Credit System (which has been undergoing reorganization since 1987). Some U.S. government securities, such as U.S. Treasury bills, Treasury notes and Treasury bonds, which differ only in their interest rates, maturities and times of issuance, are supported by the full faith and credit of the United States. Others are supported only by: (i) the right of the issuer to borrow from the U.S. Treasury, such as securities of the Federal Home Loan Banks; (ii) the discretionary authority of the U.S. government to purchase the agency's obligations, such as securities of the FNMA; or (iii) only the credit of the issuer. No assurance can be given that the U.S. government will provide financial support in the future to

U.S. government agencies, authorities or instrumentalities that are not supported by the full faith and credit of the United States. Securities guaranteed as to principal and interest by the U.S. government, its agencies, authorities or instrumentalities include: (i) securities for which the payment of principal and interest is backed by an irrevocable letter of credit issued by the U.S. government or any of its agencies, authorities or instrumentalities; and (ii) participations in loans made to non-U.S. governments or other entities that are so guaranteed. The secondary market for certain of these participations is limited and, therefore, may be regarded as illiquid.

Zero Coupon Securities. The securities in which the Fund invests may include zero coupon securities, which are debt obligations that are issued or purchased at a significant discount from face value. The discount may approximate the total amount of interest the security will accrue and compound over the period until maturity or the particular interest payment date at a rate of interest reflecting the market rate of the security at the time of issuance. Zero coupon securities do not require the periodic payment of interest. These investments benefit the issuer by mitigating its need for cash to meet debt service, but generally require a higher rate of return to attract investors who are willing to defer receipt of cash. These investments involve greater interest rate risk and may experience greater volatility in market value than U.S. government securities that make regular payments of interest. The Fund accrues income on these investments for tax and accounting purposes, which is distributable to shareholders and which, because no cash is received at the time of accrual, may require the liquidation of other portfolio securities to satisfy the Fund's distribution obligations or to reduce or eliminate tax at the Fund level, in which case the Fund will forgo the purchase of additional income producing assets with these funds. Zero coupon U.S. government securities include STRIPS and CUBES, which are issued by the U.S. Treasury as component parts of U.S. Treasury bonds and represent scheduled interest and principal payments on the bonds.

Equity Securities. Consistent with its objective, the Fund may invest in equity securities, including common and preferred stocks, warrants, rights and depository receipts. Equity securities, such as common stock, generally represent an ownership interest in a company. Therefore, the Fund participates in the financial success or failure of any company in which it has an equity interest. Although equity securities have historically generated higher average returns than fixed income securities, equity securities have also experienced significantly more volatility in those returns. An adverse event, such as an unfavorable earnings report, may depress the value of a particular equity security held by the Fund. Also, the price of equity securities, particularly common stocks, are sensitive to general changes in economic conditions and movements in the stock market. A drop in the stock market may depress the price of equity securities held by the Fund. See also " — Preferred Shares" below.

Other Investment Companies. The Fund may invest in the securities of other investment companies to the extent that such investments are consistent with the Fund's investment objective and policies and are permissible under the 1940 Act. Under the 1940 Act, the Fund may not acquire the securities of other domestic or non-U.S. investment companies if, as a result, (1) more than 10% of the Fund's total assets would be invested in securities of other investment companies, (2) such purchase would result in more than 3% of the total outstanding voting securities of any one investment company being held by the Fund, (3) more than 5% of the Fund's total assets would be invested in any one investment company, or (4) such purchase would result in more than 10% of the total outstanding voting securities of a registered closed-end investment company being held by the Fund. These limitations do not apply to, among other things, the purchase of shares of money market funds, of certain related funds or of funds with exemptive relief, or of any investment company in connection with a merger, consolidation, reorganization or acquisition of substantially all the assets of another investment company, or to purchases of investment companies made in accordance with SEC exemptive relief or rule.

The Fund, as a holder of the securities of other investment companies, will bear its pro rata portion of the other investment companies' expenses, including advisory fees. These expenses are in addition to the direct expenses of the Fund's own operations. In addition, the Fund's performance may be magnified positively or negatively by virtue of its investment in other investment companies.

Temporary and Defensive Investments. Under unusual market or economic conditions or for temporary defensive purposes, the Fund may invest in a manner that is inconsistent with its principal investment strategies

described herein. In those situations, the Fund may invest up to 100% of its managed assets in securities issued or guaranteed by the U.S. government or its instrumentalities or agencies, certificates of deposit, bankers' acceptances and other bank obligations, commercial paper rated in the highest category by a nationally recognized statistical rating organization ("NRSRO") or other fixed income securities deemed by Calamos to be consistent with a defensive posture, or may hold cash. The yield on such securities may be lower than the yield on lower rated fixed income securities. During such periods, the Fund may not be able to achieve its investment objective.

Repurchase Agreements. The Fund may enter into repurchase agreements with broker-dealers, member banks of the Federal Reserve System and other financial institutions. Repurchase agreements are arrangements under which the Fund purchases securities and the seller agrees to repurchase the securities within a specific time and at a specific price. The repurchase price is generally higher than the Fund's purchase price, with the difference being income to the Fund. The counterparty's obligations under the repurchase agreement are typically collateralized with U.S. Treasury and/or agency obligations with a market value of not less than 100% of the obligations, valued daily. Collateral is typically held by the Fund's custodian in a segregated, safekeeping account for the benefit of the Fund. Repurchase agreements afford the Fund an opportunity to earn income on temporarily available cash. In the event of commencement of bankruptcy or insolvency proceedings with respect to the issuer of the repurchase agreement before repurchase of the security under a repurchase agreement, the Fund may encounter losses and delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. If the court characterizes the transaction as a loan and the Fund has not perfected a security interest in the security, the Fund may be required to return the security to the seller's estate and be treated as an unsecured creditor of the seller. As an unsecured creditor, the Fund would be at risk of losing some or all of the principal and interest involved in the transaction.

Lending of Portfolio Securities. The Fund has authorized SSB as securities lending agent to lend securities to registered broker-dealers or other institutional investors deemed by Calamos to be of good standing under agreements which require that the loans be secured continuously by collateral received in cash under the SSB Agreement. Cash collateral held by SSB on behalf of the Fund may be credited against the amounts borrowed under the SSB Agreement, such that the Fund will effectively bear lower interest expense with respect to those borrowed amounts. Any amounts credited against borrowings under the SSB Agreement would count against the Fund's leverage limitations, unless otherwise covered in accordance with SEC Release IC-10666. Under the terms of the SSB Agreement, SSB will return the value of the collateral to the borrower at the termination of the selected securities loan(s), which will eliminate the credit against the borrowings under the SSB Agreement and will increase the balance on which the Fund will pay interest. Under the terms of the SSB Agreement, the Fund will make a variable "net income" payment related to any collateral credited against the borrowings under the SSB Agreement which will be paid to the securities borrower, less any payments due to the Fund or SSB under the terms of the SSB Agreement. The Fund does not use affiliated agents in managing its lending program. The Fund continues to be entitled to receive the equivalent of the interest or dividends paid by the issuer on the securities loaned as well as the benefit of an increase and the detriment of any decrease in the market value of the securities loaned and would also receive compensation based on investment of the collateral, but bears the risk of loss on any collateral so invested. The Fund would not, however, have the right to vote any securities having voting rights during the existence of the loan, but could seek to call the loan in anticipation of an important vote to be taken among holders of the securities or of the giving or withholding of consent on a material matter affecting the investment.

As with other extensions of credit, there are risks of delay in recovery or even loss of rights in the collateral should the borrower of the securities fail financially. The Fund remains liable for the return of the pledged collateral or cash of an equivalent value. At no time would the value of the securities loaned exceed 33 1/3% of the value of the Fund's managed assets. See "Description of Securities" for more information on lending of portfolio securities.

Portfolio Turnover. Although the Fund does not purchase securities with a view to rapid turnover, there are no limitations on the length of time that portfolio securities must be held. Portfolio turnover can occur for a number of reasons, including calls for redemption, general conditions in the securities markets, more favorable

investment opportunities in other securities, or other factors relating to the desirability of holding or changing a portfolio investment. The portfolio turnover rates may vary greatly from year to year. A high rate of portfolio turnover in the Fund would result in increased transaction expense, which must be borne by the Fund. High portfolio turnover may also result in the realization of capital gains or losses and, to the extent net short-term capital gains are realized, any distributions resulting from such gains will be considered ordinary income for federal income tax purposes.

Fundamental Investment Restrictions. As more fully described in the Fund's statement of additional information, under the Fund's fundamental investment restrictions, the Fund may not: (1) issue senior securities, except as permitted by the 1940 Act and the rules and interpretive positions of the Commission thereunder; (2) borrow money, except as permitted by the 1940 Act and the rules and interpretive positions of the Commission thereunder; (3) invest in real estate, except that the Fund may invest in securities of issuers that invest in real estate or interests therein, securities that are secured by real estate or interests therein, securities of real estate investment funds and mortgage-backed securities; (4) make loans, except by the purchase of debt obligations, by entering into repurchase agreements or through the lending of portfolio securities and as otherwise permitted by the 1940 Act and the rules and interpretive positions of the Commission thereunder; (5) invest in physical commodities or contracts relating to physical commodities; (6) act as an underwriter, except as it may be deemed to be an underwriter in a sale of securities held in its portfolio; (7) make any investment inconsistent with the Fund's classification as a diversified investment company under the 1940 Act and the rules and interpretive positions of the Commission thereunder; and (8) concentrate its investments in securities of companies in any particular industry as defined in the 1940 Act and the rules and interpretive positions of the Commission thereunder. This description of the Fund's fundamental investment restrictions is a summary only and to the extent it differs from the discussion of fundamental investment restrictions contained in the Fund's statement of additional information, the description in the statement of additional information controls.

These restrictions may not be changed without the approval of the holders of a majority of the Fund's outstanding voting securities. All other investment policies of the Fund are considered non-fundamental and may be changed by the Board of Trustees without prior approval of the Fund's outstanding voting shares, although the Fund will give shareholders at least 60 days' notice of any changes to the Fund's investment objective. See "Investment Restrictions" on page S-23 of the Fund's statement of additional information.

Conflicts of Interest

Conflicts of interest may arise from the fact that Calamos and its affiliates carry on substantial investment activities for other clients, in which the Fund does not have an interest, some of which may have investment strategies similar to those of the Fund. Calamos or its affiliates may have financial incentives to favor certain of these accounts over the Fund. Any of their proprietary accounts or other customer accounts may compete with the Fund for specific trades. Calamos or its affiliates may give advice and recommend securities to, or buy or sell securities for, other accounts and customers, which advice or securities recommended may differ from advice given to, or securities recommended or bought or sold for, the Fund, even though their investment objectives may be the same as, or similar to, the Fund's investment objective. When two or more clients advised by Calamos or its affiliates seek to purchase or sell the same publicly traded securities, the securities actually purchased or sold will be allocated among the clients on a good faith equitable basis by Calamos in its discretion and in accordance with the clients' various investment objectives and Calamos' procedures. In some cases, this system may adversely affect the price or size of the position the Fund may obtain or sell. In other cases, the Fund's ability to participate in volume transactions may produce better execution for the Fund.

Calamos will evaluate a variety of factors in determining whether a particular investment opportunity or strategy is appropriate and feasible for a particular entity or account at a particular time, including, but not limited to, the following: (1) the nature of the investment opportunity taken in the context of the other investments available at the time; (2) the liquidity of the investment relative to the needs of the particular entity or account; (3) the availability of the opportunity (i.e., size of obtainable position); (4) the transaction costs involved; and (5) the investment or regulatory limitations applicable to the particular entity or account. Because these

considerations may differ when applied to the Fund and relevant accounts under management in the context of any particular investment opportunity, the Fund's investment activities, on the one hand, and other managed accounts, on the other hand, may differ considerably from time to time. In addition, the Fund's fees and expenses will differ from those of the other managed accounts. Accordingly, investors should be aware that the Fund's future performance and future performance of other accounts of Calamos may vary.

Calamos and its principals, officers, employees, and affiliates may buy and sell securities or other investments for their own accounts and may have actual or potential conflicts of interest with respect to investments made on the Fund's behalf. As a result of differing trading and investment strategies or constraints, positions may be taken by principals, officers, employees, and affiliates of Calamos that are the same as, different from, or made at a different time than positions taken for the Fund.

Calamos' investment management fee is a percentage of the Fund's managed assets, and Calamos' investment management fee will be higher if the Fund sells additional common shares or employs leverage. Accordingly, Calamos will benefit from the sale of additional common shares, preferred shares, or debt securities and may have an incentive to be more aggressive with respect to the use of leverage by the Fund.

LEVERAGE

The Fund may issue preferred shares or debt securities or borrow to increase its assets available for investment. As of January 31, 2021, the Fund had $29.9 million in borrowings outstanding under the SSB Agreement, MRP Shares outstanding with an aggregate liquidation preference of $100 million and used approximately $342.5 million of collateral obtained through securities lending arrangements as an offset against borrowings under the SSB Agreement, for a total of $472.4 million of leverage representing 30.6% of managed assets as of that date. The SSB Agreement provides for additional credit availability for the Fund, such that it may borrow up to $430 million. Additional information regarding the Fund's preferred shares is included below under "Mandatory Redeemable Preferred Shares."

As a non-fundamental policy, the Fund may not issue preferred shares, borrow money and/or issue debt securities with an aggregate liquidation preference and aggregate principal amount exceeding 38% of the Fund's managed assets measured at the time of borrowing or issuance of the new securities. However, the Board of Trustees reserves the right to issue preferred shares or debt securities or borrow to the extent permitted by the 1940 Act or under any order issued by the SEC.

The holders of preferred shares will be entitled to receive a preferential liquidating distribution, which is expected to equal the original purchase price per preferred share plus accumulated and unpaid dividends, whether or not declared, before any distribution of assets is made to holders of common shares. The 1940 Act requires that the holders of any preferred shares, voting separately as a single class, have the right to elect at least two Trustees at all times. The remaining Trustees will be elected by holders of common shares and preferred shares, voting together as a single class. The holders of any preferred shares have the right to elect a majority of the Trustees at any time two years' accumulated dividends on any preferred shares are unpaid.

The Fund also may borrow money as a temporary measure for extraordinary or emergency purposes, including the payment of dividends and the settlement of securities transactions, which otherwise might require

untimely dispositions of the Fund's holdings. When the Fund leverages its assets, the fees paid to Calamos for investment management services will be higher than if the Fund did not leverage because Calamos' fees are calculated based on the Fund's managed assets, which include the proceeds of the issuance of preferred shares or debt securities or any outstanding borrowings. Consequently, the Fund and Calamos may have differing interests in determining whether to leverage the Fund's assets. The Fund's Board of Trustees monitors any such potential conflicts of interest on an ongoing basis.

The Fund's use of leverage is premised upon the expectation that the Fund's leverage costs will be lower than the return the Fund achieves on its investments with the leverage proceeds. Such difference in return may result from the Fund's higher credit rating or the short-term nature of its borrowing compared to the lower credit quality, long-term nature of its investments. Because Calamos seeks to invest the Fund's managed assets (including the assets obtained from leverage) in a portfolio of potentially higher yielding investments or portfolio investments with the potential for capital appreciation, the holders of common shares will be the beneficiaries of any incremental return but will bear the risk of loss on investments made with the leverage proceeds. Should the differential between the Fund's return on its investments made with the proceeds of leverage and the cost of the leverage narrow, the incremental return "pick up" will be reduced or the Fund may incur losses. If long-term interest rates rise without a corresponding increase in the yield on the Fund's portfolio investments or the Fund otherwise incurs losses on its investments, the Fund's net asset value attributable to its common shares will reflect the decline in the value of portfolio holdings resulting therefrom.

Leverage creates risks which may adversely affect the return for the holders of common shares, including:

• the likelihood of greater volatility in the net asset value and market price of common shares;

• fluctuations in the dividend rates on any preferred shares borne by the Fund or in interest rates on borrowings and short-term debt;

• increased operating costs, which are effectively borne by common shareholders, may reduce the Fund's total return; and

• the potential for a decline in the value of an investment acquired with borrowed funds, while the Fund's obligations under such borrowing remains fixed.

Calamos may determine to maintain the Fund's leveraged position if it expects that the long-term benefits to the Fund's common shareholders of maintaining the leveraged position will outweigh the current reduced return. Capital raised through the issuance of preferred shares or debt securities or borrowing will be subject to dividend payments or interest costs that may or may not exceed the income and appreciation on the assets purchased. The issuance of preferred shares or debt or borrowing money may involve offering expenses and other costs and may limit the Fund's freedom to pay dividends on common shares or to engage in other activities. See "Dividends and Distributions on Common Shares; Automatic Dividend Reinvestment Plan — Dividends and Distributions on Common Shares." The Fund also may be required to maintain minimum average balances in connection with borrowings or to pay a commitment or other fee to maintain a line of credit; either of these requirements would increase the cost of borrowing over the stated interest rate. The Fund will pay (and common shareholders will bear) any costs and expenses relating to any borrowings by the Fund, including the financial leverage described above, as well as any additional leverage incurred as a result of this offering and to the issuance and ongoing

maintenance of preferred shares or debt securities (for example, the higher management fee resulting from the use of any such leverage, and interest and/or dividend expense and ongoing maintenance). Net asset value will be reduced immediately following any additional offering of preferred shares or debt securities by the costs of that offering paid by the Fund.

The Board reserves the right to change the amount and type of leverage that the Fund uses, and reserves the right to implement changes to the Fund's borrowings that it believes are in the long-term interests of the Fund and its shareholders, even if such changes impose a higher interest rate or other costs or impacts over the intermediate, or short-term time period. There is no guarantee that the Fund will maintain leverage at the current rate, and the Board reserves the right to raise, decrease, or eliminate the Fund's leverage exposure.

Under the 1940 Act, the Fund is not permitted to issue preferred shares unless immediately after such issuance the Fund has an asset coverage of at least 200% of the liquidation value of the aggregate amount of outstanding preferred shares (i.e., such liquidation value may not exceed 50% of the value of the Fund's total assets). Under the 1940 Act, the Fund may only issue one class of senior securities representing equity. So long as preferred shares are outstanding, additional senior equity securities must rank on a parity with the preferred shares. In addition, the Fund is not permitted to declare any cash dividend or other distribution on its common shares unless, at the time of such declaration, the net asset value of the Fund's portfolio (determined after deducting the amount of such dividend or distribution) is at least 200% of such liquidation value. Under the 1940 Act, the Fund is not permitted to incur indebtedness unless immediately after such borrowing the Fund has an asset coverage of at least 300% of the aggregate outstanding principal balance of indebtedness (i.e., such indebtedness may not exceed 33 1/3% of the value of the Fund's total assets). Under the 1940 Act, the Fund may only issue one class of senior securities representing indebtedness other than promissory notes or other evidences of indebtedness not intended to be publicly distributed. Additionally, under the 1940 Act, the Fund generally may not declare any dividend or other distribution upon any class of its shares, or purchase any such shares, unless the aggregate indebtedness of the Fund has, at the time of the declaration of any such dividend or distribution or at the time of any such purchase, an asset coverage of at least 300% after deducting the amount of such dividend, distribution, or purchase price, as the case may be, except that dividends may be declared upon any preferred shares if such indebtedness has an asset coverage of at least 200% at the time of declaration thereof after deducting the amount of the dividend. This limitation does not apply to certain privately placed debt. In general, the Fund may declare dividends on preferred shares as long as there is asset coverage of 200% after deducting the amount of the dividend. The holders of preferred shares or debt, if any, on the one hand, and the holders of the common shares, on the other, may have interests that conflict with each other in certain situations. See "Description of Securities — Preferred Shares" and "Certain Provisions of the Agreement and Declaration of Trust and By-Laws, Including Antitakeover Provisions."

The Fund may be subject to certain restrictions on investments imposed by guidelines of and covenants with one or more rating agencies, which may issue ratings for any debt securities or preferred shares issued by the Fund in the future. These guidelines and covenants may impose asset coverage and portfolio composition requirements that are more stringent than those imposed by the 1940 Act. Certain types of borrowings may result in the Fund being subject to covenants in credit agreements, including those relating to asset coverage, borrowing base and portfolio composition requirements and additional covenants that may affect the Fund's ability to pay dividends and distributions on common shares in certain instances. The Fund also may be required to pledge its assets to the lenders in connection with certain types of borrowings. Certain types of borrowing may involve the rehypothecation of the Fund's securities. Calamos does not anticipate that these covenants or restrictions would adversely affect its ability to manage the Fund's portfolio in accordance with the Fund's investment objective and policies. Due to these covenants or restrictions, the Fund may be forced to liquidate investments at times and at prices that are not favorable to the Fund, or the Fund may be forced to forgo investments that Calamos otherwise views as favorable.

The extent to which the Fund employs leverage will depend on many factors, the most important of which are investment outlook, market conditions and interest rates. Successful use of a leveraging strategy depends on

Calamos' ability to predict correctly interest rates and market movements. There is no assurance that a leveraging strategy will be successful during any period in which it is employed.

Mandatory Redeemable Preferred Shares

On September 6, 2017, the Fund completed a private placement of 1,330,000 Series A MRP Shares, 1,330,000 Series B MRP Shares and 1,340,000 Series C MRP Shares. Each MRP Share has a liquidation preference of $25.00, resulting in an aggregate liquidation preference of $100 million for all MRP Shares.

The holders of MRP Shares for the Fund ("MRP Shareholders") are entitled to receive monthly cash dividends, payable on the first business day (a "Dividend Payment Date") of each month following issuance.

Subject to adjustment as described below under "MRP Shares Dividends," the dividend rate per annum (the "Applicable Rate") for each series of MRP Shares is as follows:

MRP Shares	Applicable Rate
Series A MRP Shares		3.70	%
Series B MRP Shares		4.00	%
Series C MRP Shares		4.24	%

The MRP Shares have a term redemption date of September 6, 2022 for the Series A MRP Shares, September 6, 2024 for the Series B MRP Shares and September 6, 2027 for the Series C MRP Shares.

Previously, the MRP Shares had been assigned a rating of "AA" by Fitch Ratings, Inc. ("Fitch"). As of December 17, 2020, Kroll Bond Rating Agency LLC ("Kroll") replaced Fitch as the rating agency for the MRPS. The MRPS have been assigned a rating of 'AA-' by Kroll. If the ratings of the MRP Shares are downgraded, the Fund's dividend expense may increase, as described below.

Liquidation Preference. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Fund, the MRP Shareholders will be entitled to receive a preferential liquidating distribution equal to $25.00 per MRP Share plus accrued and unpaid dividends, after satisfaction of claims of creditors of the Fund, but before any distribution of assets is made to common shareholders.

MRP Shares Dividends. If, on the first day of the monthly dividend period immediately preceding a Dividend Payment Date (each such period a "Dividend Period"), a series of MRP Shares is rated no less than "A" by Fitch (and no less than the equivalent of such rating by some other NRSRO, if any, other than Fitch, such as Kroll, providing a rating for the MRP Shares pursuant to the request of the Fund), then the dividend rate for such period (the "Dividend Rate") will be equal to the Applicable Rate for such series. If, on the first day of a Dividend Period, the credit rating assigned on any date to a series of MRP Shares by Fitch (or some other NRSRO then rating any series of the outstanding MRP Shares pursuant to the request of the Fund, such as Kroll) is lower than a rating of "A" by Fitch (or lower than the equivalent of such rating by such other rating agency), the Dividend Rate applicable to such series of outstanding MRP Shares for such Dividend Period shall be the Applicable Rate plus the enhanced dividend amount (which shall not be cumulative) set opposite the lowest of such ratings in the table below:

Fitch Rating	Enhanced Dividend Amount
"A-"		0.5	%
"BBB+" to "BBB-"		2.0	%
"BB+" or below		4.0	%

A 4.0% premium in addition to the Applicable Rate may apply when the Fund fails to maintain a current credit rating, and a 5.0% premium may apply when the Fund fails to make timely payments with regard to the MRP Shares (subject to cure periods in each case).

Limitation on Common Share Distributions. So long as any MRP Shares are outstanding, the Fund will not declare, pay or set apart for payment any dividend or other distribution (other than non-cash distributions) with respect to Fund shares ranking junior to or on parity with the MRP Shares, unless (1) the Fund has satisfied the MRP Shares Overcollateralization Test (as defined below) on at least one "valuation date" in the preceding 65 calendar days, (2) immediately after such transaction the Fund would satisfy the MRP Shares Asset Coverage Test (as defined below), (3) full cumulative dividends on the MRP Shares due on or prior to the date of the transaction have been declared and paid to the MRP Shareholders and (4) the Fund has redeemed the full number of MRP Shares required to be redeemed by any provision for mandatory redemption or deposited sufficient monies with the Fund's paying agent for that purpose, subject to certain grace periods and exceptions.

MRP Shares Asset Coverage Test: Asset coverage with respect to all outstanding senior securities and preferred shares, including the MRP Shares, determined in accordance with Section 18(h) of the 1940 Act, on the basis of values calculated as of a time within 48 hours (not including Sundays or holidays) next preceding the time of determination, must be greater than or equal to 225%.

MRP Shares Overcollateralization Test: So long as Fitch or any other NRSRO, such as Kroll, is then rating any class of the outstanding MRP Shares pursuant to the request of the Fund, satisfaction of only those overcollateralization ratios applicable to closed-end fund issuers with the same rating(s) as the Fund's MRP Shares' then-current rating(s) issued by Fitch or such other NRSRO, such as Kroll, by application of the applicable rating agency guidelines.

The terms of the MRP Shares and rights and preferences of the MRP Shareholders are set forth in the Statement of Preferences of Series A Mandatory Redeemable Preferred Shares, Series B Mandatory Redeemable Preferred Shares and Series C Mandatory Redeemable Preferred Shares of the Fund (the "Statement of Preferences").

Redemption. The terms of the MRP Shares provide that: (i) the Fund may redeem the MRP Shares at its option at the liquidation preference plus accrued and unpaid dividends and plus a make-whole premium, subject to notice and other requirements; (ii) the Fund is required to redeem the MRP Shares upon failure to satisfy the MRP Shares Asset Coverage Test (tested monthly) or MRP Shares Overcollateralization Test (tested weekly), subject to cure periods; and (iii) the Fund is required to redeem the MRP Shares on the term redemption date of September 6, 2022 for the Series A MRP Shares, September 6, 2024 for the Series B MRP Shares and September 6, 2027 for the Series C MRP Shares.

Voting Rights. Except as otherwise required in the prospectus, the governing documents of the Fund, or as otherwise required by applicable law, the Fund's preferred shareholders, including the MRP Shareholders, have one vote per share and vote together with the Fund's common shareholders as a single class. The 1940 Act grants the holders of preferred stock the right to elect at least two Trustees at all times (the "Preferred Share Trustees") and the remaining Trustees will be elected by the holders of common stock and preferred stock voting as a single class. Except during any time when the Fund has failed to make a dividend or redemption payment in respect of MRP Shares outstanding, the MRP Shareholders have agreed to vote in accordance with the recommendation of the Board of Trustees on any matter submitted to them for their vote or to the vote of shareholders of the Fund generally.

With respect to the MRP Shares, William R. Rybak and Virginia G. Breen were designated by the Board of Trustees as the Preferred Share Trustees of the Fund. As of January 1, 2021, there were five other Trustees of the Fund, Ms. Stuckey and Messrs. Calamos, Neal, Toub and Wennlund. See "Management of the Fund" in the Fund's statement of additional information. The Fund's preferred shareholders, including the MRP Shareholders,

are entitled to elect a majority of the Trustees of the Fund during any period when (i) at least two years' accumulated dividends on the preferred stock are due and unpaid or (ii) the preferred shares are otherwise entitled under the 1940 Act to elect a majority of the Trustees of the Fund. The MRP Shareholders have certain additional customary voting rights pursuant to the MRP Shares governing documents and the 1940 Act.

The summary information regarding the MRP Shares contained herein is qualified in its entirety by reference to the Statement of Preferences and other documents related to the terms and conditions and the offering of the MRP Shares.

Effects of Leverage

The SSB Agreement provides for credit availability for the Fund, such that it may borrow up to $430 million. As of January 31, 2021, the Fund had utilized $372.4 million of the $430 million available under the SSB Agreement ($29.9 million of borrowings outstanding, and $342.5 million in structural leverage consisting of collateral received from SSB in connection with securities on loan), representing 24.2% of the Fund's managed assets as of that date, and had $100 million of MRP Shares outstanding, representing 6.5% of the Fund's managed assets. Combined, the borrowings under the SSB Agreement and the outstanding MRP Shares represented 30.6% of the Fund's managed assets. Interest on the SSB Agreement is charged on the drawn amount at the rate of Overnight LIBOR plus 0.80%, payable monthly in arrears. Interest on overdue amounts or interest on the drawn amount paid during an event of default will be charged at Overnight LIBOR plus 2.80%. These rates represent floating rates of interest that may change over time. The SSB Agreement has a commitment fee of 0.10% of any undrawn amount. As of January 31, 2021, the interest rate charged under the SSB Agreement was 0.88%. "Net income" payments related to cash collateral in connection with securities lending were 0.44% of the borrowed amount on an annualized basis as of that date, although this amount can vary based on changes in underlying interest rates.

The Fund's MRP Shareholders are entitled to receive monthly cash dividends, at a currently effective dividend rate per annum for each series of MRP Shares as follows (subject to adjustment as described above in "Mandatory Redeemable Preferred Shares"): 3.70% for Series A MRP Shares, 4.00% for Series B MRP Shares and 4.24% for Series C MRP Shares.

To cover the interest expense on the borrowings under the SSB Agreement (including "net income" payments made with respect to borrowings offset by collateral for securities on loan) and the dividend payments associated with the MRP Shares, based on rates in effect on January 31, 2021, the Fund's portfolio would need to experience an annual return of 0.49% (before giving effect to expenses associated with senior securities).

The Fund will pay, and common shareholders will effectively bear, any costs and expenses relating to any borrowings and to the issuance and ongoing maintenance of preferred shares, including the MRP Shares, or debt securities. Such costs and expenses include the higher management fee resulting from the use of any such leverage, offering and/or issuance costs, and interest and/or dividend expense and ongoing maintenance.

covenants that may affect the Fund's ability to pay dividends and distributions on common shares in certain instances. The Fund may also be required to pledge its assets to the lenders in connection with certain types of borrowings. The Fund may be subject to certain restrictions on investments imposed by guidelines of and covenants with rating agencies for the preferred shares or short-term debt instruments issued by the Fund. These guidelines and covenants may impose asset coverage or portfolio composition requirements that are more stringent than those imposed by the 1940 Act.

The following table illustrates the hypothetical effect on the return to a holder of the Fund's common shares of the leverage obtained by us (and utilized on January 31, 2021). The purpose of this table is to assist you in understanding the effects of leverage. As the table shows, leverage generally increases the return to common shareholders when portfolio return is positive and greater than the cost of leverage and decreases the return when the portfolio return is negative or less than the cost of leverage. The figures appearing in the table are hypothetical and actual returns may be greater or less than those appearing in the table.

Assumed Portfolio Return (Net of Expenses)					(10.00	)%			(5.00	)%			0.00	%			5.00	%			10.00	%
Corresponding Common Share Return⁽¹⁾					(15.10	)%			(7.90	)%			(0.70	)%			6.50	%			13.70	%

(1) Includes interest expense on the borrowings under the SSB Agreement, accrued at interest rates in effect on January 31, 2021 of 0.88%, and dividend expense on the MRP Shares.

For further information about leveraging, see "Risk Factors — Fund Risks — Leverage Risk."

INTEREST RATE TRANSACTIONS

In order to reduce the interest rate risk inherent in the Fund's underlying investments and capital structure, the Fund, if Calamos deems market conditions favorable, may enter into over-the-counter interest rate swap, cap or floor transactions to attempt to protect itself from increasing dividend or interest expenses on its leverage and to hedge portfolio securities from interest rate changes. Fixed-for-floating interest rate swaps involve the Fund's agreement with the swap counterparty to pay a fixed rate payment in exchange for the counterparty agreeing to pay the Fund a payment at a variable rate that is expected to approximate the rate of any variable rate payment obligation on the Fund's leverage. The payment obligations would be based on the notional amount of the swap.

The Fund may use an interest rate cap, which would require it to pay a premium to the counterparty and would entitle it, to the extent that a specified variable rate index exceeds a predetermined fixed rate, to receive from the counterparty payment of the excess amount based on a stated notional amount. There can be no assurance that the Fund will use interest rate transactions or that, if used, their use will be beneficial to the Fund.

The Fund will usually enter into swaps or caps on a net basis; that is, the two payment streams will be netted out in a cash settlement on the payment date or dates specified in the instrument, with the Fund receiving or paying, as the case may be, only the net amount of the two payments. The Fund intends to segregate with its custodian cash or liquid securities having a value at least equal to the Fund's net payment obligations under any swap transaction, marked-to-market daily.

The use of interest rate swaps and caps is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary portfolio security transactions. Depending on the state of

interest rates in general, the Fund's use of interest rate swaps or caps could enhance or harm the overall performance of the Fund's common shares. To the extent that there is a decline in interest rates for maturities equal to the remaining maturity on the Fund's fixed rate payment obligation under the interest rate swap or equal to the remaining term of the interest rate cap, the value of the swap or cap (which initially has a value of zero) could decline, and could result in a decline in the net asset value of the common shares. If, on the other hand, such rates were to increase, the value of the swap or cap could increase, and thereby increase the net asset value of the common shares. As interest rate swaps or caps approach their maturity, their positive or negative value due to interest rate changes will approach zero.

In addition, if the short-term interest rates effectively received by the Fund during the term of an interest rate swap are lower than the Fund's fixed rate of payment on the swap, the swap will increase the Fund's operating expenses and reduce common share net earnings. For example, if the Fund were to enter into one or more interest rate swaps in a notional amount equal to 75% of its outstanding margin loan under which the Fund would receive a short-term swap rate of 0.08% and pay a fixed swap rate of 0.17% over the term of the swap, the swap would effectively increase Fund expenses and reduce Fund common share net earnings by approximately 0.02% as a percentage of net assets attributable to common shareholders and less than 0.02% as a percentage of managed assets.

If, on the other hand, the short-term interest rates effectively received by the Fund are higher than the Fund's fixed rate of payment on the interest rate swap, the swap would enhance common share net earnings. The example above is purely for illustrative purposes and is not predictive of the actual percentage of the Fund's leverage that will be hedged by a swap, the actual fixed rates that the Fund will pay under the swap (which will depend on market interest rates for the applicable maturities at the time the Fund enters into swaps) or the actual short-term rates that the Fund will receive on any swaps (which fluctuate frequently during the term of the swap, and may change significantly from initial levels), or the actual impact such swaps will have on the Fund's expenses and common share net earnings. In either case, the swap would have the effect of reducing fluctuations in the Fund's cost of leverage due to changes in short term interest rates during the term of the swap.

Buying interest rate caps could enhance the performance of the Fund's common shares by limiting certain leverage expenses. Buying interest rate caps could also increase the operating expenses of the Fund and decrease the net earnings of the common shares in the event that interest rates decline or stay the same or the premium paid by the Fund to the counterparty exceeds the additional amount the Fund would have been required to pay on its preferred shares due to increases in short-term interest rates during the term of the cap had it not entered into the cap agreement. The Fund has no current intention of selling an interest rate swap or cap. The Fund will monitor any interest rate swaps or caps with a view to ensuring that it remains in compliance with the federal income tax requirements for qualification as a regulated investment company.

Interest rate swaps and caps do not involve the delivery of securities or other underlying assets or principal. Accordingly, the risk of loss with respect to interest rate swaps and caps is limited to the net amount of interest payments that the Fund is contractually obligated to make or, if applicable, any premium paid by the Fund. If the counterparty defaults, the Fund would not be able to use the anticipated net receipts under the swap or cap to offset the dividend or interest payments on the Fund's leverage or offset certain losses in its portfolio. Depending on whether the Fund would be entitled to receive net payments from the counterparty on the swap or cap, which in turn would depend on the general state of short-term interest rates at that point in time, such a default could negatively impact the performance of the common shares.

The Fund will not enter into an interest rate swap or cap transaction with any counterparty that Calamos believes does not have the financial resources to honor its obligation under the interest rate swap or cap transaction. Further, Calamos will continually monitor the financial stability of a counterparty to an interest rate swap or cap transaction in an effort to proactively protect the Fund's investments.

In addition, at the time the interest rate swap or cap transaction reaches its scheduled termination date, there is a risk that the Fund will not be able to obtain a replacement transaction or that the terms of the replacement will not be as favorable as on the expiring transaction. If this occurs, it could have a negative impact on the performance of the Fund's common shares.

When preferred shares are outstanding, the Fund may choose or be required to redeem some or all preferred shares or prepay any borrowings. This redemption or prepayment would likely result in the Fund seeking to terminate early all or a portion of any swap or cap transaction. Such early termination of a swap could result in a termination payment by or to the Fund. An early termination of a cap could result in a termination payment to the Fund.

RISK FACTORS

Investing in any of our securities involves risk, including the risk that you may receive little or no return on your investment or even that you may lose part or all of your investment. Therefore, before investing in any of our securities you should consider carefully the following risks, as well as any risk factors included in the applicable prospectus supplement.

Fund Risks

General. The Fund is a diversified, closed-end management investment company designed primarily as a long-term investment and not as a trading tool. The Fund invests primarily in a diversified portfolio of convertible securities and non-convertible income securities. An investment in the Fund's common shares may be speculative and it involves a high degree of risk. The Fund is not a complete investment program. Due to the uncertainty in all investments, there can be no assurance that the Fund will achieve its investment objective.

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.

Convertible Securities Risk. The value of a convertible security is influenced by both the yield of non-convertible securities of comparable issuers and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value tends to increase as prevailing interest rate levels decline.

In the past, broker-dealers and other financial institutions have experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. Although Calamos monitors the creditworthiness of the Fund's counterparties, there can be no assurance that the Fund's counterparties will not experience similar difficulties, possibly resulting in losses to the Fund. If a counterparty becomes bankrupt, or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances. Material exposure to a single or small group of counterparties increases the Fund's counterparty risk.

Correlation Risk. Imperfect correlation between the value of derivative instruments and the underlying assets of the Fund creates the possibility that the loss on such instruments may be greater than the gain in the value of the underlying assets in the Fund's portfolio.

Duration Mismatch Risk. The duration of a derivative instrument may be significantly different than the duration of the related liability or asset.

Volatility Risk. Risk may arise in connection with the use of derivative instruments from volatility of interest rates and the prices of reference instruments.

Leverage Risk. The derivative investments in which the Fund may invest will give rise to forms of financial leverage, which may magnify the risk of owning such instruments. Derivatives generally involve leverage in the sense that the investment exposure created by the derivatives may be significantly greater than the Fund's initial investment in the derivative. Accordingly, if the Fund enters into a derivative transaction, it could lose substantially more than the principal amount invested.

Additionally, as a closed-end investment company registered with the SEC, the Fund is subject to the federal securities laws, including the 1940 Act, the rules thereunder, and various SEC and SEC staff interpretive positions. In accordance with these laws, rules and positions, the Fund may "set aside" liquid assets (often referred to as "asset segregation"), or engage in other SEC or staff-approved measures, to "cover" open positions with respect to certain portfolio management techniques, such as engaging in reverse repurchase agreements, dollar rolls, entering into credit default swaps or futures contracts, or purchasing securities on a when-issued or delayed delivery basis, that may be considered senior securities under the 1940 Act. The Fund intends to cover its derivative positions by maintaining an amount of cash or liquid securities in a segregated account equal to the face value of those positions and by offsetting derivative positions against one another or against other assets to manage the effective market exposure resulting from derivatives in its portfolio. To the extent that the Fund does not segregate liquid assets or otherwise cover its obligations under such transactions, such transactions will be treated as senior securities representing indebtedness for purposes of the requirement under the 1940 Act that the Fund may not enter into any such transactions if the Fund's borrowings would thereby exceed 33 1/3% of its managed assets, less all liabilities and indebtedness of the Fund not represented by senior securities. However, these transactions, even if covered, may represent a form of economic leverage and will create risks. In addition, these segregation and coverage requirements could result in the Fund maintaining securities positions that it would otherwise liquidate, segregating assets at a time when it might be disadvantageous to do so or otherwise restricting portfolio management. Such segregation and cover requirements will not limit or offset losses on related positions.

Regulatory Risk. The enforceability of agreements underlying hedging transactions may depend on compliance with applicable statutory and other regulatory requirements and, depending on the identity of the counterparty, applicable international requirements. New or amended regulations may be imposed by the CFTC, the SEC, the Federal Reserve or other financial regulators, other governmental regulatory authorities or self-regulatory organizations that supervise the financial markets that could adversely affect the Fund. In particular, these agencies are empowered to promulgate a variety of new rules pursuant to recently enacted financial reform legislation in the United States. The Fund also may be adversely affected by changes in the enforcement or interpretation of existing statues and rules by these governmental regulatory authorities or self-regulatory organizations.

In addition, the securities and futures markets are subject to comprehensive statutes, regulations and margin requirements. For instance, the Dodd — Frank Wall Street Reform and Consumer Protection Act ("Dodd-Frank Act") could have an adverse effect on the Fund's ability to use derivative instruments. The Dodd-Frank Act is designed to impose stringent regulation on the over-the-counter derivatives market in an attempt to increase transparency and accountability and provides for, among other things, new clearing, execution, margin, reporting, recordkeeping, business conduct, disclosure, position limit, minimum net capital and registration requirements. Although the CFTC has released final rules relating to clearing, execution, reporting, risk management, compliance, position limit, anti-fraud, consumer protection, portfolio reconciliation, documentation, recordkeeping, business conduct, margin requirements and registration requirements under the Dodd-Frank Act, many of the provisions are subject to further final rulemaking, and thus the Dodd-Frank Act's ultimate impact

remains unclear. New regulations could, among other things, restrict the Fund's ability to engage in derivatives transactions (for example, by making certain types of derivatives transactions no longer available to our funds), increase the costs of using these instruments (for example, by increasing margin, capital or reporting requirements) and/or make them less effective and, as a result, the Fund may be unable to execute its investment strategy. Limits or restrictions applicable to the counterparties with which the Fund engages in derivative transactions could also prevent the Fund from using these instruments, affect the pricing or other factors relating to these instruments or may change availability of certain investments. It is unclear how the regulatory changes will affect counterparty risk.

The Commission recently finalized new Rule 18f-4 under the 1940 Act providing for the regulation of registered investment companies' use of derivatives and certain related instruments. Compliance with Rule 18f-4 will not be required until approximately the middle of 2022. The new rule, among other things, limits derivatives exposure through one of two value-at-risk tests, requires funds to adopt and implement a derivatives risk management program (including the appointment of a derivatives risk manager and the implementation of certain testing requirements), and subjects funds to certain reporting requirements in respect of derivatives. Limited derivatives users (as determined by Rule 18f-4) are not, however, subject to the full requirements under the rule. In connection with the adoption of Rule 18f-4, the Commission also eliminated the asset segregation framework for covering derivatives and certain financial instruments arising from the Commission's Release 10666 and ensuing staff guidance. As the Fund comes into compliance, the Fund's approach to asset segregation and coverage requirements described in this prospectus may be impacted. Rule 18f-4 could restrict the Fund's ability to engage in certain derivatives transactions and/or increase the costs of such derivatives transactions, which could adversely affect the value or performance of the Fund.

General Derivative Risks. Derivatives also involve the risk of mispricing or improper valuation and the risk that changes in the value of a derivative may not correlate perfectly with an underlying asset, interest rate or index. Suitable derivative transactions may not be available in all circumstances and there can be no assurance that the Fund will engage in these transactions to reduce exposure to other risks when that would be beneficial. Furthermore, the skills needed to employ derivatives strategies are different from those needed to select portfolio securities and, in connection with such strategies, the Fund makes predictions with respect to market conditions, liquidity, currency movements, market values, interest rates and other applicable factors, which may be inaccurate. Thus, the use of derivative investments may require the Fund to sell or purchase portfolio securities at inopportune times or for prices below or above the current market values, may limit the amount of appreciation the Fund can realize on an investment or may cause the Fund to hold a security that it might otherwise want to sell. Tax rules governing the Fund's transactions in derivative instruments may also 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, among other things, 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. In addition, there may be situations in which the Fund elects not to use derivative instruments that result in losses greater than if they had been used. Amounts paid by the Fund as premiums and cash or other assets held in margin accounts with respect to the Fund's derivative instruments would not be available to the Fund for other investment purposes, which may result in lost opportunities for gain. Derivative instruments can be illiquid, and may disproportionately increase losses and may have a potentially large impact on Fund performance.

Emerging Markets Risk. Investments in foreign securities may include investments 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. These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could adversely affect the value of the Fund's investments and hurt those countries' economies and securities markets. Securities issued in these countries may be more volatile and less liquid than securities issued in foreign countries with more developed economies or markets. Loss may also result from the imposition of exchange controls, confiscations and other government restrictions, or from problems in share registration, settlement, custody, or other operational risks.

• increased price sensitivity to changing interest rates and to a deteriorating economic environment;

• greater risk of loss due to default or declining credit quality;

• adverse company specific events are more likely to render the issuer unable to make interest and/or principal payments; and

Foreign Securities Risk. Investments in non-U.S. issuers may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced to the extent that the Fund invests a significant portion of its non-U.S. investments in one region or in the securities of emerging market issuers. See also " — Emerging Markets Risk" below. These risks may include: