Subsidies in a Context of Efficient Markets: A New Framework for Evaluating the Role of Fannie Mae

26 Pages Posted: 8 Nov 2005

See all articles by Michael C. Fratantoni

Michael C. Fratantoni

Washington Mutual; Foster School of Business, University of Washington

Peter Niculescu

Fannie Mae

Date Written: November 2, 2005


Fannie Mae and Freddie Mac have been the focus of extensive Congressional, academic, and journalistic scrutiny in recent years. Much of this attention has been due to a claim that their shareholders and employees benefit inordinately from the companies' Congressional charter and that this charter permits unlimited portfolio growth. The impact of their status has been labeled an "implicit subsidy" in several controversial studies. The theoretical underpinning of the "implicit subsidy" observation is an application of the standard microeconomic model of subsidies for producers of tangible goods. The standard "goods" model concludes that the subsidized producer will capture all or most of the subsidy and will expand without limit until it becomes a monopolist.

The "goods" model cannot be applied to financial assets. Because financial markets are efficient, Fannie Mae is unable to benefit through its retained portfolio from any lowering of debt yields because mortgage backed security (MBS) yields will be lowered by at least the same amount. Selling agency debt to buy agency MBS is accomplished at prices set in a broad and competitive market. The spread between these two securities reflects the prepayment risk in mortgages and liquidity differences between MBS and debt. For Fannie Mae's portfolio to earn above-normal returns, the spread between MBS and debt would have to be in some way too large. Because many investors are able to trade in these securities to capture any deviations from a market rate of return given the inherent risk, all abnormal returns are traded away. In fact, the sale of agency debt to finance MBS redistributes risks to those investors best able to manage them and thus lowers risk premiums, causing MBS yields to fall at least as much as debt yields.

We note that the agency debt and mortgage-backed securities markets are predicated on the Congressional charter. That charter provides access to the market, opens up classes of investors to agency securities, provides stability to investors and lowers the yields of both agency debt and of MBS, thus fostering the 30-year mortgage.

Keywords: Fannie Mae, Freddie Mac, GSE, subsidy, efficient markets, agency debt, mortgage backed security, MBS

JEL Classification: D21, D40, D52, E44, G10, G21, L11

Suggested Citation

Fratantoni, Michael and Niculescu, Peter, Subsidies in a Context of Efficient Markets: A New Framework for Evaluating the Role of Fannie Mae (November 2, 2005). Available at SSRN: or

Michael Fratantoni

Washington Mutual ( email )

United States

Foster School of Business, University of Washington ( email )

Box 353200
Seattle, WA 98195-3200
United States

Peter Niculescu (Contact Author)

Fannie Mae ( email )

3900 Wisconsin Avenue, NW
Washington, DC 20016-2892
United States

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