0001079575 2011-04-30 2012-04-29 0001079575 cit2:S000006427Member 2011-04-30 2012-04-29 Other 2012-04-29 2011-12-31 CALAMOS ADVISORS TRUST/IL 0001079575 false 2012-12-19 2012-12-19 CALAMOS ® GROWTH AND INCOME PORTFOLIO Supplement dated December 19, 2012 to the Prospectus and Statement of Additional Information dated April 29, 2012 as previously supplement on August 31, 2012 The Principal Investment Strategies Section on Page 4 of the Prospectus shall be replaced in its entirety as follows: Principal Investment Strategies The Portfolio invests primarily in a diversified portfolio of convertible (including synthetic convertible instruments), equity and fixed-income securities of U.S. companies without regard to market capitalization. In pursuing its investment objective, the Portfolio attempts to utilize these different types of securities to strike, in the investment advisers opinion, the appropriate balance between risk and return in terms of growth and income. As the market environment changes, portfolio securities may change in an attempt to achieve a relatively consistent risk level over time. The average term to maturity of the convertible and fixed-income securities purchased by the Portfolio will typically range from five to ten years. The Portfolios investment adviser seeks to lower the risks of investing in stocks by using a top-down approach of diversification by company, industry, sector, country and currency and focusing on macro-level investment themes. Consistent with the Funds investment objective and principal investment strategies the Funds investment adviser attempts to lower market risk by selecting and investing in securities that it believes will exhibit less volatility and will provide greater capital exposure and more consistent returns than the market as a whole CALAMOS ® GROWTH AND INCOME PORTFOLIO Supplement dated December 19, 2012 to the Prospectus and Statement of Additional Information dated April 29, 2012 as previously supplement on August 31, 2012 The Principal Investment Strategies Section on Page 4 of the Prospectus shall be replaced in its entirety as follows: Principal Investment Strategies The Portfolio invests primarily in a diversified portfolio of convertible (including synthetic convertible instruments), equity and fixed-income securities of U.S. companies without regard to market capitalization. In pursuing its investment objective, the Portfolio attempts to utilize these different types of securities to strike, in the investment advisers opinion, the appropriate balance between risk and return in terms of growth and income. As the market environment changes, portfolio securities may change in an attempt to achieve a relatively consistent risk level over time. The average term to maturity of the convertible and fixed-income securities purchased by the Portfolio will typically range from five to ten years. The Portfolios investment adviser seeks to lower the risks of investing in stocks by using a top-down approach of diversification by company, industry, sector, country and currency and focusing on macro-level investment themes. Consistent with the Funds investment objective and principal investment strategies the Funds investment adviser attempts to lower market risk by selecting and investing in securities that it believes will exhibit less volatility and will provide greater capital exposure and more consistent returns than the market as a whole Principal Investment Strategies The Portfolio invests primarily in a diversified portfolio of convertible (including synthetic convertible instruments), equity and fixed-income securities of U.S. companies without regard to market capitalization. In pursuing its investment objective, the Portfolio attempts to utilize these different types of securities to strike, in the investment advisers opinion, the appropriate balance between risk and return in terms of growth and income. As the market environment changes, portfolio securities may change in an attempt to achieve a relatively consistent risk level over time. The average term to maturity of the convertible and fixed-income securities purchased by the Portfolio will typically range from five to ten years. The Portfolios investment adviser seeks to lower the risks of investing in stocks by using a top-down approach of diversification by company, industry, sector, country and currency and focusing on macro-level investment themes. Consistent with the Funds investment objective and principal investment strategies the Funds investment adviser attempts to lower market risk by selecting and investing in securities that it believes will exhibit less volatility and will provide greater capital exposure and more consistent returns than the market as a whole