(NYSE: GBAB) Guggenheim Build America Bonds Managed Duration Trust (the “Trust”), a closed-end management investment company, announces that it is increasing its monthly dividend to $0.1348 per share, effective with its December 2012 dividend. The increased dividend compares to $0.1322 per share for the Trust’s most recent dividend. This increased dividend represents a distribution rate of 6.96% based upon the closing market price of $23.25 on November 30, 2012. The December 2012 dividend will be paid on December 31, 2012 to shareholders of record as of December 14, 2012 with an ex-dividend date of December 12, 2012. For additional commentary, news, portfolio holdings and other regularly updated information, please visit the Trust’s website at www.guggenheiminvestments.com. Past performance is not indicative of future performance. If it is determined that a notification is required, pursuant to Section 19(a) of the Investment Company Act of 1940, as amended, such notice will be posted to the Trust’s website after the close of business three business days prior to the payable date. Distributions may be comprised of sources other than income, which may not reflect actual Trust performance.About Guggenheim Investments Guggenheim Investments represents the investment management division of Guggenheim Partners (“Guggenheim”), which consists of investment managers with approximately $137 billion in combined total assets*. Collectively, Guggenheim Investments has a long, distinguished history of serving institutional investors, ultra-high-net-worth individuals, family offices and financial intermediaries. Guggenheim Investments offers clients a wide range of differentiated capabilities built on a proven commitment to investment excellence. Guggenheim Investments has offices in Chicago, New York City and Santa Monica, along with a global network of offices throughout the United States, Europe, and Asia. Guggenheim Investments is comprised of several investment management entities within Guggenheim Partners, which includes Guggenheim Funds Distributors, LLC and Guggenheim Funds Investment Advisors, LLC (together, “Guggenheim Funds”) . Guggenheim Funds Investment Advisors, LLC serves as Investment Adviser for GBAB. *The total asset figure is as of 09/30/2012 and includes $9.56B of leverage for Assets Under Management and $0.83B of leverage for Serviced Assets. Total assets include assets from Security Investors, LLC, Guggenheim Partners Investment Management, LLC (“GPIM”, formerly known as Guggenheim Partners Asset Management, LLC; GPIM assets also include all assets from Guggenheim Investment Management, LLC which were transferred as of 06/30/2012), Guggenheim Funds Investment Advisors and its affiliated entities, and some business units including Guggenheim Real Estate, LLC, Guggenheim Aviation, GS GAMMA Advisors, LLC, Guggenheim Partners Europe Limited, Transparent Value Advisors, LLC, and Guggenheim Partners India Management. Values from some funds are based upon prior periods.