Federal Agency Securities: GSEs, Ginnie Mae, and Agency Debt Explained

Published: April 8, 2026

Article by Ryan O'Connell, CFA, FRM

Federal agency securities are debt obligations issued by government-sponsored enterprises (GSEs) and federally related institutions to fund housing, agriculture, and other policy objectives. These securities offer yields above U.S. Treasuries while maintaining high credit quality, making them a core holding for institutional investors, banks, and central banks worldwide. Understanding the distinction between explicit government backing and implicit guarantees is essential for evaluating agency credit risk and yield spreads.

What Are Federal Agency Securities?

Federal agency securities encompass debt instruments issued by two categories of entities: federally related institutions (government agencies with explicit U.S. government backing) and government-sponsored enterprises (privately owned, publicly chartered corporations with an implied government guarantee).

This distinction matters for pricing: explicitly backed agency securities trade closer to Treasury yields, while GSE debt trades at wider spreads reflecting the (however small) credit risk.

Fannie Mae and Freddie Mac

Fannie Mae (Federal National Mortgage Association) and Freddie Mac (Federal Home Loan Mortgage Corporation) are the two largest GSEs, dominating the secondary mortgage market. Both issue two types of securities:

• Agency debt — Unsecured debentures, notes, and bonds backed by the GSE’s general credit
• Agency MBS — Mortgage-backed securities where the GSE guarantees timely payment of principal and interest

In September 2008, both GSEs were placed into federal conservatorship under the Federal Housing Finance Agency (FHFA). While this stabilized their credit standing, the long-term resolution of conservatorship remains unresolved, creating ongoing uncertainty about their government relationship.

Ginnie Mae

Ginnie Mae (Government National Mortgage Association) is the only major housing-related issuer that carries the full faith and credit of the U.S. government. Unlike Fannie Mae and Freddie Mac, Ginnie Mae is a federally related institution—a government agency within the Department of Housing and Urban Development.

Ginnie Mae does not issue debt securities directly. Instead, it guarantees mortgage-backed securities backed by government-insured loans (FHA, VA, USDA). This explicit guarantee means Ginnie Mae MBS have effectively zero credit risk and trade at the tightest spreads to Treasuries among agency securities.

Federal Home Loan Banks

The Federal Home Loan Bank (FHLB) System consists of 11 regional banks that provide liquidity to member financial institutions (primarily banks, credit unions, and insurance companies). FHLBs fund themselves through consolidated obligations—debt securities that are the joint and several liability of all 11 banks.

Key FHLB debt instruments include:

FHLB interest is exempt from state and local income taxes, giving it a tax advantage over Fannie Mae and Freddie Mac debt for investors in high-tax states.

Other Agency-Sector Issuers

Beyond the major housing GSEs, several other entities issue agency-sector securities:

• Farm Credit System — A GSE network providing agricultural credit. Issues consolidated debt as joint and several obligations through the Federal Farm Credit Banks Funding Corporation.
• Tennessee Valley Authority (TVA) — The nation’s largest public power system. Issues power bonds with high credit ratings (Aaa/AA+), though not explicitly backed by the U.S. government.
• Small Business Administration (SBA) — Issues loan pools and debentures backed by small business loans, with explicit federal backing.
• Farmer Mac — A GSE providing secondary market liquidity for agricultural real estate and rural utility loans.

Farm Credit System interest, like FHLB, is exempt from state and local taxes.

Agency Debt Securities

Agency debt takes several forms depending on maturity and structure:

Agency Debentures

Unsecured bonds with maturities typically ranging from 2 to 30 years. Noncallable debentures (Benchmark Notes, Reference Notes) are the most liquid and serve as pricing benchmarks. Callable debentures give the issuer the right to redeem early, typically after a lockout period (e.g., “5-year non-call 1-year” or “5nc1”).

Discount Notes

Short-term instruments with maturities from overnight to 360 days, sold at a discount to face value with no coupon—mechanically identical to Treasury bills. Major issuers include Fannie Mae, Freddie Mac, and FHLB.

Callable Agency Securities

Callable agencies offer higher yields than bullets to compensate for call risk. When rates fall, issuers refinance at lower rates, calling the existing bonds. Investors face negative convexity—gains are capped when rates decline while losses are uncapped when rates rise.

Typical Guarantee and Credit Hierarchy

Agency securities span a credit spectrum from explicit government backing to implied support:

Spreads vary with maturity, market conditions, and whether the security is callable. During the 2008 financial crisis, Fannie Mae spreads widened to 150 basis points before conservatorship restored confidence.

How to Analyze Agency Spreads

For noncallable agency debt, a simple nominal spread (yield minus Treasury yield of same maturity) captures the credit and liquidity premium.

For callable agency debt, nominal spreads overstate the true premium because they ignore the value of the embedded call option. Use option-adjusted spread (OAS):

1. Model interest rate paths using a term structure model
2. Project cash flows under each path, accounting for call exercise
3. Find the constant spread that equates the average present value to the market price

A callable agency trading at 99 bps nominal spread might have an OAS of only 80 bps once the call option value (19 bps) is stripped out. OAS allows apples-to-apples comparison with bullet securities.

Agency Spread Example

Understanding credit risk and default probability helps contextualize why agency spreads differ across issuers despite similar structures.

GSE Debt vs. GSE MBS

GSEs like Fannie Mae and Freddie Mac issue both unsecured debt and mortgage-backed securities. These serve different purposes and have distinct risk profiles:

GSE debt is simpler to analyze—credit risk is the primary consideration. GSE MBS requires sophisticated prepayment modeling, making it more complex but often offering higher yields.

Limitations

• Conservatorship uncertainty: Fannie Mae and Freddie Mac have been in conservatorship since 2008 with no clear resolution path. Legislative reform could change their government relationship.
• Interest rate sensitivity: Agency securities, especially long-duration and callable issues, are sensitive to rate changes.
• Liquidity variation: Benchmark issues are highly liquid; off-the-run and structured agency debt may trade with wider bid-ask spreads.
• Call risk: Callable agencies underperform in falling-rate environments when issuers exercise their call options.

Common Mistakes

1. Assuming all agency securities have government backing. Only Ginnie Mae and certain federally related institutions carry explicit full faith and credit guarantees. Fannie Mae, Freddie Mac, FHLB, and Farm Credit do not.
2. Confusing agency debt with agency MBS. Agency debt is an unsecured obligation of the issuer; agency MBS is a security backed by mortgage pools with a GSE guarantee. The risk profiles differ significantly.
3. Ignoring call risk on callable agencies. Using nominal spread instead of OAS overstates the true yield premium and understates risk.
4. Treating GSE spreads as static. Agency spreads widened dramatically during the 2008 crisis and can move with market stress, regulatory changes, or GSE-specific events.
5. Overlooking tax treatment. FHLB and Farm Credit interest is state/local tax-exempt; Fannie Mae and Freddie Mac is not. This affects after-tax returns for investors in high-tax states.

Frequently Asked Questions