FORM OF LOCK‑UP AGREEMENT
TO BE DELIVERED PURSUANT TO SECTION 5(j)
October [•], 2011
Citigroup Global Markets Inc.
Deutsche Bank Securities Inc.
J.P. Morgan Securities LLC
c/o Citigroup Global Markets Inc.
388 Greenwich Street
New York, NY 10013
As Representatives of the several Underwriters
Proposed Public Offering by American Capital Agency Corp.
The undersigned, an officer and/or director or the manager of American Capital Agency Corp., a Delaware corporation (the “Company”), understands that Citigroup Global Markets Inc., Deutsche Bank Securities Inc. and J.P. Morgan Securities LLC (in such capacity, the “Representatives”) propose to enter into an Underwriting Agreement (the “Underwriting Agreement”) with the Company and American Capital AGNC Management, LLC, a Delaware limited liability company and the manager of the Company (the “Manager”), providing for the public offering of shares of the Company's common stock, $0.01 par value per share (“Common Stock”). In recognition of the benefit that such an offering will confer upon the undersigned as an officer and/or director or the manager of the Company, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned agrees with the Representatives that, during a period of 30 days following the date of the Underwriting Agreement, the undersigned will not, without the prior written consent of the Representatives, directly or indirectly, (i) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant for the sale of, or otherwise dispose of or transfer any of the shares of Common Stock or any securities convertible into or exchangeable or exercisable for shares of Common Stock, whether now owned or hereafter acquired by the undersigned or with respect to which the undersigned has or hereafter acquires the power of disposition, or file, or cause to be filed, any registration statement under the Securities Act of 1933, as amended, with respect to any of the foregoing (collectively, the “Lock‑Up Securities”) or (ii) enter into any swap or any other agreement or any transaction that transfers, in whole or