485APOS

Approximate Date of Proposed Public Offering: As soon as practicable following the effectiveness of the Registration Statement.

Class A, Class C, Class I and Class R shares of Calamos Dividend Growth Fund and Calamos Mid Cap Growth Fund.

This registration statement does not affect the registration of any series or any class of a series of the Registrant not included herein.

Calamos Dividend Growth Fund’s investment objective is seeking income and capital appreciation primarily through investments in dividend paying equities.

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calamos Funds. More information about these and other discounts is available from your financial professional and under “Fund Facts — What classes of shares do the Funds offer?” on page [xx] of the Fund’s prospectus and “Share Classes and Pricing of Shares” on page [xx] of the Fund’s statement of additional information.

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

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then either redeem or do not redeem your shares at the end of the reflected time periods. The example also assumes that your investment has a 5% return each year, that all dividends and capital gain distributions are reinvested, that you pay a maximum initial or contingent deferred sales charge and that the Fund’s operating expenses remain the same. Although your actual performance and costs may be higher or lower, based on these assumptions, your costs would be:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund’s performance.

Under normal market conditions, the Fund invests at least 80% of its net assets (plus borrowing for investment purposes, if any) in dividend-paying equities (including common and preferred stocks and interests or units in Master Limited Partnerships (“MLPs”)). Companies in certain economic sectors of the market have historically provided higher dividend yields than companies in other sectors and industries. Given the Fund’s focus on dividend-paying securities, the Fund may, from time to time, have a greater exposure to these higher dividend-yield sectors and industries than the broad equity market. The Fund may invest up to 25% of its net assets in foreign equity securities. The Fund may invest in options and American Depositary Receipts (ADRs) in furtherance of its investment strategy.

The Fund may invest up to 25% of its net assets in MLPs. MLPs are publically traded partnerships engaged in the transportation, storage, processing, refining, marketing, exploration, production and mining of minerals and natural resources. By confining their operations to these specific activities, their interest or units, are able to trade on public securities exchanges similar to the shares of a corporation, without entity level taxation.

An investment in the Fund is subject to risks, and you could lose money on your investment in the Fund. There can be no assurance that the Fund will achieve its investment objective. The risks associated with an investment in the Fund can increase during times of significant market volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund include:

The Fund has not yet commenced operations, therefore performance information is not yet available. In the future, performance information will be available at no cost by visiting www.calamos.com or by calling 800-582-6969.

For important information about purchase and sale of Fund shares, tax information, and financial intermediary compensation, please turn to “Other Important Information Regarding Fund Shares” on page [xx] of the prospectus.

Calamos Mid Cap Growth Fund’s investment objective is long-term capital appreciation.

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

The Fund seeks to generate excess returns relative to the benchmark over full market cycles. The portfolio will, under normal market conditions, invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in the common stock of medium-sized companies. Medium-sized companies are defined as those companies whose market capitalization falls within the range of the companies included in the Russell Mid Cap Growth Index at the time of purchase. As of April 30, 2013, the market capitalization of the Russell Mid Cap Growth Index ranged from $442 million to $28.3 billion. The Fund may continue to hold a security whose market capitalization changes over time, and as a result a potion of the Fund’s holdings may have market capitalization out of this range at any given time. The Fund will seek to invest in companies with high or accelerating growth rates. The Fund may invest in options and American Depositary Receipts (ADRs) in furtherance of its investment strategy.

The Funds’ shares are redeemable. In general, investors may purchase, redeem, or exchange Fund shares on any day the New York Stock Exchange is open by written request (to the address noted above), by wire transfer, by telephone (at the number noted above), or through a financial intermediary. Orders to buy and redeem shares are processed at the next net asset value (share price or “NAV”) to be calculated only on days when the New York Stock Exchange is open for regular trading.

The Funds’ distributions may be taxable as ordinary income or capital gains, except when your investment is in an IRA, 401(k) or other tax-advantaged investment plan.

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

What are the investment objectives and principal strategies common to the Funds?

As described above, each Fund has different investment objectives and strategies, and may invest in different securities. The Funds differ principally in (i) how important growth potential and/or current income is considered when selecting investments, (ii) the types of securities selected as investments, such as equity or foreign securities, and (iii) the risks involved with an investment in a Fund.

When buying and selling growth-oriented securities, the investment adviser focuses on the company’s earnings growth potential coupled with financial strength and stability. When buying and selling value-oriented securities, the investment adviser focuses on how a company’s stock is valued relative to what the Fund’s investment adviser considers to be the company’s worth, the financial strength of the issuer and whether there is a near-term catalyst that could trigger an increase in the stock’s price. Whether examining growth-oriented or value-oriented securities for selection, the Fund focuses on individual stock selection (referred to as a “bottom-up approach”) and quantitative research.

In seeking to meet the Funds’ respective investment objectives, the Funds’ investment adviser utilizes highly disciplined institutional management strategies designed to help enhance investment returns while managing risk. As part of these strategies, an in-depth proprietary analysis is employed on an issuing company and its securities. At the portfolio level, risk management tools are also used, such as diversification across companies, sectors and industries to achieve a risk-reward profile suitable for each Fund’s objectives.

A Fund’s investment objectives may not be changed without the approval of a “majority of the outstanding” shares of that Fund, as defined in the Investment Company Act of 1940. There can be no assurance that a Fund will achieve its investment objectives.

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

As with any security, there are market and investment risks associated with your investment in the Funds. The value of your investment will fluctuate over time, and it is possible to lose money.

In response to market, economic, political, or other conditions, a Fund may temporarily use a different investment strategy for defensive purposes. If a Fund does so, different factors could affect the Fund’s performance, and the Fund may not achieve its investment objective.

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

Market Disruption Risk. Certain events have a disruptive effect on securities markets, including but not limited to, terrorist attacks, war and other geopolitical events or catastrophes. The Funds’ investment adviser, CALAMOS ADVISORS, cannot predict the effect of similar events in the future on the U.S. or foreign economies. Certain securities such as high yield and equity securities tend to be impacted more by these events than other types of securities in terms of price and volatility.

Recent Market Events. Over the last several years, domestic and international markets have experienced acute 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. In addition, many governments and quasi-governmental entities throughout the world 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. An unexpected or quick reversal of these policies could increase volatility in the equity and debt markets. These market conditions and continuing economic risks add significantly to the risk of short-term volatility in the Funds.

Investment Management Risk. Whether a Fund achieves its investment objective(s) is significantly impacted by whether CALAMOS ADVISORS is able to choose suitable investments for each Fund.

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

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

Growth Stock Risk. Growth securities experience relatively rapid earnings growth and typically trade at higher multiples of current earnings than other securities. Therefore, growth securities may be more sensitive to changes in current or expected earnings than other securities. Growth securities also may be more volatile because growth companies usually invest a high portion of earnings in their business, and they may lack the dividends of value stocks that can lessen the decreases in stock prices in a falling market. A company may never achieve the earnings expansion the Fund anticipates.

Value Stock Risk. Value stocks involve the risk that they may never reach what CALAMOS ADVISORS believes is their full market value, either because the market failed to recognize the stocks’ intrinsic worth or CALAMOS ADVISORS misgauged that worth. Because different types of stocks tend to shift in and out of favor depending on market conditions, a value fund’s performance may sometimes be higher or lower than that of other types of funds (such as those emphasizing growth stocks).

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

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

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

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. A 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 a Fund’s holdings. A Fund’s ability to use forward foreign currency transactions successfully depends on a number of factors, including the forward foreign currency transactions being available at attractive prices, the availability of liquid markets and the ability of the portfolio managers to accurately predict the direction of changes in currency exchange rates. Currency exchange rates may be volatile and may be affected by, among other factors, the general economics of a country, the actions of U.S. and foreign governments or central banks, the imposition of currency controls and speculation. Currency transactions are also subject to the risk that the other party in the transaction will default its contractual obligation, which would deprive a Fund of unrealized profits or force a Fund to cover its commitments for purchase or sale of a currency, if any, at the current market price. If a Fund enters into a forward foreign currency contract, its custodian will segregate liquid assets of the Fund having a value equal to the Fund’s commitment under such forward contract from day to day, except to the extent that the Fund’s forward contract obligation is covered by liquid portfolio securities denominated in, or whose value is tied to, the currency underlying the forward contract.

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

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

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

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

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

Tax Risk. The federal income tax treatment of convertible securities or other securities in which the Funds may invest may not be clear or may be subject to recharacterization by the Internal Revenue Service. It could be more difficult to comply with the tax requirements applicable to regulated investment companies if the tax characterization of investments or the tax treatment of the income from such investments were successfully challenged by the Internal Revenue Service. Any such failure to comply with the rules applicable to regulated investment companies could make it more difficult for the Fund itself to comply with such rules.

MLP Risk — Investments in securities of MLPs involve risk that differ from investments in common stock, including risks related to limited control and limited rights to vote on matters affecting the MLP, risks related to the potential conflicts of interest between the MLP and the MLPs general partners, cash flow risks, dilution risks and risks related to the general partners right to acquire until holders to sell their common units at an undesirable time or price.

MLP Tax Risk — MLPs do not pay federal income tax at the partnership level. Rather, each parent is allocated a share of the partnerships’ income, gains, losses, deductions and credits. A change in current tax law, or a change in the underlying business of an MLP, could result in an MLP being treated as a corporation, instead of a partnership, for federal income tax purposes, which would result in such MLP being required to pay income tax on its taxable income. This would have the effect of reducing the amount of cash available for distribution by the MLP, potentially reducing the value of the Fund’s investment and consequently your investment in the Fund.

MLP Liquidity Risk — Although common units of MLPs trade on the NYSE, the NASDAQ and Amex, certain MLP securities trade less frequently than those of larger companies due to their smaller capitalization. As a result, the price of such MLPs may display abrupt and erratic movements at times. Additionally it may be more difficult for the Fund to buy and sell significant amounts of such securities without unfavorable impact on prevailing market process. As a result, these securities may be difficult to dispose of at a fair price when the Adviser desires to do so. This may adversely affect the Funds ability to take advantage of other market opportunities or make dividend distributions.

Equity Securities of MLPs Risk — MLP common units, like 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 an issuer or certain market 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, like the prices other equity securities, also can be affected by fundamentals unique to the partnership or company, including earnings power and coverage ratios.

RIC Qualification Risk — To qualify for treatment as a regulated investment company (“RIC”) under the Internal Revenue Code (“Code”), the Fund must meet certain income source, asset diversification and annual distribution requirements. The Fund’s MLP investments may make it more difficult for the Fund to meet these requirements. The asset diversification requirements include a requirement that, at the end of each quarter of each taxable year, not more than 25% of the value of the Fund’s total assets is invested in the securities (including debt securities) of one or more qualified publicly traded partnerships. The Fund anticipates that the MLPs in which it invests will be qualified publicly traded partnerships. If the Fund’s MLP investments exceed this 25% limitation, due to portfolio activity, then the Fund would not satisfy the diversification requirements and could fail to qualify as a RIC. If, in any year, the Fund fails to qualify as a RIC for any reason, the Fund would be taxed as an ordinary corporation and would become (or remain) subject to corporate income tax. The resulting corporate taxes could substantially reduce the Fund’s net assets, the amount of income available for distribution and the amount of our distributions.

A description of the Funds’ policies and procedures in connection with the disclosure of portfolio security holdings of the Funds is available in the statement of additional information and on the Funds’ website, www.calamos.com.

The Funds’ investments are managed by CALAMOS ADVISORS LLC, 2020 Calamos Court, Naperville, IL. CALAMOS ADVISORS is an indirect subsidiary of CALAMOS ASSET MANAGEMENT, INC., whose voting shares are majority-owned by CALAMOS FAMILY PARTNERS, INC., which is controlled by John P. Calamos, Sr. and the Calamos family.

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

A discussion regarding the basis for the approval by the board of trustees of the management agreement for the Funds will be included in the Funds’ annual report to shareholders for the fiscal year ending October 31, 2013.

John P. Calamos, Sr. During the past five years, John P. Calamos, Sr. has been President and Trustee of the Calamos Investment Trust (“Trust”) and Chairman, CEO and Global Co-CIO of CALAMOS ADVISORS as of August 31, 2012, prior thereto he was Chairman, CEO and Co-CIO of CALAMOS ADVISORS and its predecessor company.

Gary D. Black. Gary D. Black became the Executive Vice President, Global Co-CIO and CIO of Alternative Strategies of CALAMOS ADVISORS as of August 31, 2012. Mr. Black served as Chief Executive Officer and Chief Investment Officer, and was a Founding Member of Black Capital LLC from July 2009 until August 2012, prior thereto, Mr. Black served as Chief Executive Officer of Janus Capital Group from January 2006 through July 2009.

Jeff Scudieri. Jeff Scudieri joined CALAMOS ADVISORS in 1997 and has been a Senior Vice President and Co-Head of Research and Investment since July 2010, prior thereto he was a senior strategy analyst between September 2002 and July 2010.

Jon Vacko. Jon Vacko joined CALAMOS ADVISORS in 2000 and has been a Senior Vice President and Co-Head of Research and Investments since July 2010, prior thereto he was a senior strategy analyst between July 2002 and July 2010.

Dennis Cogan. Dennis Cogan joined CALAMOS ADVISORS in March 2005 and since March 2013 is a Co-Portfolio Manager. Between March 2005 and March 2013 he was a senior strategy analyst.

John Hillenbrand. John Hillenbrand joined CALAMOS ADVISORS in 1994 and since March 2013 is a Co-Portfolio Manager. Between July 2001 and March 2013 he was a senior strategy analyst.

Steve Klouda, Steve Klouda joined CALAMOS ADVISORS in 1994 and since March 2013 is a Co-Portfolio Manager. Between July 2002 and March 2013 he was senior strategy analyst.

Nick Niziolek. Nick Niziolek joined CALAMOS ADVISORS in March 2005 and since March 2013 is a Co-Portfolio Manager. Between March 2005 and March 2013 he was a senior strategy analyst.

Joe Wysocki. Joe Wysocki joined CALAMOS ADVISORS in October 2003 and since March 2013 is a Co-Portfolio Manager. Between February 2007 and March 2013 he was a senior strategy analyst.

Jeff Miller. Jeff Miller joined CALAMOS ADVISORS in July 2012 and since March 2013 is a Co-Portfolio Manager. Between July 2012 and March 2013 he was a senior strategy analyst, Value Team. Prior thereto he was Portfolio Manager and President of Value Equities at American Independence Financial Services LLC.

Ariel Fromer. Ariel Fromer joined CALAMOS ADVISORS in July 2012 and since March 2013 is a Co-Portfolio Manager. Between July 2012 and March 2013 she was a senior strategy analyst, Value Team. Prior thereto she was Portfolio Manager and Vice President of Value Equities at American Independence Financial Services LLC.

Tammy Miller. Tammy Miller joined CALAMOS ADVISORS in July 2012 and since March 2013 is a Co-Portfolio Manager. Between July 2012 and March 2013 she was a senior strategy analyst, Value Team. Prior thereto she was Vice President of Research at American Independence Financial Services LLC.

The Funds’ statement of additional information provides additional information about the team leaders, including other accounts they manage, their ownership in the CALAMOS FAMILY OF FUNDS and their compensation.

Team Approach to Management. CALAMOS ADVISORS employs a team approach to portfolio management, led by the Global Co-CIOs and comprised generally of the Global Co-CIOs, Co-Heads of Research and Investments and Co-Portfolio Managers. The

Global Co-CIOs, Co-Heads of Research and Investments and Co-Portfolio Managers are supported by and lead a team of investment professionals whose valuable contributions create a synergy of expertise that can be applied across many different investment strategies.

CALAMOS ADVISORS has an Investment Committee (“Investment Committee”) that performs the following functions:

The Investment Committee operates as a team and consists of our Global Co-CIOs, who will lead the Committee, and a select group of senior investment professionals. Other members of the investment team will also participate in Committee meetings in connection with specific investment related issues or topics as deemed appropriate. Membership of the Investment Committee may be modified to ensure we adapt to dynamic economic, capital market and investment environments as well as incorporate diverse views into our investment process. Portfolio holdings are reviewed and trading activity is discussed on a regular basis by team members. Team members, including the Global Co-CIOs, Co-Heads of Research and Investments and Co-Portfolio Managers, may each make trading decisions guided by each respective Fund’s investment objective and strategy.

While day-to-day management of each portfolio is a team effort, the Global Co-CIOs, along with the Co-Heads of Research and Investments and Co-Portfolio Managers, have joint primary and supervisory responsibility for each of the Funds and work with all team members in developing and executing each respective portfolio’s investment program. Each member of the senior investment team is further identified below.

John P. Calamos, Sr. and Gary D. Black, Global Co-CIOs of CALAMOS ADVISORS, generally focus on firm-wide risk management and the top-down approach of diversification by country and industry sector and macro-level investment themes. As Global Co-CIOs, Messrs. John P. Calamos, Sr. and Gary D. Black direct the team’s focus on the macro themes upon which the portfolio’s strategy is based. For Mid Cap Growth Fund, the team, as a whole, implements the investment strategies, under the general direction and supervision of the Global Co-CIOs, as well as the Co-Heads of Research and Investments, Jeff Scudieri and Jon Vacko, and the Co-Portfolio Managers. John P. Calamos, Sr. and Gary D. Black, along with Jeff Scudieri and Jon Vacko, are responsible for the day-to-day management of the team, bottom-up research efforts and strategy implementation. John Hillenbrand, Steve Klouda, Dennis Cogan, Nick Niziolek, Joe Wysocki, Jeff Miller, Ariel Fromer and Tammy Miller are each Co-Portfolio Managers for the Funds for which they have been so designated. Collectively Mr. Miller, Ms. Fromer and Ms. Miller are referred to as the (“Dividend Growth Team”). With regard to the Dividend Growth Fund, the Investment Committee, headed by Messrs. John Calamos, Sr. and Gary D. Black, will direct the team’s focus on the macro themes upon which the portfolio’s strategy is based. However, the Dividend Growth Team will be responsible for the day-to-day management of the portfolio, including buy and sell decisions of underlying investments, and will implement the investment strategies, under the general direction and supervision of the Global Co-CIOs.

This prospectus offers two classes of shares of each Fund: Class A and Class C shares. Class I shares and Class R shares, which have different expense structures, are offered by a separate prospectus. The different classes of Fund shares are investments in the same portfolio of securities, but each class of shares has different expenses and will likely have different NAVs. The main differences among Class A and Class C shares lie primarily in their initial and contingent deferred sales charge structures and their distribution fees. Class A shares generally bear an initial sales charge at the time of purchase, while Class C shares generally bear a contingent deferred sales charge at the time of redemption. Both share classes bear distribution and/or service fees. Please see “Exchange for Class I Shares” and the “How can I buy shares — By Exchange” sections of this prospectus for a discussion of certain exchange features of the Class A and Class C shares.

For each Fund, the offering price for Class A shares is the NAV per share plus an initial sales charge. For each Fund, the maximum sales charge is 4.75% of the offering price. The sales charge varies depending on the amount of your purchase, as follows:

Class A shares also have a 0.25% distribution (12b-1) fee. See “Distribution and service (Rule 12b-1) plan” for more information about distribution fees.

As the table above shows, the larger your investment, the lower your initial sales charge on Class A shares. Each investment threshold that qualifies for a lower sales charge is known as a “breakpoint.” You may be able to qualify for a breakpoint on the basis of a single purchase or by aggregating the amounts of more than one purchase in the following ways:

You may combine the value at the current public offering price of Class A, B and C shares of any Funds within the CALAMOS FAMILY OF FUNDS already owned and Fidelity Prime Money Market Fund Shares (discussed below) previously purchased by exchanging from Calamos Fund shares with a new purchase of Class A shares of any Fund within the CALAMOS FAMILY OF FUNDS to reduce the sales charge on the new purchase. The sales charge for the new shares will be figured at the rate in the table above that applies to the combined value of your current and new investment.

Under a letter of intent, you may purchase additional Class A shares of any Fund over a 13-month period and receive the same sales charge as if you had purchased all the shares at once. A letter of intent does not obligate you to purchase or sell additional Class A shares. See the statement of additional information for more information about letters of intent.

You may purchase a Fund’s Class A shares at the NAV without a sales charge provided that the total amount invested in Class A shares of all Funds within the CALAMOS FAMILY OF FUNDS totals at least $1,000,000. Shares purchased at NAV in an account with a value of $1,000,000 without a sales charge may incur a contingent deferred sales charge of 1.00% if sold within two years after purchase, excluding shares purchased from the reinvestment of dividends or capital gains distributions. See “Contingent deferred sales charges” for more information about contingent deferred sales charges.

You may aggregate your eligible accounts with the eligible accounts of members of your immediate family to obtain a breakpoint discount. The types of eligible accounts that may be aggregated to obtain the breakpoint discounts described above include:

For the purpose of obtaining a breakpoint discount, members of your “immediate family” include your spouse, child, stepchild, parent, stepparent, sibling, grandchild and grandparent, in each case including in-law and adoptive relationships. In addition, a fiduciary can count all shares purchased for a trust, estate or other fiduciary account (including one or more employee benefit plans of the same employer) that has multiple accounts. Eligible accounts include those registered in the name of your financial intermediary through which you own CALAMOS FAMILY OF FUNDS shares.

Any of the following investors may purchase Class A shares of a Fund at NAV, with no initial sales charge:

Proceeds of Class A shares redeemed from a Fund within the previous 60 days may be reinvested in Class A shares of that Fund at NAV without a sales charge.

How do I obtain a breakpoint discount or purchase Class A shares without a sales charge?

The steps to obtain a breakpoint discount depend on how your account is maintained with the CALAMOS FAMILY OF FUNDS. To obtain any of the breakpoint discounts described above, you must notify us or your financial advisor at the time you purchase shares of each eligible account you or a member of your immediate family maintains. For example, if an initial investment that was less than $1,000,000 grows to over $1,000,000, you must tell us or your financial advisor that you qualify to purchase Class A shares without an initial sales charge when you make a subsequent investment. If you do not let us or your financial advisor know of all of the holdings or planned purchases that make you eligible for a reduction, you may not receive a discount to which you are otherwise entitled. If you make your investment through a financial advisor, it is solely your financial advisor’s responsibility to ensure that you receive discounts for which you are eligible, and the Funds are not responsible for a financial advisor’s failure to apply the eligible discount to your account. You may be asked by us or your financial advisor for account statements or other records to verify your discount eligibility, including, where applicable, records for accounts opened with a different financial advisor and records of accounts established by members of your immediate family. If you own shares exclusively through an account maintained with the Funds’ transfer agent, you will need to provide the foregoing information to us at the time you purchase shares. Additional information regarding sales loads and discounts applicable to us may be found in the Funds’ statement of additional information, which can be obtained on CALAMOS ADVISORS’ website at www.calamos.com.

Holders of Class A shares issued by Funds in the CALAMOS FAMILY OF FUNDS may exchange their Class A shares for Class I shares provided that they: (1) hold their shares through an institution that has a valid Class I sales agreement with CFS authorizing such an exchange; and (2) are eligible to invest in Class I shares in accordance with the criteria set forth in the Class I shares prospectus. Any such exchange is subject to the Funds’ discretion to accept or reject the exchange. No sales charges or other charges will apply to any such exchange, including any contingent deferred sales charge that would otherwise apply to the redemption within two years of purchase of Class A shares originally purchased at net asset value pursuant to the $1,000,000 purchase order privilege. For federal income tax purposes, a same-Fund exchange generally will not result in the recognition by the investor of a capital gain or loss. However, investors should consult their own tax or legal adviser to discuss their particular circumstances. Class A shareholders should contact their financial institution for information on the availability of Class I shares, and should read and consider the Class I shares prospectus before any such exchange.

The offering price for Class C shares is the NAV per share with no initial sales charge. However, each Fund pays an aggregate distribution and service fee at the annual rate of 1.00% of average net assets. As a result, the annual expenses for Class C shares are somewhat higher compared to Class A shares, which pay an aggregate 0.25% distribution fee.

Class C shares have a contingent deferred sales charge of 1.00% for any shares redeemed within one year of purchase, measured from the first day of the month in which the shares were purchased. Class C shares DO NOT convert to Class A shares. No order for Class C shares of any Fund may exceed $1,000,000.

Certain Class C shareholders may be eligible to exchange their shares for Class I shares in the same fund, provided that they: (1) hold their shares through an institution that has a valid Class I sales agreement with CFS authorizing such an exchange; and (2) are otherwise eligible to invest in Class I shares through their financial institution in accordance with the criteria set forth in the Class I shares prospectus. In addition, shareholders must have held the Class C shares being exchanged for a minimum of one year from the date of purchase of those shares. Generally, shareholders will not recognize a gain or loss for federal income tax purposes upon such an exchange. Investors should contact their financial intermediary to learn more about the details of this privilege, and should read and consider the Class I shares prospectus before any such exchange. Each such exchange is subject to the discretion of the Trust to accept or reject the exchange.

If you wish to exchange your Fund shares for shares of a money market fund, you may exchange them for shares of the Fidelity Institutional Money Market-Prime Money Market Portfolio (“Fidelity Prime Money Market Fund Shares”). Class A and Class C shares of the Funds may be exchanged for Class III and Class IV Fidelity Prime Money Market Fund Shares, respectively.

Fidelity Prime Money Market Fund Shares are offered by a separate prospectus and are not offered by the Funds. You may at any time exchange your Fidelity Prime Money Market Fund Shares back into shares of the equivalent class of the CALAMOS FAMILY OF FUNDS. However, should you redeem (and not exchange) your Fidelity Prime Money Market Fund Shares, you would pay any applicable contingent deferred sales charge. For a prospectus and more complete information on Fidelity Prime Money Market Fund Shares, including management fees and expenses, please call 800.582.6959. Please read the prospectus relating to Fidelity Prime Money Market Fund Shares carefully.

Any contingent deferred sales charge on redemptions of Class C shares is based on the lesser of the redemption price or purchase price of the Fund shares. For purposes of determining a contingent deferred sales charge, Fund shares are considered sold on a first-in, first-out basis. The contingent deferred sales charge may be waived under certain circumstances. See the statement of additional information for more information about the contingent deferred sales charge.

Each Fund reserves the right to modify the extent to which sales of shares are limited and may, in its sole discretion, permit purchases of shares where, in the judgment of management, such purchases do not have a detrimental effect on the portfolio management of the Fund or its Shareholders. Notwithstanding the forgoing, each Fund continues to reserve the right to reject any order for the purchase of shares in whole or in part for any reason, and to suspend the sale of shares to the public in response to conditions in the securities markets or otherwise.

The decision as to which class of shares you should purchase depends on a number of factors, including the amount and intended length of your investment. An investor making an investment that qualifies for reduced sales charges might consider Class A shares. An investor who prefers not to pay an initial sales charge, but who plans to redeem the shares within eight years might consider Class C shares. For more information about the two share classes, consult your financial advisor or call us toll free at 800.582.6959. Please note that financial services firms may receive different compensation depending upon which class of shares they sell.

The minimum initial investment for Class A shares and Class C shares of each Fund is $2,500 per Fund account. For certain qualified retirement plans, such as individual retirement accounts, the minimum initial investment is $500 per Fund account. The minimum subsequent investment in any Fund is $50 per Fund account. No Fund may waive or reduce the minimum initial or subsequent investment requirement, except for any omnibus account or fee-based program of any financial intermediary with whom CALAMOS ADVISORS has entered into an agreement, including, without limitation, profit sharing or pension plans, Section 401(k) plans and Section 403(b)(7) plans in the case of employees of public school systems and certain non-profit organizations.

You may buy shares of the Funds by contacting us, your financial advisor or the broker-dealer that gave you this prospectus. Your financial advisor or another intermediary may charge for its services. You may purchase shares from us directly without any additional charges other than those described above. When you buy shares, be sure to specify whether you want Class A or Class C shares.

The offering price for shares will be based on the NAV per share next computed after receipt by the Funds’ transfer agent of your purchase order in good form on any day the New York Stock Exchange (the “NYSE”) is open for trading. Generally, if you place your order by 4:00 p.m. Eastern time, you will receive that day’s offering price. Orders placed after 4:00 p.m. Eastern time will receive the following business day’s offering price.

We generally do not sell Fund shares to investors residing outside the U.S., Puerto Rico, Guam and the U.S. Virgin Islands, even if they are U.S. citizens or lawful permanent residents of the U.S. We will sell shares to investors residing outside the U.S. if they have U.S. military APO or FPO addresses.

Each purchase of shares is confirmed by a written statement mailed to the shareholder, without issuance of share certificates. You may buy shares using the following methods:

A subsequent investment may be made by detaching the stub from your account statement and sending it with your check in the envelope provided with your statement. All checks must be drawn on a U.S. bank in U.S. funds. A Fund will not accept cashier’s checks in amounts less than $10,000. To prevent check fraud, the Funds will not accept Treasury checks, credit card checks, traveler’s checks, starter checks or checks written by third parties for the purchase of shares. A Fund also will not accept money orders, post-dated checks, post-dated online bill pay checks, or conditional orders for the purchase of shares. A $25 charge will be imposed if any payment submitted for investment is returned, and the investor may be responsible for any loss sustained by the Fund. If you purchase shares by check or by electronic funds transfer via the Automatic Clearing House (“ACH”) Network, and redeem them shortly thereafter, payment may be delayed until the transfer agent is reasonably assured that the check or purchase by ACH has been collected, which may take 15 days.

Please do not mail letters by overnight delivery service or registered mail to the Post Office Box address. The Funds do not consider the U.S. Postal Service or other independent delivery services to be their agents. Therefore, deposit in the mail or with such services, or receipt at U.S. Bancorp Fund Services, LLC post office box, of purchase orders does not constitute receipt by the transfer agent of the Fund.

Once you have established an account, you may make subsequent purchases of $50 or more over the telephone by debiting your bank account. To electronically debit your bank account, you must hold your account at a financial institution that is an ACH member. The Funds will initiate most electronic transfers from your bank account to pay for the share purchase within that same business day. If your order is received prior to generally 4 p.m. Eastern time, your shares will be purchased at the next applicable price calculated on the day your order is placed. To permit telephone purchases, you must authorize telephone purchases on your account application. Call us at 800.582.6959 to purchase shares by telephone or to obtain an account application with the telephone purchase option. If you did not authorize telephone purchases on your original account application, you may request telephone purchases by submitting a request to the Funds’ transfer agent, in writing along with a voided check, at U.S. Bancorp Fund Services, LLC, P.O. Box 701, Milwaukee, WI 53201.

The Funds may modify or terminate the ability to purchase shares by telephone at any time, or from time to time, without notice to shareholders. If your order to purchase shares of a Fund is canceled because your electronic transfer does not clear, you will be charged a $25 service fee, and you will be responsible for any resulting loss incurred by the Fund. The Funds and their transfer agent will be liable for losses resulting from unauthorized telephone purchases only if the Funds do not follow reasonable procedures designed to verify the identity of the caller. You should immediately verify your trade confirmations when you receive them. If an account has more than one owner or authorized person, the Fund will accept telephone instructions from any one owner or authorized person.

You may purchase shares by wiring funds from your bank. To open an account by wire, a completed account application is required before your wire can be accepted. You may mail or deliver by overnight mail your account application to the transfer agent. Upon receipt of your completed application, the transfer agent will establish an account for you. Your bank must include the name of the Fund you are purchasing, your account number, and your name so that monies can be correctly applied. Your bank should transmit funds by wire to:

Before sending any wire, please advise the transfer agent of your intent to wire funds. Wired funds must be received prior to 4:00 p.m. Eastern time to be eligible for same day pricing. Federal fund purchases will be accepted only on a day on which the Fund and the custodian are open for business. The Fund and U.S. Bank, N.A. are not responsible for the consequences of delays resulting from the banking or Federal Reserve wire system, or from incomplete wiring instructions.

You may exchange Class A shares of a Fund for Class A shares of another Fund in the CALAMOS FAMILY OF FUNDS with no sales charge, if you have previously paid a sales charge on the shares you are exchanging. You may exchange Class C shares of a Fund for Class C shares of another Fund in the CALAMOS FAMILY OF FUNDS with no sales charge, and the time period for the contingent deferred sales charge will continue to run. You may exchange Class III Fidelity Prime Money Market Fund Shares for Class A shares of a Fund without paying a sales charge, if you have previously paid a sales charge on the shares you are exchanging. In addition, you may exchange Class C shares of a Fund for Class IV Fidelity Prime Money Market Fund Shares with no sales charge, and the time period for the contingent deferred sales charge will continue to run. See “Money market fund” above.

The registration of the account to which you are making an exchange must be exactly the same as that of the account from which the exchange is made, and the amount you exchange must meet any applicable minimum investment of the Fund being purchased. You may exchange your shares by writing to us at the CALAMOS FAMILY OF FUNDS, c/o U.S. Bancorp Fund Services, LLC, P.O. Box 701, Milwaukee, WI 53201. If you have authorized telephone exchange on your account application, you may also exchange your shares by calling us at 800.582.6959. An exchange may also be made by instructing your financial advisor, who will communicate your instruction to us. An exchange transaction generally is considered a sale and purchase of shares for federal income tax purposes and may result in capital gain or loss.

The exchange privilege is not intended as a vehicle for short-term or excessive trading. Excessive or short-term exchange activity may interfere with portfolio management and have an adverse effect on all shareholders. Accordingly, a Fund may suspend or permanently terminate the exchange privileges of any investor who appears to be engaged in short-term or excessive trading. Although an investor may be precluded from utilizing the exchange privilege, an investor’s ability to redeem shares of a Fund for cash will not be affected.

If you own shares of a Fund, you may purchase additional shares of that Fund periodically through the Automatic Investment Plan. Under the Plan, after your initial investment, you may authorize the Fund to withdraw from your bank checking or savings account an amount that you wish to invest, which must be $50 or more. Your financial institution must be a member of the ACH Network to participate. If you wish to enroll in this Plan, complete the appropriate application form. To obtain the form, call 800.582.6959. The Plan is not available to clients of financial advisors that offer similar investment services. The Funds may terminate or modify this privilege at any time. You may change your withdrawal amount or terminate your participation in the Plan at any time by notifying us by telephone or in writing at least five business days prior to the effective date of the next transaction. A request to change bank information for this Plan may require a signature guarantee. A $25 charge will be imposed if your bank rejects your payment.

You may redeem shares of a Fund by contacting us or your intermediary. Your intermediary may charge for its services. For shares held direct only, you may redeem shares from us directly without any additional charges other than those described below.

Once your instruction to sell shares of a Fund has been received, you may not cancel or revoke your request. It is, therefore, very important that you call us if you have any questions about the requirements for selling shares before submitting your request.

Shares held for you in your broker-dealer’s name must be sold through the broker-dealer.

When your shares are held for you by the Funds’ transfer agent, you may sell your shares by sending a written request to:

U.S. Bancorp Fund Services, LLC, P.O. Box 701, Milwaukee, WI 53201. Your redemption request must:

Certain types of accounts, such as a trust, corporate, nonprofit or retirement account, may require additional documentation for their redemption requests to be deemed to be in good order. In the case of shares held by a corporation, the redemption request must be signed in the name of the corporation by an officer whose title must be stated, and a certified bylaw provision or resolution of the board of directors authorizing the officer to so act may be required. In the case of a trust or partnership, the signature must include the name of the registered shareholder and the title of the person(s) signing on its behalf.

Under certain circumstances, before shares can be redeemed, additional documents may be required in order to verify the authority of the person seeking to redeem.

Please do not mail letters by overnight delivery service or registered mail to the Post Office Box address. The Funds do not consider the U.S. Postal Service or other independent delivery services to be their agents. Therefore, deposit in the mail or with such services, or receipt at U.S. Bancorp Fund Services, LLC post office box, of redemption requests does not constitute receipt by the transfer agent of the Fund.

Unless telephone redemption was declined on your account application, you may redeem your shares by telephone and have proceeds sent by check to your address of record. With the telephone redemption option, you may sell up to $50,000 worth of shares on any day. You may not redeem by telephone shares held in an IRA account or in an account for which you have changed the address within the preceding 30 days.

If you want redemption proceeds sent to your bank account by either wire transfer (at a current cost of $15 per transfer), or electronic funds transfer via the ACH Network at no cost, you must have selected these alternate payment types on the application. If you have authorized telephone redemptions on your original account application, but would like to change the predetermined bank to which proceeds are sent, please submit your request in writing with a signature guarantee or other acceptable form of authentication from a financial institution source, along with a voided check for the new bank account. Only member banks may transmit funds via the ACH network.

If you declined telephone redemptions on your original account application, you may request the telephone redemption privilege at a later date by submitting a request in writing, which may require a signature guarantee or other acceptable form of authentication from a financial institution source. Please send your request along with a voided check to have proceeds deposited directly into your bank account to U.S. Bancorp Fund Services, LLC, P. O. Box 701, Milwaukee, WI 53201.

To redeem shares from your account by telephone, call 800.582.6959. To reduce the risk of fraudulent instruction and to ensure that instructions communicated by telephone are genuine, the Funds will send your redemption proceeds only to the address or bank/brokerage account as shown on their records. The Funds also may record a call, request more information and send written confirmation of telephone transactions. The Funds and their transfer agent will be liable for losses from unauthorized telephone instructions only if the Funds do not follow reasonable procedures designed to verify the identity of the caller. Please verify the accuracy of each telephone transaction as soon as you receive your confirmation statement. If an account has more than one owner or authorized person, the Fund will accept telephone instructions from any one owner or authorized person.

During periods of volatile economic and market conditions, you may have difficulty making a redemption request by telephone, in which case you should make your redemption request in writing.

Broker-dealers or other sales agents may communicate redemption orders by wire to the Funds’ transfer agent. There is no limit on redemption proceeds sent by wire.

Under the Funds’ Systematic Withdrawal Plan, you may request that a Fund periodically redeem shares having a specified redemption value and send you a check for the proceeds. In order to initiate the Systematic Withdrawal Plan, call 800.582.6959

and request a systematic withdrawal form. Your account must have a share balance of $25,000 or more. Withdrawal proceeds are likely to exceed dividends and distributions paid on shares in your account and therefore may deplete and eventually exhaust your account. The periodic payments are redemption proceeds and are taxable as such. The maximum annual rate at which Class C shares in their first year following purchase and Class A shares purchased at NAV pursuant to the $1,000,000 purchase order privilege for two years after the time of purchase under the Systematic Withdrawal Plan is 10% of the NAV of the account. Because a sales charge is imposed on purchases of Fund shares, you should not purchase shares while participating in the Systematic Withdrawal Plan. You may modify or terminate your Systematic Withdrawal Plan by written notice to the transfer agent at least seven business days prior to the start of the month in which the change is to be effective. You may have a check sent to your address of record or you may have proceeds sent to your predetermined bank account via electronic funds transfer through the ACH Network (which may require a signature guarantee).

You may redeem all or any portion of your shares of a Fund and use the proceeds to purchase shares of any of the other Funds in the CALAMOS FAMILY OF FUNDS or Fidelity Prime Money Market Fund Shares if your signed, properly completed application is on file. An exchange transaction generally is considered a sale and purchase of shares for federal income tax purposes and may result in capital gain or loss. See “How can I buy shares? — By exchange” for more information about the exchange privilege.

In addition to the situations described above, the Funds and the Funds’ transfer agent reserve the right to require the MSG in other instances based on the circumstances relative to the particular situation. A MSG is designed to protect shareholders and the funds from fraud by verifying signatures.

The MSG must be obtained from a financial institution that is a participant in the MSG program. You can obtain a signature guarantee from most domestic banks, brokers, dealers including CFS, credit unions, national securities exchanges, registered securities associations, clearing agencies and savings associations, as well as from participants in the New York Stock Exchange Medallion Signature Program and the Securities Transfer Agents Medallion Program (“STAMP”). When obtaining a MSG please discuss with the guarantor the dollar amount of your proposed transaction. It is important that the level of coverage provided by the guarantor’s stamp covers the dollar amount of the transaction or it may be rejected. An assertion or attestation by a notary public is not a MSG and will not be accepted in place of a MSG.

Non-financial transactions including establishing or modifying certain services on an account may require a signature guarantee, signature verification from a Signature Validation Program member or other acceptable form of authentication from a financial institution source. The Funds reserve the right to waive any signature requirement at their discretion.

The Funds reserve the right to pay all or part of a redemption request through an in-kind payment (in the form of securities or other assets instead of cash) if the Adviser reasonably believes that a cash redemption would negatively affect a Fund’s operation or performance or that the redeeming shareholder may be engaged in market timing, frequent trading or other activity disruptive to portfolio management. Shares normally will be redeemed for cash, although each Fund retains the right to redeem some or all of its shares in-kind under unusual circumstances, in order to protect the interests of remaining shareholders, or to accommodate a request by a particular shareholder that does not adversely affect the interest of the remaining shareholders, by delivery of securities selected from its net assets of that Fund during any 90-day period for any one shareholder. Should redemptions by any shareholder exceed such limitation, a Fund will have the option of redeeming the excess in cash or in-kind. In-kind payment means payment will be made in liquid portfolio securities rather than cash. If that occurs, the redeeming shareholder might incur brokerage and/or other transaction costs to convert the securities to cash.

The Funds will send your redemption proceeds to you by check to the address of record or by wire to a predetermined bank or brokerage account. Redemption proceeds paid by wire will normally be sent on the next business day after receipt of the redemption request. The cost of the wire (currently $15) will be deducted from the redemption proceeds if you are redeeming all of your shares or only a specific number of shares. If you are redeeming a specific dollar amount, the wire fee will be deducted from the remaining balance in the account. You may also have proceeds sent directly to a predetermined bank or brokerage account via electronic funds transfer through the ACH Network if your bank or brokerage firm is an ACH member. There is no charge for an electronic funds transfer through the ACH Network and your proceeds will be credited to your account within two to three business days.

Proceeds from the sale of Fund shares will not be sent to you until the check or ACH purchase used to purchase the shares has cleared, which can take up to 15 days after purchase. You may avoid this delay by buying shares with a wire transfer. A Fund may suspend the right of redemption under certain extraordinary circumstances in accordance with the rules of the Securities and Exchange Commission.

Calamos may postpone the payment of redemption proceeds for up to seven calendar days from the date of redemption. In addition, the Funds can suspend and/ or postpone payments of redemption proceeds beyond seven calendar days for:

Due to the relatively high cost of handling small accounts, each Fund may give you 30 days written notice that it intends to redeem your shares, at the NAV of those shares, if your account has a value of less than $500. This would not apply if your account value declined to less than $500 as a result of market fluctuations.

Each Fund’s share price, or NAV, is determined as of the close of regular session trading on the NYSE (normally 4:00 p.m. Eastern Time) each day that the NYSE is open, in accordance with Rule 22c-1 of the 1940 Act. The NYSE is regularly closed on New Year’s Day, the third Mondays in January and February, Good Friday, the last Monday in May, Independence Day, Labor Day, Thanksgiving and Christmas.

The NAV per share for each class of Fund shares is calculated by dividing the pro rata share of the value of all of the securities and other assets of the Fund allocable to that class of Fund shares, less the liabilities allocable to that class, by the number of shares of the class outstanding. When shares are purchased or sold, the order is processed at the next NAV (plus any applicable sales charge) that is calculated on a day when the NYSE is open for trading, after receiving a purchase or sale order. Because the Funds may invest in securities that are primarily listed on foreign exchanges and trade on days when the Funds do not price their shares, a Fund’s NAV may change on days when shareholders will not be able to purchase or redeem the Fund’s shares. If shares are purchased or sold through an intermediary, it is the responsibility of that intermediary to transmit those orders to the Funds’ transfer agent so such orders will be received in a timely manner.

A purchase or sale order typically is accepted when the Funds’ transfer agent or an intermediary has received a completed application or appropriate instruction along with the intended investment, if applicable, and any other required documentation.

The valuation of the Funds’ portfolio securities is in accordance with policies and procedures adopted by and under the ultimate supervision of the board of trustees.

Portfolio securities that are traded on U.S. securities exchanges, except option securities, are valued at the last current reported sales price at the time the Fund determines its NAV. Securities traded in the over-the-counter market and quoted on The NASDAQ Stock Market are valued at the NASDAQ Official Closing Price, as determined by NASDAQ, or lacking a NASDAQ Official Closing Price, the last current reported sale price on NASDAQ at the time a Fund determines its NAV.

When a last sale or closing price is not available, equity securities, other than option securities, that are traded on a U.S. securities exchange and other equity securities traded in the over-the-counter market are valued at the mean between the most recent bid and asked quotations in accordance with guidelines adopted by the board of trustees. Each option security traded on a U.S. securities exchange is valued at the mid-point of the consolidated bid/ask quote for the option security, also in accordance with guidelines adopted by the board of trustees. Each over-the-counter option that is not traded through the Options Clearing Corporation is valued based on a quotation provided by the counterparty to such option under the ultimate supervision of the board of trustees. Fixed-income securities are generally traded in the over-the-counter market and are valued by independent pricing services or by dealers who make markets in such securities. Valuations of fixed income securities consider yield or price of bonds of comparable quality, coupon rate, maturity, type of issue, trading characteristics and other market data and do not rely exclusively upon exchange or over-the-counter prices.

Trading on European and Far Eastern exchanges and over-the-counter markets is typically completed at various times before the close of business on each day on which the NYSE is open. Each security trading on these exchanges or over-the-counter markets may be valued utilizing a systematic fair valuation model provided by an independent pricing service approved by the board of trustees. The valuation of each security that meets certain criteria in relation to the valuation model is systematically adjusted to reflect the impact of movement in the U.S. market after the foreign markets close. Securities that do not meet the criteria, or that are principally traded in other foreign markets, are valued as of the last reported sale price at the time the respective Fund determines its NAV, or when reliable market prices or quotations are not readily available, at the mean between the most recent bid and asked quotations as of the close of the appropriate exchange or other designated time. Trading of foreign securities may not take place on every NYSE business day. In addition, trading may take place in various foreign markets on Saturdays or on other days when the NYSE is not open and on which the respective Fund’s NAV is not calculated.

Each Fund also may use fair value pricing, pursuant to guidelines adopted by the board of trustees and under the ultimate supervision of the board of trustees, if trading in the security is halted or if the value of a security it holds is materially affected by events occurring before the Fund’s pricing time but after the close of the primary market or exchange on which the security is listed. Those procedures may utilize valuations furnished by pricing services approved by the board of trustees, which may be based on market transactions for comparable securities and various relationships between securities that are generally recognized by institutional traders, a computerized matrix system, or appraisals derived from information concerning the securities or similar securities received from recognized dealers in those securities.

When fair value pricing of securities is employed, the prices of securities used by the Fund to calculate its NAV may differ from market quotations or official closing prices. In light of the judgment involved in fair valuations, there can be no assurance that a fair value assigned to a particular security is accurate.

The Funds have a Distribution and Service Plan or “12b-1 Plan.” Under the plan, Class A shares pay a distribution and/or service fee at the annual rate of 0.25% of the average daily net assets of the class. Class C shares pay a service fee at the

annual rate of 0.25% and a distribution fee at the rate of 0.75%. The distribution fees are for the sale of Fund shares, and the service fees are for services provided to shareholders. Since a Fund’s assets are used to pay 12b-1 fees on an ongoing basis, over time those fees will increase the cost of your investment and may cost you more than other types of sales charges. Consequently, long-term shareholders of Class C shares eventually may pay more than the economic equivalent of the maximum initial charges permitted by the Financial Industry Regulatory Authority (“FINRA”). For more information about the 12b-1 Plan, please see the Funds’ statement of additional information.

The Funds may authorize intermediaries to accept purchase, exchange and redemption orders on the Funds’ behalf. An order properly received by an intermediary will be deemed to have been received by the Funds as of the time of receipt by the intermediary. If you buy, exchange or redeem shares through an intermediary, you will pay or receive the Fund’s NAV per share (plus any applicable sales charge) next calculated after receipt and acceptance of the order by the intermediary, after giving effect to any transaction charge imposed by the intermediary. Each Fund’s NAV is determined as of the close of regular session trading on the NYSE (normally 4:00 p.m., Eastern time) each day that the NYSE is open for trading. If you buy and sell Fund shares through an intermediary, that intermediary may charge a fee for that service. Any such charges could constitute a substantial portion of a smaller account and may not be in your best interest. The Funds cannot always identify individual accounts or transactions for an account that is facilitated by an intermediary. Due to differing operational and systems capabilities, an intermediary may calculate sales charges and fees and track transaction activity differently than the Funds. When transacting in Fund shares, be sure you understand how your intermediary calculates sales charges and fees and tracks transaction activity.

Shares of any Fund may be purchased through certain intermediaries that are agents of the Funds for the limited purpose of completing purchases and sales. For services provided by such a company with respect to Fund shares held by that company for its customers, and for shares held in Network Level III accounts, the Fund may pay additional fees for services being provided by the intermediary to the Fund’s shareholders. For shares held in sub-accounts, such as those in qualified retirement plans and often referred to as “sub-transfer agent” or “recordkeeping fees,” The annual fee may either be a percentage of the account’s average annual net assets or a specific dollar amount per account, determined on the basis of how the intermediary charges. The Board of Trustees of the Funds have set maximum limits to these payments.

The Funds’ Adviser or Distributor, out of their own resources and without additional cost to a Fund or its shareholders, may provide additional cash compensation to intermediaries selling shares of a Fund, including third-party administrators of qualified plans whose customers have purchased Fund shares. These amounts would be in addition to the distribution payments made by a Fund under the distribution and service (Rule 12b-1) agreements described above and are commonly referred to as “revenue sharing” payments. These payments are generally a percentage of the account’s average annual net assets.

The Funds’ Adviser or the Distributor may provide additional non-cash compensation to third parties selling the Funds, including affiliated companies, in accordance with relevant FINRA guidelines governing non-cash compensation. The Distributor may also pay concessions in addition to those described above to broker-dealers so that the Funds are made available by those broker-dealers for their customers.

Payments to Intermediaries may create a conflict of interest by influencing the broker-dealer or other Intermediary and your salesperson to recommend a Fund over another investment. Ask your salesperson or visit your Intermediary’s website for more information.

The Funds are required to comply with various federal anti-money laundering laws and regulations. Consequently, the Funds will request the following information from all investors: full name, date of birth, Social Security number and permanent street address. Corporate, trust, and other entity accounts must provide additional documentation. The Funds will use this information to verify your identity. The Funds will return your application and the monies received to establish your account if any of this information is missing. After your account is established, the Funds may request additional information from you to assist in verifying your identity. If the Funds are unable to verify your identity, they reserve the right to redeem your account at the current day’s NAV. If at any time the Funds believe you may be involved in suspicious activity or if your identifying information matches

information on government lists of suspicious persons, the Funds may choose not to establish a new account or may be required to “freeze” your account. The Funds also may be required to provide a governmental agency with information about your attempt to establish a new account or about transactions that have occurred in your account. The Funds also may be required to transfer monies received to establish a new account, transfer an existing account or transfer the proceeds of an existing account to a governmental agency. In some circumstances, the law may not permit a Fund to inform you that it has taken the actions described above.

The Funds reserve the right to reject any order for the purchase of shares in whole or in part for any reason, and to suspend the sale of shares to the public in response to conditions in the securities markets or otherwise. The Fund generally expects to inform any investor within 24 hours if a purchase order has been rejected. The Funds are intended for long-term investment purposes only, and are not intended for short-term or excessive trading. Those practices may disrupt portfolio management strategies and/or increase expenses, thus harming Fund performance.

Each Fund may, in its discretion, suspend, and may permanently terminate, the purchase privileges or the purchase portion of exchange privileges of any investor who engages in trading activity that the Fund believes would be disruptive to the Fund. Although each Fund will attempt to give prior notice of a suspension or termination of such privileges when it is reasonably able to do so, the suspension or termination may be effective immediately, thereby preventing any uncompleted exchange.

In addition, the Funds receive purchase and sale orders through intermediaries and cannot always identify or reasonably detect short-term or excessive trading that may be facilitated by those intermediaries or by the use of omnibus accounts by those intermediaries. Omnibus accounts are comprised of multiple investors whose purchases and redemptions are aggregated and netted before being submitted to the Funds, making it more difficult to locate and eliminate short-term or excessive trading. To the degree a Fund is able to identify excessive or short-term trading in accounts maintained by intermediaries, the Fund will seek the cooperation of the intermediary to enforce the Fund’s excessive trading policy. However, there can be no assurance that an intermediary will cooperate in all instances. Certain intermediaries may not presently possess the same operational capabilities to track the number of purchase, redemption or exchange orders made by an individual investor as the Funds, or they may lack such capabilities entirely. Certain intermediaries may possess other capabilities to deter short-term or excessive trading upon which the Funds may rely. In general, the Funds cannot eliminate the possibility that short-term or excessive trading activity will occur in the Funds.

Each Fund also reserves the right to restrict the account of any investor with respect to purchase orders or the purchase portion of exchange orders, without prior notice, if the trading activity in the account is determined to be disruptive to the Fund. To minimize harm to the Funds and their shareholders, each Fund may, at the Fund’s sole discretion, exercise these rights if an investor has a history of excessive or disruptive trading. In making this judgment, the Fund may consider trading done in multiple accounts under common ownership or control. Such restriction typically is placed in the account immediately after such disruptive trading is determined to be occurring.

Excessive trading may present risks to the Funds’ long-term shareholders. Excessive trading into and out of a Fund can be disruptive to the portfolio, including with respect to the implementation of investment strategies. Excessive trading also may create taxable gains to remaining Fund shareholders and may increase Fund expenses, which may negatively impact investment returns for remaining shareholders.

Funds that invest in foreign securities may be at a greater risk for excessive trading. Some investors may seek to profit from the fact that foreign markets or exchanges normally close earlier in the day than do U.S. markets or exchanges. These investors may seek to engage in a practice known as pricing arbitrage to take advantage of information that becomes available after the close of the foreign markets or exchanges but before the Fund prices its shares, which may affect the prices of the foreign securities held by a Fund. Alternatively, some investors may attempt to benefit from stale pricing — when trading in a security held by a Fund is halted and does not resume prior to the time the Fund calculates its NAV. To the extent that a Fund does not accurately value securities, short-term arbitrage traders may dilute the Fund’s NAV, which may negatively impact long-term shareholders. Although

the Funds have adopted policies and procedures intended to reduce their exposure to price arbitrage, stale pricing and other potential pricing inefficiencies, the Funds cannot entirely eliminate the potential for short-term arbitrage trades to dilute the value of Fund shares.

The Funds’ policy is against trading of Fund shares by Fund shareholders that is disruptive to the management of a Fund. In analyzing whether trading is disruptive, the Funds will consider the purpose of the trades, the effects on the Fund’s portfolio and shareholders, and the impact of any costs or administrative charges it may incur (net of any reimbursement by the shareholder). For certain redemption and reinvestment transactions in which the investment adviser or its affiliates may engage, see page 51 of the statement of additional information.

The Funds’ policy is against frequent purchases and redemptions of a Fund’s shares that are disruptive to the Fund’s portfolio. The Funds attempt to detect and deter excessive trading through the following methods:

Although the Funds will take steps to detect and deter abusive trading pursuant to the policies and procedures approved by the board of trustees, there are no assurances that these policies and procedures will be effective in limiting excessive trading in all circumstances. For example, the Funds may be unable to completely eliminate the possibility of excessive trading in certain omnibus accounts and other accounts traded through intermediaries as discussed in the “Transaction restrictions” section.

The Funds’ policies and procedures regarding excessive trading may be modified by the Board of Trustees at any time.

You may receive two kinds of distributions from a Fund: dividends and capital gains distributions. Unless you requested on the account application or in writing that distributions be made in cash, all dividends and capital gains distributions are paid by crediting you with additional Fund shares of the same class you already own. In addition, under the same shareholder account registration and within the same share class, dividends and distributions from one Fund may be reinvested into another Fund, with this receiving Fund account being subject to the minimum initial investment requirements. These shares are valued at the next NAV per share that is computed after the dividend or distribution date. There is no sales charge applied. Dividend Growth Fund declares and pays dividends from net investment income quarterly. Mid Cap Growth Fund declares and pays dividends from net income annually. Net realized long-term capital gains, if any, are paid to shareholders by each Fund at least annually.

If a dividend check is returned undeliverable, or if a check remains outstanding for six months, the Fund reserves the right to reinvest those dividends in additional shares of that Fund at the current NAV and to designate the account as a dividend reinvestment account.

You may realize a capital gain or capital loss when you redeem or exchange shares. The federal tax treatment will depend on how long you owned the shares and on your individual tax position. Distributions, whether received in cash or reinvested in additional Fund shares, are subject to federal income tax and may be subject to state or local taxes. You may be subject to state and local taxes on your investment in a Fund, depending on the laws of your home state and locality.

The dividends and distributions paid by a Fund are subject to taxation as of the date of payment, except for those distributions declared in October, November or December and paid in January of the next year. Such a distribution will be treated as though it were received on December 31 of the year in which it is declared.

You may be taxed on dividends from net investment income and capital gains distributions at different rates depending on your tax situation. Dividends paid by a Fund from net investment income generally are taxable to you as ordinary income, unless paid from “qualified dividend income,” as described below. Federal taxes on distributions of capital gains by a Fund are determined by how long the Fund owned the investments that generated the gains, rather than how long you have owned your shares. Distributions of gains from investments that a Fund owned for more than one year will generally be taxable to you as long-term capital gains. Distributions of gains from investments that a Fund owned for one year or less will generally be taxable to you as ordinary income. Annually, the Funds will advise you of the source of your distributions for tax purposes.

A portion of the dividends from net investment income paid by Funds that invest primarily in equity securities may be eligible for the reduced rate applicable to “qualified dividend income,” provided that the recipient of the dividend is an individual and that certain holding period requirements are met. No assurance can be given as to what portion of the dividends paid by a Fund will consist of “qualified dividend income.”

A Fund may be required to withhold federal income tax (“backup withholding”) from payments to you if:

These certifications are contained in the application that you complete and return when you open an account. The Fund must promptly pay to the IRS all amounts withheld. Therefore, it is usually not possible for the Fund to reimburse you for amounts withheld. You may, however, claim the amount withheld as a credit on your federal income tax return.

Each shareholder of a Fund receives quarterly account statements showing transactions in Fund shares, with a balance denominated in Fund shares. A confirmation will be sent to the shareholder upon purchase, redemption, or change of shareholder address (sent to both the former and the new address).

You may use the Funds as investments for your IRA, profit sharing plan, pension plan, Section 401(k) plan, Section 403(b)(7) plan in the case of employees of public school systems and certain non-profit organizations, and certain other qualified plans. A master IRA plan and information regarding plan administration, fees, and other details are available from us or your plan administrator.

The Funds reduce the number of duplicate prospectuses and annual and semiannual reports you receive by sending only one copy of each to those addresses shared by two or more accounts. Call us at 800.582.6959 or write to us at the CALAMOS FAMILY OF FUNDS, c/o U.S. Bancorp Fund Services, LLC, P.O. Box 701, Milwaukee, WI 53201 if you want to receive individual copies of these documents. The Funds will begin sending you individual copies within 30 days of your request.

Certain of the Funds have adopted non-fundamental operating policies that require at least 80% of the Fund’s assets (net assets plus the amount of any borrowings for investment purposes) to be invested, under normal circumstances, in securities of the type suggested by the Fund’s name. Although these requirements may be changed by the board of trustees without shareholder approval, a Fund will notify shareholders at least 60 days prior to any change in its 80% policy.

Your mutual fund account may be transferred to your State of residence if no activity occurs within your account during the “inactivity period” specified in your State’s abandoned property laws.

When this prospectus was prepared, the Fund had not yet commenced operations and had no financial highlights to report.

If you would like more information about the Funds, the following resources are available upon request, free of charge.

Additional information about the Funds’ investments will be available in the Funds’ semiannual and annual reports to shareholders.

The Statement of Additional Information provides more detailed information about the Funds and, except for the information in the section entitled “Financial Statements,” is incorporated into this prospectus by reference.

Copies of the reports and the Statement of Additional Information are available, without charge, upon request, by calling 800.582.6959 or by visiting the Funds’ website at www.calamos.com. You can request other information and discuss your questions about the Funds by contacting Calamos Financial Services LLC at:

Calamos Financial Services LLC

2020 Calamos Court

Naperville, Illinois 60563

Telephone: 800.582.6959

You can review the Funds’ reports and Statement of Additional Information at the Public Reference Room of the Securities and Exchange Commission. You can get text-only copies for free from the EDGAR database on the Commission’s Internet website at http://www.sec.gov, or for a duplicating fee by calling or writing to:

Public Reference Section of the Commission

Washington, D.C. 20549-0102

Telephone: 202.551.8090

E-mail: publicinfo@sec.gov

FOR 24 HOUR AUTOMATED

SHAREHOLDER ASSISTANCE

800.823.7386

TO OBTAIN INFORMATION

ABOUT YOUR INVESTMENTS

800.582.6959

VISIT OUR WEB-SITE

www.calamos.com

INVESTMENT ADVISER

Calamos Advisors LLC

2020 Calamos Court

Naperville, IL 60563

TRANSFER AGENT

US Bancorp Fund Services, LLC

615 E. Michigan St. 3rd floor

Milwaukee, WI 53202

INDEPENDENT REGISTERED PUBLIC

ACCOUNTING FIRM

[ ]

Chicago, IL

LEGAL COUNSEL

K&L Gates LLP

Chicago, IL

Washington, DC