American Capital Agency Corp. is a real estate investment trust (REIT). The Company primarily invests on a leveraged basis in agency mortgage-backed securities (agency MBS). The Company's investments consist of residential mortgage pass-through securities and collateralized mortgage obligations (CMOs) for which the principal and interest payments are guaranteed by a government-sponsored enterprise, such as the Federal National Mortgage Association (Fannie Mae) and the Federal Home Loan Mortgage Corporation (Freddie Mac), or by the United States Government agency, such as the Government National Mortgage Association (Ginnie Mae) (collectively, GSEs). The Company also invests in other assets related to agency securities and approximately 10% of its assets in AAA non-agency and commercial mortgage-backed securities (collectively, AAA non-agency MBS). The Company is externally managed by American Capital AGNC Management, LLC, an affiliate of American Capital, Ltd.