424B5

This is a public offering of common stock of American Capital Agency Corp. We are offering 62,000,000 shares of common stock. Our common stock is listed on The NASDAQ Global Select Market under the symbol “AGNC.” On March 6, 2012, the last reported sale price of our common stock was $29.85 per share.

The underwriters have agreed to purchase our common stock from us at a price of $29.00 per share, which will result in approximately $1.80 billion of total net proceeds to us. The underwriters may offer our common stock in transactions on The NASDAQ Global Select Market, in the over-the-counter market or through negotiated transactions at market prices or at negotiated prices. See “Underwriting.”

We have granted the underwriters a 30-day option to purchase up to 9,150,000 additional shares of common stock at a price of $29.00 per share, to cover overallotments.

Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page S-4 of this prospectus supplement and in the documents incorporated by reference in this prospectus supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The underwriters expect to deliver the shares of common stock on or about March 13, 2012.

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and the securities offered hereby, and also adds to and updates information contained in the accompanying base prospectus and the documents incorporated by reference into this prospectus supplement and the base prospectus. The second part, the base prospectus, gives more general information and disclosure. When we refer only to the prospectus, we are referring to both parts combined, and when we refer to the accompanying prospectus, we are referring to the base prospectus.

If there is any inconsistency between information in or incorporated by reference into the base prospectus and information in or incorporated by reference into this prospectus supplement, you should rely only on the information contained in or incorporated by reference into this prospectus supplement. This prospectus supplement, the accompanying prospectus and the documents incorporated into each by reference include important information about us, the common stock being offered and other information you should know before investing. You should read this prospectus supplement and the accompanying prospectus together with the additional information described under the heading, “Where You Can Find More Information” before investing in our common stock.

You should rely only on the information contained in or incorporated by reference into this prospectus supplement and the accompanying prospectus. We have not, and the underwriters have not, authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale thereof is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus and the documents incorporated into each by reference is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed since those dates.

This prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, contain forward looking statements that are subject to risks and uncertainties. These forward looking statements include information about possible or assumed future results of our business and our financial condition, liquidity, results of operations, plans and objectives. They also include, among other things, statements concerning anticipated revenues, income or loss, capital expenditures, dividends, capital structure, or other financial terms, as well as statements regarding subjects that are forward looking by their nature, such as:

The forward looking statements are based on our beliefs, assumptions, and expectations of our future performance, taking into account the information currently available to us. These beliefs, assumptions, and expectations may change as a result of many possible events or factors, not all of which are known to us. If a change occurs, our business, financial condition, liquidity, and results of operations may vary materially from those expressed in our forward looking statements. You should carefully consider these risks when you make a decision concerning an investment in our common stock, along with the following factors, among others, that may cause actual results to vary from our forward looking statements:

When we use words such as “will likely result,” “plan,” “may,” “shall,” “believe,” “expect,” “anticipate,” “project,” “intend,” “estimate,” “goal,” “objective,” or similar expressions, we intend to identify forward looking statements. You should not place undue reliance on these forward looking statements, which apply only as of the date of this prospectus supplement. We do not intend to and we disclaim any duty or obligation to update or revise any industry information or forward looking statement set forth in this prospectus supplement to reflect new information, future events, or otherwise, except as required under U.S. federal securities laws.

SUMMARY

The following summary highlights information contained elsewhere or incorporated by reference in this prospectus supplement and the accompanying prospectus. It may not contain all of the information that is important to you. Before making a decision to invest in our common stock, you should carefully read this entire prospectus supplement and the accompanying prospectus, including the risks set forth under the caption “Risk Factors” in this prospectus supplement and in the documents incorporated by reference herein, and the information set forth under the caption “Where You Can Find More Information” on page S-29.

Except where the context suggests otherwise, all references to “we,” “our” and “us” in this prospectus supplement refer to American Capital Agency Corp. and its subsidiary. Unless indicated otherwise, the information in this prospectus supplement assumes that the underwriters’ overallotment option is not exercised.

Our Company

We have elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended. As long as we qualify as a REIT, we generally will not be subject to federal income taxes on our taxable income to the extent that we annually distribute all of our taxable income to stockholders.

We are externally managed by American Capital AGNC Management, LLC, which we refer to as our Manager. Our Manager is an indirect subsidiary of a wholly owned portfolio company of American Capital, Ltd., or American Capital, an investment company and alternative asset manager that is listed on The NASDAQ Global Select Market under the symbol “ACAS.” Because we have no employees, our Manager is responsible for administering our business activities and day-to-day operations, subject to the supervision of our Board of Directors.

Our principal objective is to preserve our net asset value while generating attractive risk-adjusted returns for distribution to our stockholders through regular quarterly dividends from our net interest income, which is the spread between the interest income earned on our interest-earning assets and the interest costs of our borrowings and hedging activities, and net realized gains and losses on our investments and other supplemental hedging activities. We fund our investments through short-term borrowings structured as repurchase agreements. Since our initial public offering on May 20, 2008, we have paid or declared dividends to our stockholders of $1.5 billion in the aggregate.

Recent Developments

On March 5, 2012, we filed a preliminary proxy statement with the SEC pursuant to which we are, among other things, requesting the approval of our stockholders to amend our Amended and Restated Certificate of Incorporation to increase the total authorized number of shares of common stock from 300,000,000 to 600,000,000 and the total authorized number of shares of preferred stock from 10,000,000 to 50,000,000.

Our at-the-market offering program enables us to publicly offer and sell, from time to time, up to an aggregate 26.2 million shares of our common stock in privately negotiated and/or at-the-market transactions pursuant to sales agreements with sales agents. During the period from January 1, 2012 through March 5, 2012, we sold 4.7 million shares of our common stock under our program with Mitsubishi UFJ Securities (USA), Inc. for net proceeds of $142.3 million.

THE OFFERING

Issuer

American Capital Agency Corp.

Common stock offered by us

62,000,000 shares (plus up to an additional 9,150,000 shares of common stock that we may issue and sell upon the exercise of the underwriters’ overallotment option in full).

Common stock to be outstanding after this offering

290,842,970 shares (or 299,992,970 shares if the underwriters exercise their overallotment option in full), based upon 228,842,970 shares of common stock outstanding as of March 6, 2012.⁽¹⁾

NASDAQ trading symbol

“AGNC”

Use of proceeds

We intend to use the net proceeds of this offering, in conjunction with borrowings under our master repurchase agreements, to buy agency securities and for general corporate purposes.

⁽¹⁾ Includes an aggregate of 25,500 shares of unvested restricted common stock that have been granted to our four independent directors under the American Capital Agency Corp. Equity Incentive Plan for Independent Directors as of March 6, 2012.

We estimate that the net proceeds to us from this offering of our common stock will be approximately $1.80 billion, or $2.06 billion if the underwriters’ overallotment option is exercised in full, after deducting estimated offering expenses payable by us.

We intend to use the net proceeds from this offering, in conjunction with borrowings under our master repurchase agreements, to buy agency securities and for general corporate purposes. Depending on the availability of our targeted investments in agency securities following the closing of this offering, we may temporarily invest the net proceeds in readily marketable, short-term, interest-bearing investments, including money market accounts, which are consistent with maintaining our qualification as a REIT. These temporary investments are expected to provide a lower net return than we hope to achieve from our targeted investments in agency securities.

Investing in our common stock involves a high degree of risk. You should carefully consider the risks described in the section entitled “Risk Factors” in our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q (which descriptions are incorporated by reference herein), as well as the other information contained or incorporated by reference in this prospectus supplement before making a decision to invest in our common stock. See “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference” below.

The following table sets forth the cash distributions declared per share of common stock during each fiscal quarter of our current fiscal year and our last fiscal year since our initial public offering on May 20, 2008.

Please see the section entitled “Federal Income Tax Considerations—Annual Distribution Requirements” beginning on page S-16 of this prospectus supplement.

The following table sets forth our capitalization as of December 31, 2011 (i) on a historical basis and (ii) as adjusted for the sale of 4.7 million shares of common stock sold under a Sales Agreement with Mitsubishi UFJ Securities (USA), Inc. for net proceeds of $142.3 million and as adjusted to reflect the sale of 62 million shares of common stock at an offering price of $29.00 per share in this offering and application of the estimated net proceeds as described under “Use of Proceeds,” after deducting estimated offering expenses payable by us. This presentation should be read in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2011 that we are incorporating by reference into this prospectus supplement and the accompanying prospectus.

⁽¹⁾ Assumes no exercise of the underwriters’ overallotment option to purchase up to an additional 9,150,000 shares of our common stock.

The following summary of certain U.S. Federal income tax considerations supersedes the discussion set forth under the heading “Federal Income Tax Considerations” in the accompanying prospectus and is for general information only and is not tax advice.

The following is a summary of the material U.S. federal income tax consequences of an investment in common stock of American Capital Agency Corp. For purposes of this section under the heading “Federal Income Tax Considerations,” references to “American Capital Agency Corp.,” “we,” “our” and “us” mean only American Capital Agency Corp. and not its subsidiaries or other lower-tier entities, except as otherwise indicated. This summary is based upon the Internal Revenue Code, the regulations promulgated by the U.S. Treasury Department (“Treasury”), rulings and other administrative pronouncements issued by the IRS, and judicial decisions, all as currently in effect, and all of which are subject to differing interpretations or to change, possibly with retroactive effect. No assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to any of the tax consequences described below. The summary is also based upon the assumption that we will operate American Capital Agency Corp. and its subsidiaries and affiliated entities in accordance with their applicable organizational documents or partnership agreements. This summary is for general information only and is not tax advice. It does not purport to discuss all aspects of U.S. federal income taxation that may be important to a particular investor in light of its investment or tax circumstances or to investors subject to special tax rules, such as:

This summary assumes that investors will hold their common stock as a capital asset, which generally means as property held for investment.

THE FEDERAL INCOME TAX TREATMENT OF HOLDERS OF OUR COMMON STOCK DEPENDS IN SOME INSTANCES ON DETERMINATIONS OF FACT AND INTERPRETATIONS OF COMPLEX PROVISIONS OF U.S. FEDERAL INCOME TAX LAW FOR WHICH NO CLEAR PRECEDENT OR AUTHORITY MAY BE AVAILABLE. IN ADDITION, THE TAX CONSEQUENCES TO ANY PARTICULAR STOCKHOLDER OF HOLDING OUR COMMON STOCK WILL DEPEND ON THE STOCKHOLDER’S PARTICULAR TAX CIRCUMSTANCES. YOU ARE URGED TO CONSULT YOUR TAX ADVISOR REGARDING THE FEDERAL, STATE, LOCAL, AND FOREIGN INCOME AND OTHER TAX CONSEQUENCES TO YOU IN LIGHT OF YOUR PARTICULAR INVESTMENT OR TAX CIRCUMSTANCES OF ACQUIRING, HOLDING, EXCHANGING, OR OTHERWISE DISPOSING OF OUR COMMON STOCK.

We have elected to be taxed as a REIT, commencing with our initial taxable year ended December 31, 2008. We believe that we have been organized and have operated in such a manner that permits us to satisfy the requirements for taxation as a REIT under the applicable provisions of the Internal Revenue Code.

The law firm of Skadden, Arps, Slate, Meagher & Flom LLP has acted as our tax counsel in connection with this offering of our common stock. In connection with this offering of our common stock, we expect to receive an opinion of Skadden, Arps, Slate, Meagher & Flom LLP to the effect that, commencing with our initial taxable year, we have been organized and operated in conformity with the requirements for qualification and taxation as a REIT under the Internal Revenue Code, and that our actual method of operation has enabled, and our proposed method of operation will continue to enable, us to meet the requirements for qualification and taxation as a REIT. It must be emphasized that the opinion of Skadden, Arps, Slate, Meagher & Flom LLP will be based on various assumptions relating to our organization and operation and will be conditioned upon fact-based representations and covenants made by our management regarding our organization, assets, and income, and the present and future conduct of our business operations. While we intend to operate so that we continue to qualify as a REIT, given the highly complex nature of the rules governing REITs, the ongoing importance of factual determinations, and the possibility of future changes in our circumstances, no assurance can be given by Skadden, Arps, Slate, Meagher & Flom LLP or by us that we will qualify as a REIT for any particular year. The opinion will be expressed as of the date issued and will not cover subsequent periods. Skadden, Arps, Slate, Meagher & Flom LLP will have no obligation to advise us or our stockholders of any subsequent change in the matters stated, represented or assumed, or of any subsequent change in the applicable law. You should be aware that opinions of counsel are not binding on the IRS, and no assurance can be given that the IRS will not challenge the conclusions set forth in such opinions.

While we intend to operate so that we will continue to qualify as a REIT, given the highly complex nature of the rules governing REITs, the ongoing importance of factual determinations, and the possibility of future changes in our circumstances, no assurance can be given by us that we will qualify as a REIT for any particular year. Qualification and taxation as a REIT depends on our ability to meet on a continuing basis, through actual operating results, distribution levels, and diversity of stock and asset ownership, various qualification requirements imposed upon REITs by the Internal Revenue Code. Our ability to qualify as a REIT also requires that we satisfy certain asset tests, some of which depend upon the fair market values of assets that we own directly or indirectly. Such values may not be susceptible to a precise determination. Accordingly, no assurance can be given that the actual results of our operations for any taxable year will satisfy such requirements for qualification and taxation as a REIT.

As indicated above, our qualification and taxation as a REIT depends upon our ability to meet, on a continuing basis, various qualification requirements imposed upon REITs by the Internal Revenue Code. The material qualification requirements are summarized below under “—Requirements for Qualification—General.” While we intend to operate so that we continue to qualify as a REIT, no assurance can be given that the IRS will not challenge our qualification, or that we will be able to operate in accordance with the REIT requirements in the future. See “—Failure to Qualify.”

Provided that we qualify as a REIT, generally we will be entitled to a deduction for dividends that we pay and therefore will not be subject to federal corporate income tax on our taxable income that is currently distributed to our stockholders. This treatment substantially eliminates the “double taxation” at the corporate and stockholder levels that generally results from investment in a corporation. In general, the income that we generate is taxed only at the stockholder level upon a distribution of dividends to our stockholders.

For tax years through 2012, most domestic stockholders that are individuals, trusts or estates are taxed on corporate dividends at a maximum rate of 15% (the same as long-term capital gains). With limited exceptions,

however, dividends from us or from other entities that are taxed as REITs are generally not eligible for this rate and will continue to be taxed at rates applicable to ordinary income, which will be as high as 35% through 2012, and as high as 39.6% thereafter. See “—Taxation of Stockholders—Taxation of Taxable Domestic Stockholders—Distributions.”

Any net operating losses, foreign tax credits and other tax attributes generally do not pass through to our stockholders, subject to special rules for certain items such as the capital gains that we recognize. See “—Taxation of Stockholders—Taxation of Taxable Domestic Stockholders—Distributions.”

In any year in which we qualify as a REIT, we will nonetheless be subject to federal tax in the following circumstances:

In addition, we and our subsidiaries may be subject to a variety of taxes, including payroll taxes and state, local, and foreign income, property and other taxes on our assets and operations. We could also be subject to tax in situations and on transactions not presently contemplated.

The Internal Revenue Code defines a REIT as a corporation, trust or association:

The Internal Revenue Code provides that conditions (1) through (4) must be met during the entire taxable year, and that condition (5) must be met during at least 335 days of a taxable year of 12 months, or during a proportionate part of a shorter taxable year. Conditions (5) and (6) need not be met during a corporation’s initial tax year as a REIT (which, in our case, was 2008). Our amended and restated articles of incorporation provides restrictions regarding the ownership and transfers of our stock, which are intended to assist us in satisfying the stock ownership requirements described in conditions (5) and (6) above.

To monitor compliance with the stock ownership requirements, we generally are required to maintain records regarding the actual ownership of our stocks. To do so, we must demand written statements each year from the record holders of significant percentages of our stock pursuant to which the record holders must disclose the actual owners of the stock (i.e., the persons required to include our dividends in their gross income). We must maintain a list of those persons failing or refusing to comply with this demand as part of our records. We could be subject to monetary penalties if we fail to comply with these record-keeping requirements. If you fail or refuse to comply with the demands, you will be required by Treasury regulations to submit a statement with your tax return disclosing your actual ownership of our stock and other information.

In addition, a corporation generally may not elect to become a REIT unless its taxable year is the calendar year. We have adopted December 31 as our year-end, and thereby satisfy this requirement.

of the violation. In addition, certain provisions of the Internal Revenue Code extend similar relief in the case of certain violations of the REIT asset requirements (see “—Asset Tests” below) and other REIT requirements, again provided that the violation is due to reasonable cause and not willful neglect, and other conditions are met, including the payment of a penalty tax. If we fail to satisfy any of the various REIT requirements, there can be no assurance that these relief provisions would be available to enable us to maintain our qualification as a REIT, and, if such relief provisions are available, the amount of any resultant penalty tax could be substantial.

Ownership of Partnership Interests. If we are a partner in an entity that is treated as a partnership for federal income tax purposes, Treasury regulations provide that we are deemed to own our proportionate share of the partnership’s assets, and to earn our proportionate share of the partnership’s income, for purposes of the asset and gross income tests applicable to REITs. Our proportionate share of a partnership’s assets and income is based on our capital interest in the partnership (except that for purposes of the 10% value test, described below, our proportionate share of the partnership’s assets is based on our proportionate interest in the equity and certain debt securities issued by the partnership). In addition, the assets and gross income of the partnership are deemed to retain the same character in our hands. Thus, our proportionate share of the assets and items of income of any of our subsidiary partnerships will be treated as our assets and items of income for purposes of applying the REIT requirements.

Disregarded Subsidiaries. If we own a corporate subsidiary that is a “qualified REIT subsidiary,” that subsidiary is generally disregarded for federal income tax purposes, and all of the subsidiary’s assets, liabilities and items of income, deduction and credit are treated as our assets, liabilities and items of income, deduction and credit, including for purposes of the gross income and asset tests applicable to REITs. A qualified REIT subsidiary is any corporation, other than a TRS (as described below), that is directly or indirectly wholly-owned by a REIT. Other entities that are wholly-owned by us, including single member limited liability companies that have not elected to be taxed as corporations for federal income tax purposes, are also generally disregarded as separate entities for federal income tax purposes, including for purposes of the REIT income and asset tests. Disregarded subsidiaries, along with any partnerships in which we hold an equity interest, are sometimes referred to herein as “pass-through subsidiaries.”

In the event that a disregarded subsidiary of ours ceases to be wholly-owned—for example, if any equity interest in the subsidiary is acquired by a person other than us or another disregarded subsidiary of ours—the subsidiary’s separate existence would no longer be disregarded for federal income tax purposes. Instead, the subsidiary would have multiple owners and would be treated as either a partnership or a taxable corporation. Such an event could, depending on the circumstances, adversely affect our ability to satisfy the various asset and gross income requirements applicable to REITs, including the requirement that REITs generally may not own, directly or indirectly, more than 10% of the securities of another corporation. See “—Asset Tests” and “—Income Tests.”

Taxable Subsidiaries. In general, we may jointly elect with a subsidiary corporation, whether or not wholly-owned, to treat such subsidiary corporation as a TRS. We generally may not own more than 10% of the securities of a taxable corporation, as measured by voting power or value, unless we and such corporation elect to treat such corporation as a TRS. The separate existence of a TRS or other taxable corporation is not ignored for federal income tax purposes. Accordingly, our TRS or other taxable corporation generally is subject to corporate income tax on its earnings, which may reduce the cash flow that we and our subsidiaries generate in the aggregate, and may reduce our ability to make distributions to our stockholders.

income of TRSs or other taxable subsidiary corporations in determining our compliance with the REIT requirements, we may use such entities to undertake indirectly activities that the REIT rules might otherwise preclude us from doing directly or through pass-through subsidiaries. For example, we may use TRSs or other taxable subsidiary corporations to conduct activities that give rise to certain categories of income such as management fees or to conduct activities that, if conducted by us directly, would be treated in our hands as prohibited transactions.

The TRS rules limit the deductibility of interest paid or accrued by a TRS to its parent REIT to assure that the TRS is subject to an appropriate level of corporate taxation. Further, the rules impose a 100% excise tax on transactions between a TRS and its parent REIT or the REIT’s tenants that are not conducted on an arm’s-length basis. We intend that all of our transactions with our TRSs will be conducted on an arm’s-length basis.

In order to continue to qualify as a REIT, we must satisfy two gross income requirements on an annual basis. First, at least 75% of our gross income for each taxable year, excluding gross income from sales of inventory or dealer property in “prohibited transactions” and certain hedging transactions, generally must be derived from investments relating to real property or mortgages on real property, including interest income derived from mortgage loans secured by real property (including, generally, agency securities and certain types of mortgage-backed securities), “rents from real property,” dividends received from other REITs, and gains from the sale of real estate assets, as well as specified income from temporary investments. Second, at least 95% of our gross income in each taxable year, excluding gross income from prohibited transactions and certain hedging transactions, must be derived from some combination of income that qualifies under the 75% gross income test described above, as well as other dividends, interest, and gain from the sale or disposition of stock or securities, which need not have any relation to real property. Income and gain from hedging transactions entered into after July 30, 2008 will be excluded from both the numerator and the denominator for purposes of both the 75% and 95% gross income tests.

Interest income constitutes qualifying mortgage interest for purposes of the 75% gross income test (as described above) to the extent that the obligation upon which such interest is paid is secured by a mortgage on real property. If we receive interest income with respect to a mortgage loan that is secured by both real property and other property, and the highest principal amount of the loan outstanding during a taxable year exceeds the fair market value of the real property on the date that we acquired or originated the mortgage loan, the interest income will be apportioned between the real property and the other collateral, and our income from the arrangement will qualify for purposes of the 75% gross income test only to the extent that the interest is allocable to the real property. Even if a loan is not secured by real property, or is undersecured, the income that it generates may nonetheless qualify for purposes of the 95% gross income test.

We intend to continue to invest exclusively in agency securities that are either pass-through certificates or collateralized mortgage obligations (“CMOs”). We expect that the agency securities will be treated either as interests in a grantor trust or as interests in a real estate mortgage investment conduit (“REMIC”) for federal income tax purposes and that all interest income from our agency securities will be qualifying income for the 95% gross income test. In the case of an agency securities treated as interests in grantor trusts, we would be treated as owning an undivided beneficial ownership interest in the mortgage loans held by the grantor trust. The interest on such mortgage loans would be qualifying income for purposes of the 75% gross income test to the extent that the obligation is secured by real property, as discussed above. In the case of agency securities treated as interests in a REMIC, income derived from REMIC interests will generally be treated as qualifying income for purposes of the 75% and 95% gross income tests. If less than 95% of the assets of the REMIC are real estate assets, however, then only a proportionate part of our interest in the REMIC and income derived from the interest will qualify for purposes of the 75% gross income test. In addition, some REMIC securitizations include imbedded interest swap or cap contracts or other derivative instruments that potentially could produce non-qualifying income for the holder of the related REMIC securities. We expect that substantially all of our income from agency securities will be qualifying income for purposes of the REIT gross income tests.

We purchase and sell agency securities through “to-be-announced” forward contracts (“TBAs”) and recognize income or gains from the disposition of those TBAs, through dollar roll transactions or otherwise, and may continue to do so in the future. While there is no direct authority with respect to the qualification of income or gains from dispositions of TBAs as gains from the sale of real property (including interests in real property and interests in mortgages on real property) or other qualifying income for purposes of the 75% gross income test, we treat income and gains from our TBAs as qualifying income for purposes of the 75% gross income test, based on an opinion of Skadden, Arps, Slate, Meagher & Flom LLP substantially to the effect that, for purposes of the 75% REIT gross income test, any gain recognized by us in connection with the settlement of our TBAs should be treated as gain from the sale or disposition of the underlying agency securities. Opinions of counsel are not binding on the IRS, and no assurance can be given that the IRS will not successfully challenge the conclusions set forth in such opinions. In addition, as noted above, the opinion of Skadden, Arps, Slate, Meagher & Flom LLP is based on various assumptions relating to our TBAs and is conditioned upon fact-based representations and covenants made by our management regarding our TBAs. No assurance can be given that the IRS would not assert that such income is not qualifying income. If the IRS were to successfully challenge the opinion of Skadden, Arps, Slate, Meagher & Flom LLP, we could be subject to a penalty tax or we could fail to qualify as a REIT if a sufficient portion of our income consists of income or gains from the disposition of TBAs.

Rents received by us, if any, will qualify as “rents from real property” in satisfying the gross income requirements described above only if several conditions are met. If rent is partly attributable to personal property leased in connection with a lease of real property, the portion of the rent that is attributable to the personal property will not qualify as “rents from real property” unless it constitutes 15% or less of the total rent received under the lease. In addition, the amount of rent must not be based in whole or in part on the income or profits of any person. Amounts received as rent, however, generally will not be excluded from rents from real property solely by reason of being based on fixed percentages of gross receipts or sales. Also, rental income will qualify as rents from real property only to the extent that we do not directly or constructively hold a 10% or greater interest, as measured by vote or value, in the lessee’s equity.

We may directly or indirectly receive distributions from our TRS or other corporations that are not REITs or qualified REIT subsidiaries. These distributions generally are treated as dividend income to the extent of the earnings and profits of the distributing corporation. Such distributions will generally constitute qualifying income for purposes of the 95% gross income test, but not for purposes of the 75% gross income test. Any dividends that we receive from a REIT, however, will be qualifying income for purposes of both the 95% and 75% gross income tests.

Fees will generally be qualifying income for purposes of both the 75% and 95% gross income tests if they are received in consideration for entering into an agreement to make a loan secured by real property and the fees are not determined by income and profits. Other fees generally will not be qualifying income for purposes of either gross income test and will not be favorably counted for purposes of either gross income test. Any fees earned by our TRS will not be included for purposes of the gross income tests. Any income or gain that we or our pass-through subsidiaries derive from instruments that hedge certain risks, such as the risk of changes in interest rates, will be excluded from gross income for purposes of both the 75% and 95% gross income tests, provided that specified requirements are met, including the requirement that the instrument is entered into during the ordinary course of our business, the instrument hedges risks associated with indebtedness issued by us or our pass-through subsidiary that is incurred to acquire or carry “real estate assets” (as described below under “—Asset Tests”), and the instrument is properly identified as a hedge along with the risk that it hedges within prescribed time periods. Income and gain from all other hedging transactions will not be qualifying income for either the 95% or 75% gross income test.

and (2) following our identification of the failure to meet the 75% or 95% gross income test for any taxable year, we file a schedule with the IRS setting forth each item of our gross income for purposes of the 75% or 95% gross income test for such taxable year in accordance with Treasury regulations yet to be issued. It is not possible to state whether we would be entitled to the benefit of these relief provisions in all circumstances. If these relief provisions are inapplicable to a particular set of circumstances, we will not qualify as a REIT. As discussed above under “—Taxation of REITs in General,” even where these relief provisions apply, the Internal Revenue Code imposes a tax based upon the amount by which we fail to satisfy the particular gross income test.

Under The Housing and Economic Recovery Tax Act of 2008, the Secretary of the Treasury has been given broad authority to determine whether particular items of gain or income recognized after July 30, 2008, qualify or not under the 75% and 95% gross income tests, or are to be excluded from the measure of gross income for such purposes.

At the close of each calendar quarter, we must also satisfy four tests relating to the nature of our assets. First, at least 75% of the value of our total assets must be represented by some combination of “real estate assets,” cash, cash items, U.S. government securities, and, under some circumstances, stock or debt instruments purchased with new capital. For this purpose, real estate assets include some kinds of mortgage-backed securities and mortgage loans, as well as interests in real property and stock of other corporations that qualify as REITs. Assets that do not qualify for purposes of the 75% asset test are subject to the additional asset tests described below.

Second, the value of any one issuer’s securities that we own may not exceed 5% of the value of our total assets.

Third, we may not own more than 10% of any one issuer’s outstanding securities, as measured by either voting power or value. The 5% and 10% asset tests do not apply to securities of TRSs and qualified REIT subsidiaries and the 10% asset test does not apply to “straight debt” having specified characteristics and to certain other securities described below. Solely for purposes of the 10% asset test, the determination of our interest in the assets of a partnership or limited liability company in which we own an interest will be based on our proportionate interest in any securities issued by the partnership or limited liability company, excluding for this purpose certain securities described in the Internal Revenue Code. Fourth, the aggregate value of all securities of TRSs that we hold may not exceed 25% (20% with respect to taxable years commencing prior to July 31, 2008) of the value of our total assets.

Notwithstanding the general rule, as noted above, that for purposes of the REIT income and asset tests we are treated as owning our proportionate share of the underlying assets of a subsidiary partnership, if we hold indebtedness issued by a partnership, the indebtedness will be subject to, and may cause a violation of, the asset tests unless the indebtedness is a qualifying mortgage asset or other conditions are met. Similarly, although stock of another REIT is a qualifying asset for purposes of the REIT asset tests, any non-mortgage debt that is issued by another REIT may not so qualify (such debt, however, will not be treated as “securities” for purposes of the 10% asset test, as explained below).

REIT and certain persons related to the REIT under attribution rules), (3) any obligation to pay rents from real property, (4) securities issued by governmental entities that are not dependent in whole or in part on the profits of (or payments made by) a non-governmental entity, (5) any security (including debt securities) issued by another REIT, and (6) any debt instrument issued by a partnership if the partnership’s income is of a nature that it would satisfy the 75% gross income test described above under “—Income Tests.” In applying the 10% asset test, a debt security issued by a partnership is not taken into account to the extent, if any, of the REIT’s proportionate interest in the equity and certain debt securities issued by that partnership.

We intend to continue to invest exclusively in agency securities that are either pass-through certificates or CMOs. We expect that the agency securities will be treated either as interests in grantor trusts or as interests in REMICs for federal income tax purposes. In the case of an agency securities treated as interests in grantor trusts, we would be treated as owning an undivided beneficial ownership interest in the mortgage loans held by the grantor trust. Such mortgage loans will generally qualify as real estate assets to the extent that they are secured by real property. We expect that substantially all of our agency securities treated as interests in grantor trust will qualify as real estate assets. In the case of agency securities treated as interests in a REMIC, such interests will generally qualify as real estate assets and income derived from REMIC interests will generally be treated as qualifying income for purposes of the REIT income tests described above. If less than 95% of the assets of a REMIC are real estate assets, however, then only a proportionate part of our interest in the REMIC and income derived from the interest will qualify for purposes of the REIT asset and income tests.

We intend to enter into sale and repurchase agreements under which we would nominally sell certain of our agency securities to a counterparty and simultaneously enter into an agreement to repurchase the sold assets in exchange for a purchase price that reflects a financing charge. We believe that we would be treated for REIT asset and income test purposes as the owner of the agency securities that are the subject of any such agreement notwithstanding that such agreements may transfer record ownership of the assets to the counterparty during the term of the agreement. It is possible, however, that the IRS could assert that we did not own the agency securities during the term of the sale and repurchase agreement, in which case we could fail to qualify as a REIT.

We purchase and sell agency securities through TBAs and may continue to do so in the future. While there is no direct authority with respect to the qualification of TBAs as real estate assets or Government securities for purposes of the 75% asset test, we treat our TBAs as qualifying assets for purposes of the REIT asset tests, based on an opinion of Skadden, Arps, Slate, Meagher & Flom LLP substantially to the effect that, for purposes of the REIT asset tests, our ownership of a TBA should be treated as ownership of the underlying agency securities. Opinions of counsel are not binding on the IRS, and no assurance can be given that the IRS will not successfully challenge the conclusions set forth in such opinions. In addition, as noted above, the opinion of Skadden, Arps, Slate, Meagher & Flom LLP is based on various assumptions relating to our TBAs and is conditioned upon fact-based representations and covenants made by our management regarding our TBAs. No assurance can be given that the IRS would not assert that such assets are not qualifying assets. If the IRS were to successfully challenge the opinion of Skadden, Arps, Slate, Meagher & Flom LLP, we could be subject to a penalty tax or we could fail to qualify as a REIT if a sufficient portion of our assets consists of TBAs.

No independent appraisals have been obtained to support our conclusions as to the value of our total assets or the value of any particular security or securities. Moreover, values of some assets, including instruments issued in securitization transactions, may not be susceptible to a precise determination, and values are subject to change in the future. Furthermore, the proper classification of an instrument as debt or equity for federal income tax purposes may be uncertain in some circumstances, which could affect the application of the REIT asset requirements. Accordingly, there can be no assurance that the IRS will not contend that our interests in our subsidiaries or in the securities of other issuers will not cause a violation of the REIT asset tests.

qualification if (1) the REIT provides the IRS with a description of each asset causing the failure, (2) the failure is due to reasonable cause and not willful neglect, (3) the REIT pays a tax equal to the greater of (a) $50,000 per failure, and (b) the product of the net income generated by the assets that caused the failure multiplied by the highest applicable corporate tax rate (currently 35%), and (4) the REIT either disposes of the assets causing the failure within six months after the last day of the quarter in which it identifies the failure, or otherwise satisfies the relevant asset tests within that time frame.

In the case of de minimis violations of the 10% and 5% asset tests, a REIT may maintain its qualification despite a violation of such requirements if (1) the value of the assets causing the violation does not exceed the lesser of 1% of the REIT’s total assets and $10,000,000, and (2) the REIT either disposes of the assets causing the failure within six months after the last day of the quarter in which it identifies the failure, or the relevant tests are otherwise satisfied within that time frame.

If we should fail to satisfy the asset tests at the end of a calendar quarter, including any failure to satisfy the 75% asset test as a result of any investments in TBAs, such a failure would not cause us to lose our REIT qualification if we (1) satisfied the asset tests at the close of the preceding calendar quarter and (2) the discrepancy between the value of our assets and the asset requirements was not wholly or partly caused by an acquisition of non-qualifying assets, but instead arose from changes in the market value of our assets. If the condition described in (2) were not satisfied, we still could avoid disqualification by eliminating any discrepancy within 30 days after the close of the calendar quarter in which it arose or by making use of relief provisions described below.

In order to qualify as a REIT, we are required to distribute dividends, other than capital gain dividends, to our stockholders in an amount at least equal to:

(1) 90% of our “REIT taxable income,” computed without regard to our net capital gains and the deduction for dividends paid, and

(2) 90% of our net income, if any, (after tax) from foreclosure property (as described below), minus

We generally must make these distributions in the taxable year to which they relate, or in the following taxable year if declared before we timely file our tax return for the year and if paid with or before the first regular dividend payment after such declaration. In order for distributions to be counted as satisfying the annual distribution requirements for REITs, and to provide us with a tax deduction for us, the distributions must not be “preferential dividends.” A dividend is not a preferential dividend if the distribution is (1) pro rata among all outstanding shares of stock within a particular class, and (2) in accordance with the preferences among different classes of stock as set forth in our organizational documents.

To the extent that we distribute at least 90%, but less than 100%, of our “REIT taxable income,” as adjusted, we will be subject to tax at ordinary corporate tax rates on the retained portion. We may elect to retain, rather than distribute, our net long-term capital gains and pay tax on such gains. In this case, we could elect for our stockholders to include their proportionate shares of such undistributed long-term capital gains in income, and to receive a corresponding credit for their share of the tax that we paid. Our stockholders would then increase their adjusted basis of their stock by the difference between (a) the amounts of capital gain dividends that we designated and that they include in their taxable income, minus (b) the tax that we paid on their behalf with respect to that income.

To the extent that in the future we may have available net operating losses carried forward from prior tax years, such losses may reduce the amount of distributions that we must make in order to comply with the REIT distribution requirements. Such losses, however, will generally not affect the character, in the hands of our stockholders, of any distributions that are actually made as ordinary dividends or capital gains. See “—Taxation of Stockholders—Taxation of Taxable Domestic Stockholders—Distributions.”

If we should fail to distribute during each calendar year at least the sum of (a) 85% of our REIT ordinary income for such year, (b) 95% of our REIT capital gain net income for such year, and (c) any undistributed taxable income from prior periods, we would be subject to a non-deductible 4% excise tax on the excess of such required distribution over the sum of (x) the amounts actually distributed, plus (y) the amounts of income we retained and on which we have paid corporate income tax.

It is possible that, from time to time, we may not have sufficient cash to meet the distribution requirements due to timing differences between (a) our actual receipt of cash, including receipt of distributions from any subsidiaries, and (b) our inclusion of items in income for federal income tax purposes. Other potential sources of non-cash taxable income include:

In the event that such timing differences occur, in order to meet the distribution requirements, it might be necessary for us to arrange for short-term, or possibly long-term, borrowings, or to pay dividends in the form of taxable in-kind distributions of property.

We may be able to rectify a failure to meet the distribution requirements for a year by paying “deficiency dividends” to stockholders in a later year, which may be included in our deduction for dividends paid for the earlier year. In this case, we may be able to avoid losing REIT qualification or being taxed on amounts distributed as deficiency dividends. We will be required to pay interest and a penalty based on the amount of any deduction taken for deficiency dividends.

Net income that we derive from a prohibited transaction is subject to a 100% tax. The term “prohibited transaction” generally includes a sale or other disposition of property (other than foreclosure property, as discussed below) that is held primarily for sale to customers in the ordinary course of a trade or business by us or by a borrower that has issued a shared appreciation mortgage or similar debt instrument to us. We intend to conduct our operations so that no asset that we own (or are treated as owning) will be treated as, or as having been, held for sale to customers, and that a sale of any such asset will not be treated as having been in the ordinary course of our business. Whether property is held “primarily for sale to customers in the ordinary course of a trade or business” depends on the particular facts and circumstances. No assurance can be given that any property that we sell will not be treated as property held for sale to customers, or that we can comply with certain safe-harbor provisions of the Internal Revenue Code that would prevent such treatment. The 100% tax does not apply to gains from the sale of property that is held through a TRS or other taxable corporation, although such income will be subject to tax in the hands of the corporation at regular corporate rates. We intend to continue to structure our activities to avoid prohibited transaction characterization.

ownership or possession by agreement or process of law, after a default (or upon imminent default) on a lease of the property or a mortgage loan held by us and secured by the property, (2) for which we acquired the related loan or lease at a time when default was not imminent or anticipated, and (3) with respect to which we made a proper election to treat the property as foreclosure property. We generally will be subject to tax at the maximum corporate rate (currently 35%) on any net income from foreclosure property, including any gain from the disposition of the foreclosure property, other than income that would otherwise be qualifying income for purposes of the 75% gross income test. Any gain from the sale of property for which a foreclosure property election has been made will not be subject to the 100% tax on gains from prohibited transactions described above, even if the property would otherwise constitute inventory or dealer property. Because we will invest exclusively in agency securities, we do not anticipate receiving any income from foreclosure property that does not qualify for purposes of the 75% gross income test.

We and our subsidiaries may enter into hedging transactions with respect to interest rate exposure on one or more of our assets or liabilities. Any such hedging transactions could take a variety of forms, including the use of derivative instruments such as interest rate swap contracts, interest rate cap or floor contracts, futures or forward contracts, and options. Except to the extent provided by Treasury regulations, any income from a hedging transaction we enter into (1) in the normal course of our business primarily to manage risk of interest rate or price changes or currency fluctuations with respect to borrowings made or to be made, or ordinary obligations incurred or to be incurred, to acquire or carry real estate assets, which is clearly identified as specified in Treasury regulations before the close of the day on which it was acquired, originated, or entered into, including gain from the sale or disposition of such a transaction, and (2) primarily to manage risk of currency fluctuations with respect to any item of income or gain that would be qualifying income under the 75% or 95% income tests which is clearly identified as such before the close of the day on which it was acquired, originated, or entered into, will not constitute gross income for purposes of the 75% or 95% gross income test. To the extent that we enter into other types of hedging transactions, the income from those transactions is likely to be treated as non-qualifying income for purposes of both of the 75% and 95% gross income tests. We intend to structure any hedging transactions in a manner that does not jeopardize our qualification as a REIT. We may conduct some or all of our hedging activities (including hedging activities relating to currency risk) through our TRS or other corporate entity, the income from which may be subject to federal income tax, rather than by participating in the arrangements directly or through pass-through subsidiaries. No assurance can be given, however, that our hedging activities will not give rise to income that does not qualify for purposes of either or both of the REIT gross income tests, or that our hedging activities will not adversely affect our ability to satisfy the REIT qualification requirements.

If we fail to satisfy one or more requirements for REIT qualification other than the income or asset tests, we could avoid disqualification if our failure is due to reasonable cause and not to willful neglect and we pay a penalty of $50,000 for each such failure. Relief provisions are available for failures of the income tests and asset tests, as described above in “—Income Tests” and “—Asset Tests.”

If we fail to qualify for taxation as a REIT in any taxable year, and the relief provisions described above do not apply, we would be subject to tax, including any applicable alternative minimum tax, on our taxable income at regular corporate rates. We cannot deduct distributions to stockholders in any year in which we are not a REIT, nor would we be required to make distributions in such a year. In this situation, to the extent of current and accumulated earnings and profits, distributions to most domestic stockholders that are individuals, trusts and estates will generally be taxable at capital gains rates (through 2012). In addition, subject to the limitations of the Internal Revenue Code, corporate distributees may be eligible for the dividends received deduction. Unless we are entitled to relief under specific statutory provisions, we would also be disqualified from re-electing to be taxed as a REIT for the four taxable years following the year during which we lost qualification. It is not possible to state whether, in all circumstances, we would be entitled to this statutory relief.

Distributions. So long as we qualify as a REIT, the distributions that we make to our taxable domestic stockholders out of current or accumulated earnings and profits that we do not designate as capital gain dividends will generally be taken into account by stockholders as ordinary income and will not be eligible for the dividends received deduction for corporations. With limited exceptions, our dividends are not eligible for taxation at the preferential income tax rates (i.e., the 15% maximum federal rate through 2012) for qualified dividends received by most domestic stockholders that are individuals, trusts and estates from taxable C corporations. Such stockholders, however, are taxed at the preferential rates on dividends designated by and received from REITs to the extent that the dividends are attributable to:

Distributions that we designate as capital gain dividends will generally be taxed to our stockholders as long-term capital gains, to the extent that such distributions do not exceed our actual net capital gain for the taxable year, without regard to the period for which the stockholder that receives such distribution has held its stock. We may elect to retain and pay taxes on some or all of our net long-term capital gains, in which case provisions of the Internal Revenue Code will treat our stockholders as having received, solely for tax purposes, our undistributed capital gains, and the stockholders will receive a corresponding credit for taxes that we paid on such undistributed capital gains. See “Taxation of American Capital Agency Corp.—Annual Distribution Requirements.” Corporate stockholders may be required to treat up to 20% of some capital gain dividends as ordinary income. Long-term capital gains are generally taxable at maximum federal rates of 15% (through 2012) in the case of stockholders that are individuals, trusts and estates, and 35% in the case of stockholders that are corporations. Capital gains attributable to the sale of depreciable real property held for more than 12 months are subject to a 25% maximum federal income tax rate for taxpayers who are taxed as individuals, to the extent of previously claimed depreciation deductions.

Distributions in excess of our current and accumulated earnings and profits will generally represent a return of capital and will not be taxable to a stockholder to the extent that the amount of such distributions does not exceed the adjusted basis of the stockholder’s shares in respect of which the distributions were made. Rather, the distribution will reduce the adjusted basis of the stockholder’s shares. To the extent that such distributions exceed the adjusted basis of a stockholder’s shares, the stockholder generally must include such distributions in income as long-term capital gain, or short-term capital gain if the shares have been held for one year or less. In addition, any dividend that we declare in October, November or December of any year and that is payable to a stockholder of record on a specified date in any such month will be treated as both paid by us and received by the stockholder on December 31 of such year, provided that we actually pay the dividend before the end of January of the following calendar year.

To the extent that we have available net operating losses and capital losses carried forward from prior tax years, such losses may reduce the amount of distributions that we must make in order to comply with the REIT distribution requirements. See “Taxation of American Capital Agency Corp.—Annual Distribution Requirements.” Such losses, however, are not passed through to stockholders and do not offset income of stockholders from other sources, nor would such losses affect the character of any distributions that we make, which are generally subject to tax in the hands of stockholders to the extent that we have current or accumulated earnings and profits.

Dispositions of American Capital Agency Corp. Stock. In general, capital gains recognized by individuals, trusts and estates upon the sale or disposition of our stock will be subject to a maximum federal income tax rate of 15% (through 2012) if the stock is held for more than one year, and will be taxed at ordinary income rates (of up to 35% through 2012) if the stock is held for one year or less. Gains recognized by stockholders that are corporations are subject to federal income tax at a maximum rate of 35%, whether or not such gains are classified as long-term capital gains. Capital losses recognized by a stockholder upon the disposition of our stock that was held for more than one year at the time of disposition will be considered long-term capital losses, and are generally available only to offset capital gain income of the stockholder but not ordinary income (except in the case of individuals, who may offset up to $3,000 of ordinary income each year). In addition, any loss upon a sale or exchange of shares of our stock by a stockholder who has held the shares for six months or less, after applying holding period rules, will be treated as a long-term capital loss to the extent of distributions that we make that are required to be treated by the stockholder as long-term capital gain.

If an investor recognizes a loss upon a subsequent disposition of our stock or other securities in an amount that exceeds a prescribed threshold, it is possible that the provisions of Treasury regulations involving “reportable transactions” could apply, with a resulting requirement to separately disclose the loss-generating transaction to the IRS. These regulations, though directed towards “tax shelters,” are broadly written and apply to transactions that would not typically be considered tax shelters. The Internal Revenue Code imposes significant penalties for failure to comply with these requirements. You should consult your tax advisor concerning any possible disclosure obligation with respect to the receipt or disposition of our stock or securities or transactions that we might undertake directly or indirectly. Moreover, you should be aware that we and other participants in the transactions in which we are involved (including their advisors) might be subject to disclosure or other requirements pursuant to these regulations.

Passive Activity Losses and Investment Interest Limitations. Distributions that we make and gain arising from the sale or exchange by a domestic stockholder of our stock will not be treated as passive activity income. As a result, stockholders will not be able to apply any “passive losses” against income or gain relating to our stock. To the extent that distributions we make do not constitute a return of capital, they will be treated as investment income for purposes of computing the investment interest limitation.

Medicare Tax. For taxable years beginning after December 31, 2012, certain U.S. holders who are individuals, estates or trusts and whose income exceeds certain thresholds will be required to pay a 3.8% Medicare tax on dividend and other income, including capital gains from the sale or other disposition of our common stock.

The following is a summary of certain U.S. federal income and estate tax consequences of the ownership and disposition of our stock applicable to non-U.S. holders. A “non-U.S. holder” is any person other than:

If a partnership, including for this purpose any entity that is treated as a partnership for U.S. federal income tax purposes, holds our common stock, the tax treatment of a partner in the partnership will generally depend upon the status of the partner and the activities of the partnership. An investor that is a partnership and the partners in such partnership should consult their tax advisors about the U.S. federal income tax consequences of the acquisition, ownership and disposition of our common stock.

The following discussion is based on current law, and is for general information only. It addresses only selected, and not all, aspects of U.S. federal income and estate taxation.

Ordinary Dividends. The portion of dividends received by non-U.S. holders that is (1) payable out of our earnings and profits, (2) which is not attributable to our capital gains and (3) which is not effectively connected with a U.S. trade or business of the non-U.S. holder, will be subject to U.S. withholding tax at the rate of 30%, unless reduced or eliminated by treaty.

In general, non-U.S. holders will not be considered to be engaged in a U.S. trade or business solely as a result of their ownership of our stock. In cases where the dividend income from a non-U.S. holder’s investment in our stock is, or is treated as, effectively connected with the non-U.S. holder’s conduct of a U.S. trade or business, the non-U.S. holder generally will be subject to U.S. federal income tax at graduated rates, in the same manner as domestic stockholders are taxed with respect to such dividends. Such income must generally be reported on a U.S. income tax return filed by or on behalf of the non-U.S. holder. The income may also be subject to the 30% branch profits tax in the case of a non-U.S. holder that is a corporation.

Non-Dividend Distributions. Unless our stock constitutes a U.S. real property interest (a “USRPI”), distributions that we make which are not dividends out of our earnings and profits will not be subject to U.S. income tax. If we cannot determine at the time a distribution is made whether or not the distribution will exceed current and accumulated earnings and profits, the distribution will be subject to withholding at the rate applicable to dividends. The non-U.S. holder may seek a refund from the IRS of any amounts withheld if it is subsequently determined that the distribution was, in fact, in excess of our current and accumulated earnings and profits. If our stock constitutes a USRPI, as described below, distributions that we make in excess of the sum of (a) the stockholder’s proportionate share of our earnings and profits, plus (b) the stockholder’s basis in its stock, will be taxed under the Foreign Investment in Real Property Tax Act of 1980 (“FIRPTA”), at the rate of tax, including any applicable capital gains rates, that would apply to a domestic stockholder of the same type (e.g., an individual or a corporation, as the case may be), and the collection of the tax will be enforced by a refundable withholding at a rate of 10% of the amount by which the distribution exceeds the stockholder’s share of our earnings and profits.

Capital Gain Dividends. Under FIRPTA, a distribution that we make to a non-U.S. holder, to the extent attributable to gains from dispositions of USRPIs that we held directly or through pass-through subsidiaries, or USRPI capital gains, will, except as described below, be considered effectively connected with a U.S. trade or business of the non-U.S. holder and will be subject to U.S. income tax at the rates applicable to U.S. individuals or corporations, without regard to whether we designate the distribution as a capital gain dividend. See above under “—Taxation of Foreign Stockholders—Ordinary Dividends,” for a discussion of the consequences of income that is effectively connected with a U.S. trade or business. In addition, we will be required to withhold tax equal to 35% of the maximum amount that could have been designated as USRPI capital gains dividends. Distributions subject to FIRPTA may also be subject to a 30% branch profits tax in the hands of a non-U.S. holder that is a corporation. A distribution is not a USRPI capital gain if we held an interest in the underlying asset solely as a creditor. Capital gain dividends received by a non-U.S. holder that are attributable to dispositions of our assets other than USRPIs are not subject to U.S. federal income or withholding tax, unless (1) the gain is effectively connected with the non-U.S. holder’s U.S. trade or business, in which case the non-U.S. holder would be subject to the same treatment as U.S. holders with respect to such gain, or (2) the non-U.S. holder is a nonresident alien individual who was present in the United States for 183 days or more during the taxable year and has a “tax home” in the United States, in which case the non-U.S. holder will incur a 30% tax on his capital gains.

A capital gain dividend that would otherwise have been treated as a USRPI capital gain will not be so treated or be subject to FIRPTA, and generally will not be treated as income that is effectively connected with a U.S. trade or business, and instead will be treated in the same manner as an ordinary dividend (see “—Taxation of Foreign Stockholders—Ordinary Dividends”), if (1) the capital gain dividend is received with respect to a class of stock that is regularly traded on an established securities market located in the United States, and (2) the recipient non-U.S. holder does not own more than 5% of that class of stock at any time during the year ending on the date on which the capital gain dividend is received. We anticipate that our common stock will continue to be “regularly traded” on an established securities exchange.

Dispositions of American Capital Agency Corp. Stock. Unless our stock constitutes a USRPI, a sale of our stock by a non-U.S. holder generally will not be subject to U.S. taxation under FIRPTA. Our stock will not be treated as a USRPI if less than 50% of our assets throughout a prescribed testing period consist of interests in real property located within the United States, excluding, for this purpose, interests in real property solely in a capacity as a creditor. It is not currently anticipated that our stock will constitute a USRPI. However, we cannot assure you that our stock will not become a USRPI.

Even if the foregoing 50% test is not met, our stock nonetheless will not constitute a USRPI if we are a “domestically controlled qualified investment entity.” A domestically controlled qualified investment entity includes a REIT, less than 50% of value of which is held directly or indirectly by non-U.S. holders at all times during a specified testing period. We believe that we are, and we will be, a domestically controlled qualified investment entity, and that a sale of our stock should not be subject to taxation under FIRPTA. However, no assurance can be given that we are or will remain a domestically controlled qualified investment entity.

In the event that we are not a domestically controlled qualified investment entity, but our stock is “regularly traded,” as defined by applicable Treasury regulations, on an established securities market, a non-U.S. holder’s sale of our common stock nonetheless would not be subject to tax under FIRPTA as a sale of a USRPI, provided that the selling non-U.S. holder held 5% or less of our outstanding common stock any time during the one-year period ending on the date of the sale. We expect that our common stock will continue to be regularly traded on an established securities market.

If gain on the sale of our stock were subject to taxation under FIRPTA, the non-U.S. holder would be required to file a U.S. federal income tax return and would be subject to the same treatment as a domestic stockholder with respect to such gain, subject to applicable alternative minimum tax and a special alternative minimum tax in the case of non-resident alien individuals, and the purchaser of the stock could be required to withhold 10% of the purchase price and remit such amount to the IRS.

Gain from the sale of our stock that would not otherwise be subject to FIRPTA will nonetheless be taxable in the United States to a non-U.S. holder in two cases: (1) if the non-U.S. holder’s investment in our stock is effectively connected with a U.S. trade or business conducted by such non-U.S. holder, the non-U.S. holder will be subject to the same treatment as a domestic stockholder with respect to such gain, or (2) if the non-U.S. holder is a nonresident alien individual who was present in the United States for 183 days or more during the taxable year and has a “tax home” in the United States, the nonresident alien individual will be subject to a 30% tax on the individual’s capital gain. In addition, even if we are a domestically controlled qualified investment entity, upon disposition of our stock (subject to the 5% exception applicable to “regularly traded” stock described above), a non-U.S. holder may be treated as having gain from the sale or exchange of a USRPI if the non-U.S. holder (1) disposes of our common stock within a 30-day period preceding the ex-dividend date of a distribution, any portion of which, but for the disposition, would have been treated as gain from the sale or exchange of a USRPI and (2) acquires, or enters into a contract or option to acquire, other shares of our common stock within 30 days after such ex-dividend date.

Other Withholding Rules. After December 31, 2013, withholding at a rate of 30% will be required on dividends in respect of, and after December 31, 2014, withholding at a rate of 30% will be required on gross

proceeds from the sale of, shares of our stock held by or through certain foreign financial institutions (including investment funds), unless such institution enters into an agreement with the Secretary of the Treasury to report, on an annual basis, information with respect to shares in, and accounts maintained by, the institution to the extent such shares or accounts are held by certain U.S. persons or by certain non-U.S. entities that are wholly or partially owned by U.S. persons. Accordingly, the entity through which our shares are held will affect the determination of whether such withholding is required. Similarly, after December 31, 2013, dividends in respect of, and after December 31, 2014, gross proceeds from the sale of, our shares held by an investor that is a non-financial non-U.S. entity will be subject to withholding at a rate of 30%, unless such entity either (i) certifies to us that such entity does not have any “substantial U.S. owners” or (ii) provides certain information regarding the entity’s “substantial U.S. owners,” which we will in turn provide to the Secretary of the Treasury. Non-U.S. holders are encouraged to consult with their tax advisers regarding the possible implications of these rules on their investment in our common stock.

Estate Tax. If our stock is owned or treated as owned by an individual who is not a citizen or resident (as specially defined for U.S. federal estate tax purposes) of the United States at the time of such individual’s death, the stock will be includable in the individual’s gross estate for U.S. federal estate tax purposes, unless an applicable estate tax treaty provides otherwise, and may therefore be subject to U.S. federal estate tax.

Tax-exempt entities, including qualified employee pension and profit sharing trusts and individual retirement accounts, generally are exempt from federal income taxation. However, they may be subject to taxation on their unrelated business taxable income (“UBTI”). While some investments in real estate may generate UBTI, the IRS has ruled that dividend distributions from a REIT to a tax-exempt entity do not constitute UBTI. Based on that ruling, and provided that (1) a tax-exempt stockholder has not held our stock as “debt financed property” within the meaning of the Internal Revenue Code (i.e., where the acquisition or holding of the property is financed through a borrowing by the tax-exempt stockholder), and (2) our stock is not otherwise used in an unrelated trade or business, distributions that we make and income from the sale of our stock generally should not give rise to UBTI to a tax-exempt stockholder.

Tax-exempt stockholders that are social clubs, voluntary employee benefit associations, supplemental unemployment benefit trusts, and qualified group legal services plans exempt from federal income taxation under sections 501(c)(7), (c)(9), (c)(17) and (c)(20) of the Internal Revenue Code are subject to different UBTI rules, which generally require such stockholders to characterize distributions that we make as UBTI.

In certain circumstances, a pension trust that owns more than 10% of our stock could be required to treat a percentage of the dividends as UBTI if we are a “pension-held REIT.” We will not be a pension-held REIT unless (1) we are required to “look through” one or more of our pension trust stockholders in order to satisfy the REIT “closely-held” test, and (2) either (i) one pension trust owns more than 25% of the value of our stock, or (ii) one or more pension trusts, each individually holding more than 10% of the value of our stock, collectively owns more than 50% of the value of our stock. Certain restrictions on ownership and transfer of our stock generally should prevent a tax-exempt entity from owning more than 10% of the value of our stock and generally should prevent us from becoming a pension-held REIT.

Tax-exempt stockholders are urged to consult their tax advisors regarding the federal, state, local and foreign income and other tax consequences of owning American Capital Agency Corp. stock.

involved in the legislative process and by the IRS and the U.S. Treasury Department which may result in statutory changes as well as revisions to regulations and interpretations. Changes to the federal tax laws and interpretations thereof could adversely affect an investment in our common stock.

We and our subsidiaries and stockholders may be subject to state, local or foreign taxation in various jurisdictions including those in which we or they transact business, own property or reside. We may own properties located in numerous jurisdictions, and may be required to file tax returns in some or all of those jurisdictions. Our state, local or foreign tax treatment and that of our stockholders may not conform to the federal income tax treatment discussed above. We may pay foreign property taxes, and dispositions of foreign property or operations involving, or investments in, foreign property may give rise to foreign income or other tax liability in amounts that could be substantial. Any foreign taxes that we incur do not pass through to stockholders as a credit against their U.S. federal income tax liability. Prospective investors should consult their tax advisors regarding the application and effect of state, local and foreign income and other tax laws on an investment in our stock.

Merrill Lynch, Pierce Fenner & Smith Incorporated, Citigroup Global Markets Inc., Goldman, Sachs & Co., J.P. Morgan Securities LLC and UBS Securities LLC are acting as the joint book-running managers and representatives of the underwriters named below. Subject to the terms and conditions stated in the underwriting agreement dated the date of this prospectus supplement, each underwriter named below has severally agreed to purchase, and we have agreed to sell to that underwriter, the number of shares set forth opposite the underwriter’s name.

The underwriting agreement provides that the obligations of the underwriters to purchase the shares included in this offering are subject to approval of legal matters by counsel and to other conditions. The underwriters are obligated to purchase all the shares (other than those covered by the over-allotment option described below) if they purchase any of the shares.

The underwriters have agreed to purchase the shares of common stock from us at a price of $29.00 per share, which will result in net proceeds to us, after deducting estimated expenses related to this offering, of approximately $1.80 billion assuming no exercise of the over-allotment option granted to the underwriters, and $2.06 billion assuming full exercise of the over-allotment option.

The underwriters propose to offer the common shares offered hereby from time to time for sale in one or more transactions on The Nasdaq Global Select Market, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices, subject to receipt of acceptance by them and subject to their right to reject any order in whole or in part. The underwriters may effect such transactions by selling the common shares to or through dealers and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or purchasers of common shares for whom they may act as agents or to whom they may sell as principal. The difference between the price at which the underwriters purchase shares and the price at which the underwriters resells such shares, which may include a commission equivalent of up to $0.05 per share, may be deemed underwriting compensation. Additionally, we have agreed to reimburse the underwriters for their expenses in an amount of up to $10,000, which may be incurred in connection with the review by Financial Industry Regulatory Authority, Inc. of the terms of the shares offered hereby.

If the underwriters sell more shares than the total number set forth in the table above, we have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase up to 9,150,000 additional shares at $29.00 per share. The underwriters may exercise the option solely for the purpose of covering overallotments, if any, in connection with this offering. To the extent the option is exercised, each underwriter must purchase a number of additional shares approximately proportionate to that underwriter’s initial purchase commitment. Any shares issued or sold under the option will be issued and sold on the same terms and conditions as the other shares that are the subject of this offering.

We, our Manager and each of our executive officers and directors, have agreed that, for a period of 30 days from the date of this prospectus supplement, we and they will not, without the prior written consent of each of the representatives, dispose of or hedge any shares or any securities convertible into or exchangeable for our common stock, subject to certain exceptions, including our ability to continue to sell securities under our dividend reinvestment and direct stock purchase program (without granting waivers as to requests to purchase shares of our common stock in excess of $10,000). The representatives, in their sole discretion, may release any of the securities subject to these lock-up agreements at any time without notice.

We estimate that our portion of the total expenses of this offering will be $500,000.

In connection with the offering, the underwriters may purchase and sell shares in the open market. Purchases and sales in the open market may include short sales, purchases to cover short positions, which may include purchases pursuant to the over-allotment option, and stabilizing purchases.

Purchases to cover short positions and stabilizing purchases, as well as other purchases by the underwriters for their own accounts, may have the effect of preventing or retarding a decline in the market price of the shares. They may also cause the price of the shares to be higher than the price that would otherwise exist in the open market in the absence of these transactions. The underwriters may conduct these transactions on The Nasdaq Global Select Market, in the over-the-counter market or otherwise. If the underwriters commence any of these transactions, they may discontinue them at any time.

A prospectus in electronic format is being made available on Internet websites maintained by one or more of the underwriters of this offering and may be made available on websites maintained by other underwriters. Other than the prospectus in electronic format, the information on any underwriter’s website and any information contained in any other website maintained by an underwriter is not part of the prospectus supplement or the registration statement of which the prospectus supplement forms a part.

In the ordinary course of business, the underwriters or their affiliates have engaged and may in the future engage in various financing, commercial banking and investment banking services with, and provide financial advisory services to, us and our affiliates, for which they have received or may receive customary fees and expenses, including acting as underwriters for our equity offerings. We have entered into master repurchase agreements with an affiliate of Merrill Lynch, Pierce Fenner & Smith Incorporated, Citigroup Global Markets Inc., Goldman, Sachs & Co., J.P. Morgan Securities LLC, UBS Securities LLC, Barclays Capital Inc. and Nomura Securities International, Inc. We have also entered into ISDA master agreements with affiliates of Merrill Lynch, Pierce Fenner & Smith Incorporated, Citigroup Global Markets Inc., Goldman, Sachs & Co., J.P. Morgan Securities LLC, UBS Securities LLC, Barclays Capital Inc. and Nomura Securities International, Inc. Furthermore, we have entered into master securities forward transaction agreements with J.P. Morgan Securities LLC, UBS Securities LLC, Barclays Capital Inc. and Nomura Securities International, Inc. Additionally, affiliates of Citigroup Global Markets Inc. and Goldman, Sachs & Co. are counterparties to ISDA master agreements, Citigroup Global Markets Inc. is a counterparty to a master securities forward transaction agreement and Citigroup Global Markets Inc. and Goldman, Sachs & Co. are counterparties to master repurchase agreements, such agreements entered into by our taxable REIT Subsidiary, American Capital Agency TRS, LLC, and such agreements include a guaranty by American Capital Agency Corp.

Citigroup Global Markets Inc. and UBS Securities LLC have also acted as underwriters and/or financial advisors on a number of equity and/or debt offerings by American Capital. Affiliates of Citigroup Global Markets Inc. are currently lenders under American Capital’s unsecured revolving line of credit.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the underwriters may be required to make because of any of those liabilities.

In relation to each member state of the European Economic Area that has implemented the Prospectus Directive (each, a relevant member state), with effect from and including the date on which the Prospectus Directive is implemented in that relevant member state (the relevant implementation date), an offer of shares described in this prospectus supplement may not be made to the public in that relevant member state prior to the publication of a prospectus in relation to the shares that has been approved by the competent authority in that relevant member state or, where appropriate, approved in another relevant member state and notified to the competent authority in that relevant member state, all in accordance with the Prospectus Directive, except that, with effect from and including the relevant implementation date, an offer of securities may be offered to the public in that relevant member state at any time:

Each purchaser of shares described in this prospectus supplement located within a relevant member state will be deemed to have represented, acknowledged and agreed that it is a “qualified investor” within the meaning of Article 2(1)(e) of the Prospectus Directive.

For purposes of this provision, the expression an “offer to the public” in any relevant member state means the communication in any form and by any means of sufficient information on the terms of the offer and the securities to be offered so as to enable an investor to decide to purchase or subscribe the securities, as the expression may be varied in that member state by any measure implementing the Prospectus Directive in that member state, and the expression “Prospectus Directive” means Directive 2003/71/EC and includes any relevant implementing measure in each relevant member state.

The sellers of the shares have not authorized and do not authorize the making of any offer of shares through any financial intermediary on their behalf, other than offers made by the underwriters with a view to the final placement of the shares as contemplated in this prospectus supplement. Accordingly, no purchaser of the shares, other than the underwriters, is authorized to make any further offer of the shares on behalf of the sellers or the underwriters.

This prospectus supplement and the accompanying prospectus are only being distributed to, and are only directed at, persons in the United Kingdom that are qualified investors within the meaning of Article 2(1)(e) of the Prospectus Directive that are also (i) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (the “Order”) or (ii) high net worth entities, and other persons to whom it may lawfully be communicated, falling within Article 49(2)(a) to (d) of the Order (each such person being referred to as a “relevant person”). This prospectus supplement and its contents are confidential and should not be distributed, published or reproduced (in whole or in part) or disclosed by recipients to any other persons in the United Kingdom. Any person in the United Kingdom that is not a relevant person should not act or rely on this document or any of its contents.

Neither this prospectus supplement nor any other offering material relating to the shares described in this prospectus supplement has been submitted to the clearance procedures of the Autorité des Marchés Financiers or of the competent authority of another member state of the European Economic Area and notified to the Autorité des Marchés Financiers. The shares have not been offered or sold and will not be offered or sold, directly or indirectly, to the public in France.

Neither this prospectus supplement nor any other offering material relating to the shares has been or will be:

The shares may be resold directly or indirectly, only in compliance with articles L.411-1, L.411-2, L.412-1 and L.621-8 through L.621-8-3 of the French Code monétaire et financier.

This prospectus does not constitute an issue prospectus pursuant to Article 652a or Article 1156 of the Swiss Code of Obligations (“CO”) and the shares will not be listed on the SIX Swiss Exchange. Therefore, the prospectus may not comply with the disclosure standards of the CO and/or the listing rules (including any prospectus schemes) of the SIX Swiss Exchange. Accordingly, the shares may not be offered to the public in or from Switzerland, but only to a selected and limited circle of investors, which do not subscribe to the shares with a view to distribution.

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The securities to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the securities offered should conduct their own due diligence on the securities. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

The shares may be resold directly or indirectly, only in compliance with articles L.411-1, L.411-2, L.412-1 and L.621-8 through L.621-8-3 of the French Code monétaire et financier.

Certain legal matters in connection with this offering will be passed upon for us by Skadden, Arps, Slate, Meagher & Flom LLP, New York, New York. Certain legal matters in connection with this offering will be passed upon for the underwriters by Hunton & Williams LLP.

The consolidated financial statements of American Capital Agency Corp. appearing in American Capital Agency Corp.’s Annual Report (Form 10-K) for the year ended December 31, 2011, and the effectiveness of American Capital Agency Corp.’s internal control over financial reporting as of December 31, 2011 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any reports or other information that we file with the SEC at the SEC’s Public Reference Room located at 100 F Street, N.E., Washington D.C. 20549. You may also receive copies of these documents upon payment of a duplicating fee, by writing to the SEC’s Public Reference Room. Please call the SEC at 1-800-SEC-0330 for further information on the Public Reference Room in Washington D.C. Our SEC filings are also available to you, free of charge, on the SEC’s website at http://www.sec.gov. You may also obtain additional information by visiting our website at http://www.AGNC.com. The information found on, or otherwise accessible through, our website is not incorporated into, and does not form a part of this prospectus supplement or any other report or document we file with or furnish to the SEC.

The SEC allows us to “incorporate by reference” information into this prospectus supplement which has been previously filed, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus supplement, except for any information superseded by information included or incorporated by reference in this prospectus supplement. We have filed the documents listed below with the SEC (File No. 001-34057) under the Exchange Act and these documents are incorporated herein by reference:

All documents that we file (but not those that we furnish) with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of the initial registration statement of which this prospectus supplement is a part and prior to effectiveness of the registration statement will be deemed to be incorporated by reference into this prospectus supplement and will automatically update and supersede the information in this prospectus supplement and any previously filed document. In addition, all documents that we file (but not those that we furnish) with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement and prior to the termination of the offering of shares hereby will be deemed to be incorporated by reference into this prospectus supplement and will automatically update and supersede the information in this prospectus supplement and any previously filed document.

We will provide to each person, including any beneficial owner, to whom a copy of this prospectus supplement is delivered, a copy of any or all of the information that has been incorporated by reference in this prospectus supplement but not delivered with this prospectus supplement (other than the exhibits to such documents which are not specifically incorporated by reference herein); we will provide this information at no cost to the requester upon written or oral request to American Capital Agency Corp., 2 Bethesda Metro Center, 14th Floor, Bethesda, Maryland 20814, telephone number (301) 968-9300.

By this prospectus, we may offer, from time to time, shares of our common stock and preferred stock in one or more offerings (the “Securities”). The Securities may be offered separately or together in amounts and at prices and on terms to be disclosed in one or more supplements to this prospectus. We may describe the terms of these offerings in a term sheet that will precede the prospectus supplement. You should read this prospectus and any supplement or term sheet carefully before you decide to invest. This prospectus may not be used to consummate sales of any Securities unless it is accompanied by a prospectus supplement.

Our common stock is listed on The NASDAQ Global Select Market under the symbol “AGNC.” As of November 3, 2010, the last reported sales price for our common stock was $28.90 per share.

Our amended and restated certificate of incorporation contains certain restrictions relating to the ownership and transfer of both our common stock and our capital stock, including a 9.8% ownership limit. These ownership limitations are intended to assist us in qualifying and maintaining our qualifications as a real estate investment trust.

Investing in our Securities involves significant risks. You should carefully consider these risks together with all of the other information contained in this prospectus and any prospectus supplement before making a decision to purchase our Securities. See “Risk Factors” beginning on page 3 of this prospectus.

The Securities may be sold directly by us, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section in this prospectus entitled “Plan of Distribution.” If any underwriters are involved in the sale of any Securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable commissions or discounts will be set forth in the prospectus supplement. The net proceeds that we expect to receive from such sale will also be set forth in the prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

You should rely only on the information contained in this prospectus and any applicable prospectus supplement. We have not authorized anyone to provide you with different or additional information. This prospectus and any applicable prospectus supplement does not constitute an offer to sell, or a solicitation of an offer to purchase, the Securities offered by such documents in any jurisdiction to or from any person to whom or from whom it is unlawful to make such offer or solicitation of an offer in such jurisdiction. You should not assume that the information contained in this prospectus or any prospectus supplement is accurate as of any date other than the date on the front cover of such documents. Neither the delivery of this prospectus or any applicable prospectus supplement nor any distribution of Securities pursuant to such documents shall, under any circumstances, create any implication that there has been no change in the information set forth in this prospectus or any applicable prospectus supplement or in our affairs since the date of this prospectus or any applicable prospectus supplement.

This prospectus contains, and any applicable prospectus supplement may contain, summaries of certain provisions contained in some of the documents described herein and therein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to have been filed or incorporated by reference as exhibits to the registration statement of which this prospectus is a part and you may obtain copies of those documents as described below under “Where You Can Find More Information.”

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, using a “shelf” registration process. Under this shelf registration process, we may sell any combination of the Securities in one or more offerings. This prospectus provides you with a general description of the Securities that we may offer. Each time that we sell Securities under this shelf registration statement, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. This prospectus, together with applicable prospectus supplements, includes all material information relating to this offering. Please carefully read both this prospectus and any prospectus supplement together with the additional information described below under “Where You Can Get More Information.”

The SEC allows us to incorporate by reference information that we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information. You should rely only on the information we have provided or incorporated by reference in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the Securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus or any prospectus supplement is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference. Our business, financial condition, results of operations and prospects may have changed since that date.

We make forward looking statements in this prospectus that are subject to risks and uncertainties. These forward looking statements include information about possible or assumed future results of our business and our financial condition, liquidity, results of operations, plans and objectives. They also include, among other things, statements concerning anticipated revenues, income or loss, capital expenditures, dividends, capital structure, or other financial terms, as well as statements regarding subjects that are forward looking by their nature, such as:

When we use words such as “will likely result,” “plan,” “may,” “shall,” “believe,” “expect,” “anticipate,” “project,” “intend,” “estimate,” “goal,” “objective,” or similar expressions, we intend to identify forward looking statements. You should not place undue reliance on these forward looking statements, which apply only as of the date of this prospectus. We do not intend and disclaim any duty or obligation to update or revise any industry information or forward looking statement set forth in this prospectus to reflect new information, future events, or otherwise, except as required under U.S. federal securities laws.

PROSPECTUS SUMMARY

This summary highlights key aspects of this offering. This summary is not complete and does not contain all of the information that you should consider before investing in our Securities. You should read carefully the other information included and incorporated by reference in this prospectus before investing in our Securities. Except where the context suggests otherwise, in this prospectus, “the Company,” “we,” “us” and “our” refer to American Capital Agency Corp.

Our Company

We earn income primarily from investing in residential mortgage pass-through securities and collateralized mortgage obligations on a leveraged basis. These investments consist of securities for which the principal and interest payments are guaranteed by U.S. Government-sponsored entities such as the Federal National Mortgage Association, or Fannie Mae, and the Federal Home Loan Mortgage Corporation, or Freddie Mac, or by a U.S. Government agency such as the Government National Mortgage Association, or Ginnie Mae. We refer to these securities as agency securities and to the securities we own as our investment portfolio. We have elected to be taxed as a real estate investment trust, or REIT, under the Internal Revenue Code of 1986, as amended. As long as we qualify as a REIT, we generally will not be subject to federal income taxes on our taxable income to the extent we annually distribute all of our taxable income to stockholders.

We are externally managed by American Capital Agency Management, LLC, which we refer to as our Manager. Our Manager is a subsidiary of a wholly owned portfolio company of American Capital, Ltd. (“American Capital”), an investment company and alternative asset manager that is listed on The NASDAQ Global Select Market under the symbol “ACAS.” Because we have no employees, our Manager is responsible for administering our business activities and day to day operations, subject to the supervision of our Board of Directors.

Our principal goal is to generate net income for distribution to our stockholders through regular quarterly dividends from our net interest income, which is the spread between the interest income earned on our investment portfolio and the interest costs of our borrowings and hedging activities. We fund our investments through short-term borrowings structured as repurchase agreements.

Our Corporate Information

We are a Delaware corporation, which was formed on January 7, 2008. We commenced operations on May 20, 2008 upon completion of our initial public offering. Our principal place of business is located at 2 Bethesda Metro Center, 14th Floor, Bethesda, Maryland, 20814, and our telephone number is (301) 968-9300. Our Internet address is www.agnc.com. The information found on, or otherwise accessible through, our website is not incorporated into, and does not form a part of, this prospectus or any other report or document we file with or furnish to the SEC.

THE SECURITIES WE MAY OFFER

This prospectus provides you with a general description of the Securities we may offer. Each time we sell Securities, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

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designation or classification;

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redemption terms;

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dividends;

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listing on a securities exchange;

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conversion rights;

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voting or other rights; and

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a discussion of any other material U.S. federal income tax considerations applicable to the Securities being offered.

The prospectus supplement also may add, update or change information contained in this prospectus or in documents we incorporate by reference. This prospectus may not be used to consummate a sale of Securities unless accompanied by a prospectus supplement.

Our Securities may be offered directly to one or more purchasers, including existing stockholders, by us or through agents designated from time to time by us, or to or through underwriters or dealers. The prospectus supplement relating to the offering will disclose the terms of the offering, including the name or names of any agents or underwriters involved in the sale of our Securities by us, the purchase price, and any fee, commission or discount arrangement between us and our agents or underwriters or among our underwriters or the basis upon which such amount may be calculated. See “Plan of Distribution.” We may not sell any of our Securities through agents, underwriters or dealers without delivery of a prospectus supplement describing the method and terms of the offering of our Securities.

Common Stock

We may issue shares of our common stock from time to time. Subject to the restrictions contained in our amended and restated certificate of incorporation regarding the transfer and ownership of our capital stock and except as may otherwise be specified in the terms of any class or series of common stock, our common stockholders are entitled to one vote per share. Our common stockholders are not entitled to cumulate their votes in the election of directors. Generally, all matters to be voted on by stockholders must be approved by a majority (or, in the case of election of directors, by a plurality) of the votes entitled to be cast by all holders of our common stock present in person or represented by proxy, voting together as a single class. Except as otherwise provided by law, amendments to our amended and restated certificate of incorporation must be approved by a majority or, in some cases, a super-majority of the combined voting power of all shares of common stock, voting together as a single class.

Subject to the restrictions contained in our amended and restated certificate of incorporation regarding the transfer and ownership of our capital stock, our common stockholders will share ratably (based on the number of common shares held) if and when any dividend is declared on our common stock by our Board of Directors. Dividends consisting of common stock may be paid only as follows: (i) common stock may be paid only to holders of common stock; and (ii) shares shall be paid proportionally with respect to each outstanding share of common stock. We may not subdivide or combine shares of any class of common stock or issue a dividend on shares of any class of common stock without at the same time proportionally subdividing or combining shares of any other class or issuing a similar dividend on any other class.

Preferred Stock

We may issue shares of our preferred stock in one or more series and will determine the dividend, voting and conversion rights and other provisions at the time of sale. Our amended and restated certificate of incorporation provides that our Board of Directors has the authority, without action by the stockholders, to designate and issue up to 10,000,000 shares of preferred stock in one or more classes or series and to fix the rights, preferences, privileges and restrictions of each class or series of preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences and the number of shares constituting any class or series, which may be greater than the rights of the holders of the common stock. Any issuance of shares of preferred stock could adversely affect the voting power of holders of common stock, and the likelihood that the holders will receive dividend payments and payments upon liquidation could have the effect of delaying, deferring or preventing a change in control.

Investing in our Securities involves a high degree of risk. You should carefully consider the risks described under “Risk Factors” in our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q (which descriptions are incorporated by reference herein), as well as the other information contained or incorporated by reference in this prospectus or in any prospectus supplement hereto before making a decision to invest in our Securities. See “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference” below.

Unless otherwise specified in a prospectus supplement accompanying this prospectus, we intend to use the net proceeds from our sale of the Securities offered by this prospectus and the related prospectus supplement to finance the acquisition of agency securities and for other general corporate purposes such as repayment of outstanding indebtedness, working capital, and for liquidity needs. Pending this utilization, we may invest the net proceeds from an offering in readily marketable, short-term, interest-bearing investments, including money market accounts that are consistent with our intention to maintain our qualification as a REIT. These temporary investments are expected to provide a lower net return than we hope to achieve from our targeted investments in agency securities.

The following table sets forth our ratios of earnings to combined fixed charges and preferred stock dividends for each of the periods indicated:

For purposes of computing the ratio of earnings to combined fixed charges and preferred stock dividends, earnings represent net income plus fixed charges and preferred stock dividends (where applicable). Fixed charges include interest expense, a portion of rent expense and preferred stock dividend expense. We currently have no shares of preferred stock outstanding and, therefore, there are no amounts for preferred dividends included in the above calculation. We have assumed that one-third of the actual rental expense for the periods presented represents a reasonable approximation of fixed charges.

We may sell the Securities offered pursuant to this prospectus and any accompanying prospectus supplements to or through one or more underwriters or dealers or we may sell the Securities to investors directly or through agents. Each prospectus supplement, to the extent applicable, will describe the number and terms of the Securities to which such prospectus supplement relates, the name or names of any underwriters or agents with whom we have entered into arrangements with respect to the sale of such Securities, the public offering or purchase price of such Securities and the net proceeds we will receive from such sale. Any underwriter or agent involved in the offer and sale of the Securities will be named in the applicable prospectus supplement. We may sell Securities directly to investors on our own behalf in those jurisdictions where we are authorized to do so.

Underwriters may offer and sell the Securities at a fixed price or prices, which may be changed from time to time, at market prices prevailing at the time of sale, at prices related to the prevailing market prices or at negotiated prices. We also may, from time to time, authorize dealers or agents to offer and sell these Securities upon such terms and conditions as may be set forth in the applicable prospectus supplement. In connection with the sale of any of these Securities, underwriters may receive compensation from us in the form of underwriting discounts or commissions and may also receive commissions from purchasers of the Securities for whom they may act as agent. Underwriters may sell the Securities to or through dealers, and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for which they may act as agents.

Securities may also be sold in one or more of the following transactions: (a) block transactions (which may involve crosses) in which a broker-dealer may sell all or a portion of the Securities as agent but may position and resell all or a portion of the block as principal to facilitate the transaction; (b) purchases by a broker-dealer as principal and resale by the broker-dealer for its own account pursuant to a prospectus supplement; (c) a special offering, an exchange distribution or a secondary distribution in accordance with applicable Nasdaq Stock Market or other stock exchange rules; (d) ordinary brokerage transactions and transactions in which a broker-dealer solicits purchasers; (e) sales “at the market” to or through one or more market makers or into an existing trading market, on an exchange or otherwise, for Securities; and (f) sales in other ways not involving market makers or established trading markets, including direct sales to purchasers. Broker-dealers may also receive compensation from purchasers of the Securities which is not expected to exceed that customary in the types of transactions involved.

We will set forth in a prospectus supplement the terms of the offering of Securities, including:

If we use underwriters for a sale of Securities, the underwriters will acquire the Securities for their own account. The underwriters may resell the Securities in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the Securities will be subject to the conditions set forth in the applicable underwriting agreement. The underwriters will be obligated to purchase all the Securities of the series offered if they purchase any of the Securities of that series. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement naming the underwriter the nature of any such relationship.

Underwriters, dealers or agents may receive compensation in the form of discounts, concessions or commissions from us or from our purchasers (as their agents in connection with the sale of Securities). These underwriters, dealers or agents may be considered to be underwriters under the Securities Act of 1933 (the “Securities Act”). As a result, discounts, commissions or profits on resale received by the underwriters, dealers or agents may be treated as underwriting discounts and commissions. The prospectus supplement accompanying this prospectus will identify any such underwriter, dealer or agent, and describe any compensation received by them from us. Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time. Unless otherwise indicated in a prospectus supplement, an agent will be acting on a best efforts basis and a dealer will purchase Securities as a principal, and may then resell the Securities at varying prices to be determined by the dealer.

Underwriters, dealers and agents may be entitled to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments made by the underwriters, dealers or agents, under agreements between us and the underwriters, dealers and agents.

We may grant underwriters who participate in the distribution of Securities an option to purchase additional Securities to cover over-allotments, if any, in connection with the distribution.

To facilitate the offering of Securities, certain persons participating in the offering may engage in transactions that stabilize, maintain, or otherwise affect the price of the Securities. This may include over-allotments or short sales of the Securities, which involve the sale by persons participating in the offering of more Securities than we sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment option, if any. In addition, these persons may stabilize or maintain the price of the Securities by bidding for or purchasing Securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if Securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the Securities at a level above that which might otherwise prevail in the open market. These transactions, if commenced, may be discontinued at any time.

Any person participating in a distribution of the Securities covered by this prospectus will be subject to the applicable provisions of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules and regulations thereunder. Regulation M of the Exchange Act may limit the timing of purchases and sales of Securities by such person. In addition, Regulation M may restrict the ability of any person engaged in the distribution of the Securities to engage in market-making activities with respect to our Securities for a period of up to five business days before the distribution.

In compliance with the guidelines of the Financial Industry Regulatory Authority, Inc. (“FINRA”), the maximum aggregate discounts, commissions, agency fees or other items constituting underwriting compensation to be received by any FINRA member or independent broker-dealer will not exceed 8% of the aggregate offering price of the securities offered pursuant to this prospectus and any applicable prospectus supplement.

The following is a summary of the rights and preferences of our Securities and related provisions of our amended and restated certificate of incorporation and by-laws. While we believe that the following description covers the material terms of our capital stock, the description may not contain all of the information that is important to you. We encourage you to read carefully this entire prospectus, our amended and restated certificate of incorporation and by-laws and the other documents we refer to for a more complete understanding of our capital stock. See “Where You Can Find More Information.”

Our amended and restated certificate of incorporation provides that we may issue up to 150,000,000 shares of common stock and 10,000,000 shares of preferred stock, both having a par value of $0.01 per share. As of November 4, 2010, 52,191,805 shares of our common stock and no shares of our preferred stock were issued and outstanding.

Subject to the restrictions contained in our amended and restated certificate of incorporation regarding the transfer and ownership of our capital stock and except as may otherwise be specified in the terms of any class or series of common stock, our common stockholders are entitled to one vote per share. Our common stockholders are not entitled to cumulate their votes in the election of directors. Generally, all matters to be voted on by stockholders must be approved by a majority (or, in the case of election of directors, by a plurality) of the votes entitled to be cast by all holders of our common stock present in person or represented by proxy, voting together as a single class. Except as otherwise provided by law, amendments to our amended and restated certificate of incorporation must be approved by a majority or, in some cases, a super-majority of the combined voting power of all shares of common stock, voting together as a single class.

Subject to the restrictions contained in our amended and restated certificate of incorporation regarding the transfer and ownership of our capital stock, our common stockholders will share ratably (based on the number of common shares held) if and when any dividend is declared by our Board of Directors. Dividends consisting of common stock may be paid only as follows: (i) common stock may be paid only to holders of common stock; and (ii) shares shall be paid proportionally with respect to each outstanding common share. We may not subdivide or combine shares of any class of common stock or issue a dividend on shares of any class of common stock without at the same time proportionally subdividing or combining shares of any other class or issuing a similar dividend on any other class.

On our liquidation, dissolution or winding up, each of our common stockholders will be entitled to a pro rata dividend of any assets available for dividend to common stockholders.

In the event of our merger or consolidation with or into another company in connection with which shares of common stock are converted into or exchangeable for shares of stock, other securities or property (including cash), our common stockholders, will be entitled to receive the same kind and amount of shares of stock and other securities and property (including cash). No shares of our common stock will be subject to redemption or have preemptive rights to purchase additional shares.

Our amended and restated certificate of incorporation provides that our Board of Directors has the authority, without action by the stockholders, to designate and issue up to 10,000,000 shares of preferred stock in one or more classes or series and to fix the rights, preferences, privileges and restrictions of each class or series of preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences and the number of shares constituting any class or series, which may be greater than the rights of the holders of the common stock. Any issuance of shares of preferred stock could adversely affect the voting power of holders of common stock, and the likelihood that the holders will receive dividend payments and payments upon liquidation could have the effect of delaying, deferring or preventing a change in control.

This prospectus provides you with a general description of the preferred stock we may offer. Each time we sell preferred stock, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the preferred stock, including, to the extent applicable:

In order to qualify as a REIT under the Internal Revenue Code, our shares of capital stock must be beneficially owned by 100 or more persons during at least 335 days of a taxable year of 12 months or during a proportionate part of a shorter taxable year. Also no more than 50% of the value of our outstanding shares of capital stock may be owned, directly or constructively, by five or fewer individuals (as defined in the Internal Revenue Code to include certain entities) during the second half of any calendar year.

Our amended and restated certificate of incorporation, subject to certain exceptions, contains restrictions on the number of shares of our common stock and our capital stock that a person may own and may prohibit certain entities from owning our shares. Our amended and restated certificate of incorporation provides that (subject to certain exceptions described below) no person may beneficially or constructively own, or be deemed to own by virtue of the attribution provisions of the Internal Revenue Code, more than 9.8% in value or in number of shares, whichever is more restrictive, of either our common stock or our capital stock. Pursuant to our amended and restated certificate of incorporation, our Board of Directors has the power to increase or decrease the percentage of our common stock and our capital stock that a person may beneficially or constructively own. However, any decreased stock ownership limit will not apply to any person whose percentage ownership of our common stock or our capital stock, as the case may be, is in excess of such decreased stock ownership limit until that person’s percentage ownership of our common stock or our capital stock, as the case may be, equals or falls below the decreased stock ownership limit. Until such a person’s percentage ownership of our common stock or our capital stock, as the case may be, falls below such decreased stock ownership limit, any further acquisition of common stock will be in violation of the decreased stock ownership limit. If our Board of Directors changes the stock ownership limit, it will (i) notify each stockholder of record of any such change, and (ii) publicly announce any such change, in each case at least 30 days prior to the effective date of such change.

Our amended and restated certificate of incorporation also prohibits any person from beneficially or constructively owning shares of our capital stock that would result in our being “closely held” under Section 856(h) of the Internal Revenue Code or otherwise cause us to fail to qualify as a REIT and from transferring shares of our capital stock if the transfer would result in our capital stock being beneficially owned

by fewer than 100 persons. In addition, no such person may own an interest in any tenant that would cause us to own, actually or constructively, more than a 9.9% interest in such tenant. Any person who acquires or attempts or intends to acquire beneficial or constructive ownership of shares of our capital stock that will or may violate any of the foregoing restrictions on transferability and ownership, or who is the intended transferee of shares of our capital stock that are transferred to the trust (as described below), is required to give written notice immediately to us and provide us with such other information as we may request in order to determine the effect of such transfer on our qualification as a REIT. The foregoing restrictions on transferability and ownership will not apply if our Board of Directors determines that it is no longer in our best interests to attempt to qualify, or to continue to qualify, as a REIT.

Our Board of Directors, in its sole discretion, may exempt a person from the foregoing restrictions. The person seeking an exemption must provide to our Board of Directors such conditions, representations and undertakings as our Board of Directors may deem reasonably necessary to conclude that granting the exemption will not cause us to lose our qualification as a REIT. Our Board of Directors may also require a ruling from the Internal Revenue Service (the “IRS”) or an opinion of counsel in order to determine or ensure our qualification as a REIT in the context of granting such exemptions. Our Board of Directors has granted American Capital an exemption from these restrictions, subject to the continued accuracy of American Capital’s representation to us, among others, that no person or entity beneficially or constructively owns more than 9.8% (in value or number, whichever is more restrictive) of any class or series of our capital stock as a result of any such person or entity’s beneficial or constructive ownership of capital stock of American Capital, taken together with any shares of our capital stock owned by any such person or entity.

Any attempted transfer of our capital stock which, if effective, would result in a violation of the foregoing restrictions will cause the number of shares causing the violation (rounded up to the nearest whole share) to be automatically transferred to a trust for the exclusive benefit of one or more charitable beneficiaries, and the proposed transferee will not acquire any rights in such shares. The automatic transfer will be deemed to be effective as of the close of business on the business day (as defined in our amended and restated certificate of incorporation) prior to the date of the transfer. If, for any reason, the transfer to the trust does not occur or would not prevent a violation of the restrictions on ownership contained in our amended and restated certificate of incorporation, our amended and restated certificate of incorporation provides that the purported transfer will be void ab initio. Shares of our capital stock held in the trust will be issued and outstanding shares. The proposed transferee will not benefit economically from ownership of any shares of our capital stock held in the trust, will have no rights to dividends and no rights to vote or other rights attributable to the shares of capital stock held in the trust. The trustee of the trust will have all voting rights and rights to dividends or other distributions with respect to shares held in the trust. These rights will be exercised for the exclusive benefit of the charitable beneficiary. Any dividend or other distribution paid prior to our discovery that shares of capital stock have been transferred to the trust will be paid by the recipient to the trustee upon demand. Any dividend or other distribution authorized but unpaid will be paid when due to the trustee. Any dividend or distribution paid to the trustee will be held in trust for the charitable beneficiary. Subject to Delaware law, the trustee will have the authority to rescind as void any vote cast by the proposed transferee prior to our discovery that the shares have been transferred to the trust and to recast the vote in accordance with the desires of the trustee acting for the benefit of the charitable beneficiary. However, if we have already taken irreversible corporate action, then the trustee will not have the authority to rescind and recast the vote.

Within 20 days of receiving notice from us that shares of our capital stock have been transferred to the trust, the trustee will sell the shares to a person designated by the trustee, whose ownership of the shares will not violate the above ownership limitations. Upon such sale, the interest of the charitable beneficiary in the shares sold will terminate and the trustee will distribute the net proceeds of the sale to the proposed transferee and to the charitable beneficiary as follows: the proposed transferee will receive the lesser of (1) the price paid by the proposed transferee for the shares or, if the proposed transferee did not give value for the shares in connection with the event causing the shares to be held in the trust (e.g., a gift, devise or other similar transaction), the market price (as defined in our amended and restated certificate of incorporation) of the shares on the day of the

event causing the shares to be held in the trust and (2) the price received by the trustee from the sale or other disposition of the shares. Any net sale proceeds in excess of the amount payable to the proposed transferee will be paid immediately to the charitable beneficiary. If, prior to our discovery that shares of our capital stock have been transferred to the trust, the shares are sold by the proposed transferee, then (1) the shares shall be deemed to have been sold on behalf of the trust and (2) to the extent that the proposed transferee received an amount for the shares that exceeds the amount the proposed transferee was entitled to receive, the excess shall be paid to the trustee upon demand.

In addition, shares of our capital stock held in the trust will be deemed to have been offered for sale to us, or our designee, at a price per share equal to the lesser of the price per share in the transaction that resulted in the transfer to the trust (or, in the case of a devise or gift, the market price at the time of the devise or gift) and the market price on the date we, or our designee, accept the offer. We will have the right to accept the offer until the trustee has sold the shares. Upon a sale to us, the interest of the charitable beneficiary in the shares sold will terminate and the trustee will distribute the net proceeds of the sale to the proposed transferee.

Every owner of more than 5% (or such lower percentage as required by the Internal Revenue Code or the regulations promulgated thereunder) in number or in value of all classes or series of our capital stock, including shares of our common stock, within 30 days after the end of each taxable year, will be required to give written notice to us stating the name and address of such owner, the number of shares of each class and series of shares of our capital stock that the owner beneficially owns and a description of the manner in which the shares are held. Each owner shall provide to us such additional information as we may request to determine the effect, if any, of the beneficial ownership on our qualification as a REIT and to ensure compliance with the ownership limitations. In addition, each such owner shall, upon demand, be required to provide to us such information as we may request, in good faith, to determine our qualification as a REIT and to comply with the requirements of any taxing authority or governmental authority or to determine such compliance and to ensure compliance with the 9.8% ownership limitations in our amended and restated certificate of incorporation.

These ownership limitations could delay, defer or prevent a transaction or a change in control that might involve a premium price for our common stock or might otherwise be in the best interests of our stockholders.

Anti-Takeover Effects of Delaware Law and Our Amended and Restated Certificate of Incorporation and By-laws

Our amended and restated certificate of incorporation and by-laws contain provisions that are intended to enhance the likelihood of continuity and stability in the composition of the Board of Directors and that may have the effect of delaying, deferring or preventing a future takeover or change in control of our Company unless the takeover or change in control is approved by our Board of Directors. In addition to the above-described restrictions regarding the transfer and ownership of our capital stock, these provisions include the following:

Our amended and restated certificate of incorporation provides that stockholder action may not be taken by written consent in lieu of a meeting and that stockholder action may be taken only at an annual or special meeting of stockholders.

Our by-laws provide that, except as otherwise required by law, special meetings of our stockholders can only be called by our president, pursuant to a resolution adopted by a majority of our Board of Directors or a committee of the Board of Directors that has been duly designated by the Board of Directors and whose powers and authority include the power to call such meetings, or by the chairman of our Board of Directors. Stockholders are not permitted to call a special meeting or to require our Board of Directors to call a special meeting.

Our amended and restated certificate of incorporation provides that members of our Board of Directors may only be removed for cause, and only with the affirmative vote of the holders of at least 66% of the combined voting power of all the shares of all classes of our capital stock entitled to vote generally in the election of directors. Our by-laws provide that only our Board of Directors may fill vacant directorships. These provisions would prevent a stockholder from gaining control of our Board of Directors by removing incumbent directors and filling the resulting vacancies with such stockholder’s own nominees.

The General Corporation Law of the State of Delaware, or DGCL, provides generally that the affirmative vote of a majority of the outstanding shares entitled to vote is required to amend or repeal a corporation’s certificate of incorporation or by-laws, unless the certificate of incorporation requires a greater percentage. Our amended and restated certificate of incorporation generally requires the approval of both a majority of the combined voting power of all the classes of shares of our capital stock entitled to vote generally in the election of directors and a majority of the members of our Board of Directors to amend any provisions of our certificate of incorporation, except that provisions of our amended and restated certificate of incorporation relating to the powers, numbers, classes, elections, terms and removal of our directors, as well as the ability to fill vacancies on our Board of Directors requires the affirmative vote of at least 66% of the combined voting power of all the shares of all classes of our capital stock entitled to vote generally in the election of directors. In addition, our amended and restated certificate of incorporation (i) grants our Board of Directors the authority to amend and repeal our by-laws without a stockholder vote in any manner not inconsistent with the DGCL and (ii) requires that stockholders may only amend our by-laws with the affirmative vote of 66% of the combined voting power of all the shares of all classes of our capital stock entitled to vote generally in the election of directors.

The foregoing provisions of our amended and restated certificate of incorporation and by-laws could discourage potential acquisition proposals and could delay or prevent a change in control. These provisions are intended to enhance the likelihood of continuity and stability in the composition of our Board of Directors and in the policies formulated by our Board of Directors and to discourage certain types of transactions that may involve an actual or threatened change of control. These provisions are designed to reduce our vulnerability to an unsolicited acquisition proposal. The provisions also are intended to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and, as a consequence, they also may inhibit fluctuations in the market price of our common stock that could result from actual or rumored takeover attempts. Such provisions also may have the effect of preventing changes in our management or delaying or preventing a transaction that might benefit you or other minority stockholders.

We will not be subject to Section 203 of the DGCL, an anti-takeover law. In general, Section 203 prohibits a publicly-held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years following the date the person became an interested stockholder, unless (with certain exceptions) the “business combination” or the transaction in which the person became an interested stockholder is approved in a prescribed manner. Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. Generally, an “interested stockholder” is a person who, together with affiliates and associates, owns (or within three years prior to the determination of interested stockholder status, did own) 15% or more of a corporation’s voting stock. In our original certificate of incorporation, we have elected not to be bound by Section 203.

Our amended and restated certificate of incorporation and by-laws provide indemnification for our directors and officers to the fullest extent permitted by the DGCL, except that such directors and officers will not be

indemnified to the extent that any such person has committed willful misfeasance, bad faith, gross negligence or reckless disregard involved in the conduct of such person’s duty to or for us. In addition, as permitted by Delaware law, our amended and restated certificate of incorporation includes provisions that eliminate the personal liability of our directors for monetary damages resulting from breaches of certain fiduciary duties as a director. The effect of this provision is to restrict our rights and the rights of our stockholders in derivative suits to recover monetary damages against a director for breach of fiduciary duties as a director, except that a director will be personally liable to the extent such director has committed willful misfeasance, bad faith, gross negligence or reckless disregard of such director’s duties involved in the conduct of the office of director.

These provisions may be held not to be enforceable for violations of the federal securities laws of the United States.

The transfer agent and registrar for our shares of common stock is Computershare Trust Company, N.A. The principal business address of Computershare Trust Company, N.A. is P.O. Box 43010, Providence, Rhode Island 02940-3010.

The following is a summary of the material U.S. federal income tax consequences of an investment in common stock of American Capital Agency Corp. For purposes of this section under the heading “Federal Income Tax Considerations,” references to “American Capital Agency Corp.,” “we,” “our” and “us” mean only American Capital Agency Corp. and not its subsidiaries or other lower-tier entities, except as otherwise indicated. This summary is based upon the Internal Revenue Code, the regulations promulgated by the U.S. Treasury Department (“Treasury”), rulings and other administrative pronouncements issued by the IRS, and judicial decisions, all as currently in effect, and all of which are subject to differing interpretations or to change, possibly with retroactive effect. No assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to any of the tax consequences described below. We have not sought and will not seek an advance ruling from the IRS regarding any matter discussed in this prospectus. The summary is also based upon the assumption that we will operate American Capital Agency Corp. and its subsidiaries and affiliated entities in accordance with their applicable organizational documents or partnership agreements. This summary is for general information only and is not tax advice. It does not purport to discuss all aspects of U.S. federal income taxation that may be important to a particular investor in light of its investment or tax circumstances or to investors subject to special tax rules, such as:

This summary assumes that investors will hold their common stock as a capital asset, which generally means as property held for investment.

The federal income tax treatment of holders of our common stock depends in some instances on determinations of fact and interpretations of complex provisions of U.S. federal income tax law for which no clear precedent or authority may be available. In addition, the tax consequences to any particular stockholder of holding our common stock will depend on the stockholder’s particular tax circumstances. You are urged to consult your tax advisor regarding the federal, state, local, and foreign income and other tax consequences to you in light of your particular investment or tax circumstances of acquiring, holding, exchanging, or otherwise disposing of our common stock.

We will be taxed as a REIT, commencing with our initial taxable year ended December 31, 2008, upon the filing of our federal income tax return for such year. We believe that we have been organized and have operated in such a manner that permits us to satisfy the requirements for taxation as a REIT under the applicable provisions of the Internal Revenue Code.

The law firm of Skadden, Arps, Slate, Meagher & Flom LLP has acted as our tax counsel in connection with the filing of this registration statement. In connection with the filing of this registration statement, we expect to receive an opinion of Skadden, Arps, Slate, Meagher & Flom LLP to the effect that, commencing with our initial taxable year, we have been organized and operated in conformity with the requirements for qualification and taxation as a REIT under the Internal Revenue Code, and that our actual method of operation has enabled, and our proposed method of operation will continue to enable, us to meet the requirements for qualification and taxation as a REIT. It must be emphasized that the opinion of Skadden, Arps, Slate, Meagher & Flom LLP will be based on various assumptions relating to our organization and operation and will be conditioned upon fact-based representations and covenants made by our management regarding our organization, assets, and income, and the present and future conduct of our business operations. While we intend to operate so that we continue to qualify as a REIT, given the highly complex nature of the rules governing REITs, the ongoing importance of factual determinations, and the possibility of future changes in our circumstances, no assurance can be given by Skadden, Arps, Slate, Meagher & Flom LLP or by us that we will qualify as a REIT for any particular year. The opinion will be expressed as of the date issued and will not cover subsequent periods. Skadden, Arps, Slate, Meagher & Flom LLP will have no obligation to advise us or our stockholders of any subsequent change in the matters stated, represented or assumed, or of any subsequent change in the applicable law. You should be aware that opinions of counsel are not binding on the IRS, and no assurance can be given that the IRS will not challenge the conclusions set forth in such opinions.

For tax years through 2010, most domestic stockholders that are individuals, trusts or estates are taxed on corporate dividends at a maximum rate of 15% (the same as long-term capital gains). With limited exceptions, however, dividends from us or from other entities that are taxed as REITs are generally not eligible for this rate and will continue to be taxed at rates applicable to ordinary income, which will be as high as 35% through 2010. See “—Taxation of Stockholders—Taxation of Taxable Domestic Stockholders—Distributions.”

In any year in which we qualify as a REIT, we will nonetheless be subject to federal tax in the following circumstances:

The Internal Revenue Code defines a REIT as a corporation, trust or association:

In addition, a corporation generally may not elect to become a REIT unless its taxable year is the calendar year. We have adopted December 31 as our year-end, and thereby satisfy this requirement.

The Internal Revenue Code provides relief from violations of the REIT gross income requirements, as described below under “—Income Tests,” in cases where a violation is due to reasonable cause and not to willful neglect, and other requirements are met, including the payment of a penalty tax that is based upon the magnitude of the violation. In addition, certain provisions of the Internal Revenue Code extend similar relief in the case of certain violations of the REIT asset requirements (see “—Asset Tests” below) and other REIT requirements, again provided that the violation is due to reasonable cause and not willful neglect, and other conditions are met, including the payment of a penalty tax. If we fail to satisfy any of the various REIT requirements, there can be no assurance that these relief provisions would be available to enable us to maintain our qualification as a REIT, and, if such relief provisions are available, the amount of any resultant penalty tax could be substantial.

We are not treated as holding the assets of our TRS or other taxable subsidiary corporation or as receiving any income that the subsidiary earns. Rather, the stock issued by a taxable subsidiary to us is an asset in our hands, and we treat the dividends paid to us from such taxable subsidiary, if any, as income. This treatment can affect our income and asset test calculations, as described below. Because we do not include the assets and income of TRSs or other taxable subsidiary corporations in determining our compliance with the REIT requirements, we may use such entities to undertake indirectly activities that the REIT rules might otherwise preclude us from doing directly or through pass-through subsidiaries. For example, we may use TRSs or other taxable subsidiary corporations to conduct activities that give rise to certain categories of income such as management fees or to conduct activities that, if conducted by us directly, would be treated in our hands as prohibited transactions.

We may continue to purchase agency securities through “to-be-announced” forward contacts (“TBAs”) and may recognize income or gains from the disposition of those TBAs, through dollar roll transactions or otherwise. There is no direct authority with respect to the qualification of income or gains from dispositions of TBAs as gains from the sale of real property (including interests in real property and interests in mortgages on real property) or other qualifying income for purposes of the 75% gross income test and we would not treat these

items as such unless we receive a reasoned, written opinion (within the meaning of applicable Treasury regulations) of our counsel that such income and gains should be treated as such. Consequently, our ability to enter into dollar roll transactions and other dispositions of TBAs could be limited. Moreover, even if we were to receive the opinion of counsel described above, it is possible that the IRS could assert that such income is not qualifying income. In the event that such income were determined not to be qualifying for the 75% gross income test, we could be subject to a penalty tax or we could fail to qualify as a REIT if such income when added to any other non-qualifying income exceeded 25% of our gross income.

If we fail to satisfy one or both of the 75% or 95% gross income tests for any taxable year, including as a result of income and gains from the disposition of TBAs, we may still qualify as a REIT for such year if we are entitled to relief under applicable provisions of the Internal Revenue Code. These relief provisions will be generally available if (1) our failure to meet these tests was due to reasonable cause and not due to willful neglect and (2) following our identification of the failure to meet the 75% or 95% gross income test for any taxable year, we file a schedule with the IRS setting forth each item of our gross income for purposes of the 75% or 95% gross income test for such taxable year in accordance with Treasury regulations yet to be issued. It is not possible to state whether we would be entitled to the benefit of these relief provisions in all circumstances. If these relief provisions are inapplicable to a particular set of circumstances, we will not qualify as a REIT. As discussed above under “—Taxation of REITs in General,” even where these relief provisions apply, the Internal Revenue Code imposes a tax based upon the amount by which we fail to satisfy the particular gross income test.

Second, the value of any one issuer’s securities that we own may not exceed 5% of the value of our total assets.

Certain securities will not cause a violation of the 10% asset test described above. Such securities include instruments that constitute “straight debt,” which includes, among other things, securities having certain contingency features. A security does not qualify as “straight debt” where a REIT (or a controlled TRS of the REIT) owns other securities of the same issuer which do not qualify as straight debt, unless the value of those other securities constitute, in the aggregate, 1% or less of the total value of that issuer’s outstanding securities. In addition to straight debt, the Internal Revenue Code provides that certain other securities will not violate the 10% asset test. Such securities include (1) any loan made to an individual or an estate, (2) certain rental agreements pursuant to which one or more payments are to be made in subsequent years (other than agreements between a REIT and certain persons related to the REIT under attribution rules), (3) any obligation to pay rents from real property, (4) securities issued by governmental entities that are not dependent in whole or in part on the profits of (or payments made by) a non-governmental entity, (5) any security (including debt securities) issued by another REIT, and (6) any debt instrument issued by a partnership if the partnership’s income is of a nature that it would satisfy the 75% gross income test described above under “—Income Tests.” In applying the 10% asset test, a debt security issued by a partnership is not taken into account to the extent, if any, of the REIT’s proportionate interest in the equity and certain debt securities issued by that partnership.

We may, continue to purchase agency securities through TBAs. There is no direct authority with respect to the qualification of TBAs as real estate assets or Government securities for purposes of the 75% asset test and we would not treat TBAs as such unless we receive a reasoned, written opinion (within the meaning of applicable Treasury regulations) of our counsel that TBAs should be treated as such. Consequently, our ability to purchase TBAs could be limited. Moreover, even if we were to receive the opinion of counsel described above, it is possible that the IRS could assert that TBAs are not qualifying assets. In the event that TBAs were determined not to be qualifying for the 75% asset test, we could be subject to a penalty tax or we could fail to qualify as a REIT if such assets when added to any other non-qualifying assets exceeded 25% of our gross assets.

However, certain relief provisions are available to allow REITs to satisfy the asset requirements or to maintain REIT qualification notwithstanding certain violations of the asset and other requirements. One such provision allows a REIT which fails one or more of the asset requirements to nevertheless maintain its REIT qualification if (1) the REIT provides the IRS with a description of each asset causing the failure, (2) the failure is due to reasonable cause and not willful neglect, (3) the REIT pays a tax equal to the greater of (a) $50,000 per failure, and (b) the product of the net income generated by the assets that caused the failure multiplied by the highest applicable corporate tax rate (currently 35%), and (4) the REIT either disposes of the assets causing the failure within six months after the last day of the quarter in which it identifies the failure, or otherwise satisfies the relevant asset tests within that time frame.

In order to qualify as a REIT, we are required to distribute dividends, other than capital gain dividends, to our stockholders in an amount at least equal to:

(1) 90% of our “REIT taxable income,” computed without regard to our net capital gains and the deduction for dividends paid, and

(2) 90% of our net income, if any, (after tax) from foreclosure property (as described below), minus

subsidiaries, and (b) our inclusion of items in income for federal income tax purposes. Other potential sources of non-cash taxable income include:

Foreclosure property is real property and any personal property incident to such real property (1) that we acquire as the result of having bid in the property at foreclosure, or having otherwise reduced the property to ownership or possession by agreement or process of law, after a default (or upon imminent default) on a lease of the property or a mortgage loan held by us and secured by the property, (2) for which we acquired the related loan or lease at a time when default was not imminent or anticipated, and (3) with respect to which we made a proper election to treat the property as foreclosure property. We generally will be subject to tax at the maximum corporate rate (currently 35%) on any net income from foreclosure property, including any gain from the disposition of the foreclosure property, other than income that would otherwise be qualifying income for purposes of the 75% gross income test. Any gain from the sale of property for which a foreclosure property election has been made will not be subject to the 100% tax on gains from prohibited transactions described above, even if the property would otherwise constitute inventory or dealer property. Because we will invest exclusively in agency securities, we do not anticipate receiving any income from foreclosure property that does not qualify for purposes of the 75% gross income test.

derivative instruments such as interest rate swap contracts, interest rate cap or floor contracts, futures or forward contracts, and options. Except to the extent provided by Treasury regulations, any income from a hedging transaction we enter into (1) in the normal course of our business primarily to manage risk of interest rate or price changes or currency fluctuations with respect to borrowings made or to be made, or ordinary obligations incurred or to be incurred, to acquire or carry real estate assets, which is clearly identified as specified in Treasury regulations before the close of the day on which it was acquired, originated, or entered into, including gain from the sale or disposition of such a transaction, and (2) primarily to manage risk of currency fluctuations with respect to any item of income or gain that would be qualifying income under the 75% or 95% income tests which is clearly identified as such before the close of the day on which it was acquired, originated, or entered into, will not constitute gross income for purposes of the 75% or 95% gross income test. To the extent that we enter into other types of hedging transactions, the income from those transactions is likely to be treated as non-qualifying income for purposes of both of the 75% and 95% gross income tests. We intend to structure any hedging transactions in a manner that does not jeopardize our qualification as a REIT. We may conduct some or all of our hedging activities (including hedging activities relating to currency risk) through our TRS or other corporate entity, the income from which may be subject to federal income tax, rather than by participating in the arrangements directly or through pass-through subsidiaries. No assurance can be given, however, that our hedging activities will not give rise to income that does not qualify for purposes of either or both of the REIT gross income tests, or that our hedging activities will not adversely affect our ability to satisfy the REIT qualification requirements.

If we fail to qualify for taxation as a REIT in any taxable year, and the relief provisions described above do not apply, we would be subject to tax, including any applicable alternative minimum tax, on our taxable income at regular corporate rates. We cannot deduct distributions to stockholders in any year in which we are not a REIT, nor would we be required to make distributions in such a year. In this situation, to the extent of current and accumulated earnings and profits, distributions to most domestic stockholders that are individuals, trusts and estates will generally be taxable at capital gains rates (through 2010). In addition, subject to the limitations of the Internal Revenue Code, corporate distributees may be eligible for the dividends received deduction. Unless we are entitled to relief under specific statutory provisions, we would also be disqualified from re-electing to be taxed as a REIT for the four taxable years following the year during which we lost qualification. It is not possible to state whether, in all circumstances, we would be entitled to this statutory relief.

Distributions. So long as we qualify as a REIT, the distributions that we make to our taxable domestic stockholders out of current or accumulated earnings and profits that we do not designate as capital gain dividends will generally be taken into account by stockholders as ordinary income and will not be eligible for the dividends received deduction for corporations. With limited exceptions, our dividends are not eligible for taxation at the preferential income tax rates (i.e., the 15% maximum federal rate through 2010) for qualified dividends received by most domestic stockholders that are individuals, trusts and estates from taxable C corporations. Such stockholders, however, are taxed at the preferential rates on dividends designated by and received from REITs to the extent that the dividends are attributable to:

Distributions that we designate as capital gain dividends will generally be taxed to our stockholders as long-term capital gains, to the extent that such distributions do not exceed our actual net capital gain for the taxable year, without regard to the period for which the stockholder that receives such distribution has held its stock. We may elect to retain and pay taxes on some or all of our net long-term capital gains, in which case provisions of the Internal Revenue Code will treat our stockholders as having received, solely for tax purposes, our undistributed capital gains, and the stockholders will receive a corresponding credit for taxes that we paid on such undistributed capital gains. See “Taxation of American Capital Agency Corp.—Annual Distribution Requirements.” Corporate stockholders may be required to treat up to 20% of some capital gain dividends as ordinary income. Long-term capital gains are generally taxable at maximum federal rates of 15% (through 2010) in the case of stockholders that are individuals, trusts and estates, and 35% in the case of stockholders that are corporations. Capital gains attributable to the sale of depreciable real property held for more than 12 months are subject to a 25% maximum federal income tax rate for taxpayers who are taxed as individuals, to the extent of previously claimed depreciation deductions.

Dispositions of American Capital Agency Corp. Stock. In general, capital gains recognized by individuals, trusts and estates upon the sale or disposition of our stock will be subject to a maximum federal income tax rate of 15% (through 2010) if the stock is held for more than one year, and will be taxed at ordinary income rates (of up to 35% through 2010) if the stock is held for one year or less. Gains recognized by stockholders that are corporations are subject to federal income tax at a maximum rate of 35%, whether or not such gains are classified as long-term capital gains. Capital losses recognized by a stockholder upon the disposition of our stock that was held for more than one year at the time of disposition will be considered long-term capital losses, and are generally available only to offset capital gain income of the stockholder but not ordinary income (except in the case of individuals, who may offset up to $3,000 of ordinary income each year). In addition, any loss upon a sale or exchange of shares of our stock by a stockholder who has held the shares for six months or less, after applying holding period rules, will be treated as a long-term capital loss to the extent of distributions that we make that are required to be treated by the stockholder as long-term capital gain.

“reportable transactions” could apply, with a resulting requirement to separately disclose the loss-generating transaction to the IRS. These regulations, though directed towards “tax shelters,” are broadly written and apply to transactions that would not typically be considered tax shelters. The Internal Revenue Code imposes significant penalties for failure to comply with these requirements. You should consult your tax advisor concerning any possible disclosure obligation with respect to the receipt or disposition of our stock or securities or transactions that we might undertake directly or indirectly. Moreover, you should be aware that we and other participants in the transactions in which we are involved (including their advisors) might be subject to disclosure or other requirements pursuant to these regulations.

The following discussion is based on current law, and is for general information only. It addresses only selected, and not all, aspects of U.S. federal income and estate taxation.

REIT “closely-held” test, and (2) either (i) one pension trust owns more than 25% of the value of our stock, or (ii) one or more pension trusts, each individually holding more than 10% of the value of our stock, collectively owns more than 50% of the value of our stock. Certain restrictions on ownership and transfer of our stock generally should prevent a tax-exempt entity from owning more than 10% of the value of our stock and generally should prevent us from becoming a pension-held REIT.

Tax-exempt stockholders are urged to consult their tax advisors regarding the federal, state, local and foreign income and other tax consequences of owning American Capital Agency Corp. stock.

The present federal income tax treatment of REITs may be modified, possibly with retroactive effect, by legislative, judicial or administrative action at any time. The REIT rules are constantly under review by persons involved in the legislative process and by the IRS and the U.S. Treasury Department which may result in statutory changes as well as revisions to regulations and interpretations. For example, Congress is considering proposals that would delay the scheduled increase in the maximum tax rates applicable to most domestic taxpayers that are individuals, trusts, and estates on qualified dividend income and long term capital gains, for taxable years beginning after December 31, 2010, to 39.6% and 20% respectively. No assurance can be given as to whether, or in what form, the proposals described above (or any other proposals affecting REITs or their stockholders) will be enacted. Changes to the federal tax laws and interpretations thereof could adversely affect an investment in our common stock.

Under recently enacted legislation, for taxable years beginning after December 31, 2012, certain U.S. holders who are individuals, estates or trusts and whose income exceeds certain thresholds will be required to pay a 3.8% Medicare tax on dividend and other income, including capital gains from the sale or other disposition of our common stock.

Recently enacted legislation will require, after December 31, 2012, withholding at a rate of 30% on dividends in respect of, and gross proceeds from the sale of, our common stock held by or through certain foreign financial institutions (including investment funds), unless such institution enters into an agreement with the Secretary of the Treasury to report, on an annual basis, information with respect to shares in the institution held by certain United States persons and by certain non-U.S. entities that are wholly or partially owned by United States persons and to withhold on certain payments. Accordingly, the entity through which our common stock is held will affect the determination of whether such withholding is required. Similarly, dividends in respect of, and gross proceeds from the sale of, our common stock held by an investor that is a non-financial non-U.S. entity will be subject to withholding at a rate of 30%, unless such entity either (i) certifies to us that such entity does not have any “substantial United States owners” or (ii) provides certain information regarding the entity’s “substantial United States owners,” which we will in turn provide to the Secretary of the Treasury. We will not pay any additional amounts to stockholders in respect of any amounts withheld. Non-U.S. holders are encouraged to consult with their tax advisors regarding the possible implications of the legislation on their investment in our common stock.

Unless otherwise indicated in the applicable prospectus supplement, Skadden, Arps, Slate, Meagher & Flom LLP, New York, New York, will provide opinions regarding the authorization and validity of the Securities and certain federal income tax matters. Skadden, Arps, Slate, Meagher & Flom LLP, New York may also provide opinions regarding certain other matters. Any underwriters will also be advised about legal matters by their own counsel, who will be identified in the prospectus supplement.

The consolidated financial statements of American Capital Agency Corp. appearing in American Capital Agency Corp.’s Annual Report (Form 10-K) for the year ended December 31, 2009, and the effectiveness of American Capital Agency Corp.’s internal control over financial reporting as of December 31, 2009 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

We file annual, quarterly, and current reports, proxy statements and other information with the SEC. You may read and copy any reports or other information that we file with the SEC at the SEC’s Public Reference Room located at 100 F Street, N.E., Washington D.C. 20549. You may also receive copies of these documents upon payment of a duplicating fee, by writing to the SEC’s Public Reference Room. Please call the SEC at 1-800-SEC-0330 for further information on the Public Reference Room in Washington D.C. Our Securities and Exchange Commission filings, including our registration statement, are also available to you, free of charge, on the Securities and Exchange Commission’s website at www.sec.gov. You may also obtain additional information by visiting our website at www.agnc.com.

The SEC allows us to “incorporate by reference” information into this prospectus which has been previously filed, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, except for any information superseded by information in this prospectus. We have filed the documents listed below with the SEC (File No. 001-34057) under the Exchange Act and these documents are incorporated herein by reference:

All documents that we file (but not those that we furnish) with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of the initial registration statement of which this prospectus is a part and prior to effectiveness of the registration statement will be deemed to be incorporated by reference into this prospectus and will automatically update and supersede the information in this prospectus, and any previously filed document. In addition, all documents that we file (but not those that we furnish) with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus and prior to the termination of the offering of shares hereby will be deemed to be incorporated by reference into this prospectus and will automatically update and supersede the information in this prospectus, any accompanying prospectus supplement and any previously filed document.

We will provide to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, a copy of any or all of the information that has been incorporated by reference in this prospectus but not delivered with this prospectus (other than the exhibits to such documents which are not specifically incorporated by reference herein); we will provide this information at no cost to the requester upon written or oral request to American Capital Agency Corp., 2 Bethesda Metro Center, 14^th Floor, Bethesda, MD 20814, telephone number (301) 968-9300.



Title of each class of securities to be registered	Amount to be registered		Proposed maximum offering price per unit		Proposed maximum aggregate offering price		Amount of registration fee⁽¹⁾
Common Stock		71,150,000	$	29.00	$	2,063,350,000	$	236,460


BofA Merrill Lynch		Citigroup		Goldman, Sachs & Co.		J.P. Morgan		UBS Investment Bank


	Page
About This Prospectus Supplement		S-i
Cautionary Statement Regarding Forward Looking Statements		S-ii
Summary		S-1
The Offering		S-3
Use of Proceeds		S-4
Risk Factors		S-4
Distributions		S-5
Capitalization		S-6
Supplement to Federal Income Tax Considerations		S-7
Underwriting (Potential Conflicts of Interest)		S-25
Legal Matters		S-29
Experts		S-29
Where You Can Find More Information		S-29
Incorporation of Certain Documents by Reference		S-30

Prospectus

About this Prospectus		ii
Forward Looking Statements		iii
Prospectus Summary		1
Risk Factors		3
Use of Proceeds		3
Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends		3
Plan of Distribution		4
Description of Securities		6
Federal Income Tax Considerations		12
Legal Matters		29
Experts		29
Where You Can Find More Information		29
Incorporation of Certain Documents by Reference		29


	Cash Distributions Declared Per Share of Common Stock

2012
First quarter	$	1.25

2011
Fourth quarter	$	1.40
Third quarter	$	1.40
Second quarter	$	1.40
First quarter	$	1.40

2010
Fourth quarter	$	1.40
Third quarter	$	1.40
Second quarter	$	1.40
First quarter	$	1.40

2009
Fourth quarter	$	1.40
Third quarter	$	1.40
Second quarter	$	1.50
First quarter	$	0.85

2008
Fourth quarter	$	1.20
Third quarter	$	1.00
Second quarter⁽¹⁾	$	0.31


	As of December 31, 2011 (in thousands)
	Actual			As adjusted for this offering and shares sold under a Sales Agreement with Mitsubishi UFJ Securities (USA), Inc. ⁽¹⁾
Assets:
Cash and cash equivalents	$	1,366,895		$	3,306,673

Stockholders’ equity:
Preferred stock: par value $.01 per share; 10,000 shares authorized, none issued and outstanding		—			—
Common stock: par value $.01 per share; 300,000 shares authorized, 224,150 and 290,843 shares issued and outstanding on an actual and adjusted basis including this offering and shares sold under a Sales Agreement with Mitsubishi UFJ Securities (USA), Inc., respectively		2,241			2,908
Additional paid-in capital		5,937,190			7,876,301
Retained earnings		(37,922	)		(37,922	)
Accumulated other comprehensive income		310,294			310,294

Total stockholders’ equity	$	6,211,803		$	8,151,581


Underwriters	Number of Shares
Merrill Lynch, Pierce Fenner & Smith Incorporated		11,284,000
Citigroup Global Markets Inc.		11,284,000
Goldman, Sachs & Co.		11,284,000
J.P. Morgan Securities LLC		11,284,000
UBS Securities LLC		11,284,000
Barclays Capital Inc.		2,790,000
Nomura Securities International, Inc.		2,790,000

Total		62,000,000


	Page
About this Prospectus		ii
Forward-Looking Statements		iii
Prospectus Summary		1
Risk Factors		3
Use of Proceeds		3
Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends		3
Plan of Distribution		4
Description of Securities		6
Federal Income Tax Considerations		12
Legal Matters		29
Experts		29
Where You Can Find More Information		29
Incorporation of Certain Documents by Reference		29


	For the period May 20, 2008 (date operations commenced) through December 31, 2008	Year ended December 31, 2009	Six months ended June 30, 2010
Ratio of earnings to combined fixed charges and preferred stock dividends	2.4	3.7	3.7


Barclays Capital		Nomura