agency mortgage-backed security

agency mortgage-backed security
Name	Agency mortgage-backed security
Type	Mortgage-backed security
Issuer	Federal National Mortgage Association; Federal Home Loan Mortgage Corporation; Government National Mortgage Association
Asset class	Fixed-income security
Currency	United States dollar
Introduced	1970s
Legal structure	Pass-through; principal-only; interest-only; collateralized

agency mortgage-backed security

An agency mortgage-backed security is a securitized Fixed-income security issued or guaranteed by a federally related agency or government-sponsored enterprise such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or the Government National Mortgage Association. These instruments pool residential mortgage loans originated by depository institutions such as JPMorgan Chase, Bank of America, Wells Fargo and nonbank lenders such as Quicken Loans to create tradable claims with pass-through cash flows, principal prepayment features, and credit support mechanisms used by investors including Pension Benefit Guaranty Corporation, BlackRock, Vanguard Group and sovereign wealth funds like the Government Pension Fund of Norway.

Overview

Agency mortgage-backed securities serve as a conduit between mortgage originators and capital market investors including Goldman Sachs, Morgan Stanley, Citigroup, and Deutsche Bank. By converting pools of mortgage loans into securitized tranches, these instruments facilitate funding for primary market activities by originators such as Countrywide Financial (historical) and contemporaries like Rocket Mortgage. The presence of explicit or implied guarantees from entities such as the Government National Mortgage Association or the conservatorship‑era Federal Housing Finance Agency enhances market liquidity and shapes benchmark yields against instruments like Treasury notes and Agency bonds.

Structure and Types

Agency MBS structures include pass-through certificates issued directly by Government National Mortgage Association and structured pools issued by Federal National Mortgage Association and Federal Home Loan Mortgage Corporation. Standard forms comprise 30-year and 15-year fixed-rate mortgage pools originated by banks like PNC Financial Services and regional lenders such as SunTrust Banks (now Truist Financial). Variants include collateralized mortgage obligations used by BlackRock and principal-only and interest-only strips often traded by hedge funds such as Bridgewater Associates. Mortgage pools are organized by underwriting characteristics originating from entities like Fannie Mae and Freddie Mac and may be re-securitized into structured products that resemble Collateralized debt obligation tranches.

Issuance and Market Participants

Issuance channels involve originators, aggregators, issuers, and dealers such as Wells Fargo Securities and JPMorgan Securities. Primary issuance often flows through underwriting syndicates including Morgan Stanley and distribution networks using custodian banks like Bank of New York Mellon. Investors range from insurance companies such as MetLife, mutual fund complexes like Fidelity Investments, to central banks including the Federal Reserve Bank of New York which buys agency MBS in open market operations. Secondary market liquidity is supported by broker-dealers in interdealer platforms, market makers such as Cantor Fitzgerald, and clearinghouses overseen by regulators including the Securities and Exchange Commission.

Pricing and Valuation

Valuation relies on discounted cash flow models that incorporate assumptions derived from historical data supplied by entities such as Mortgage Bankers Association and loan-level datasets held by CoreLogic. Key inputs include coupon rates relative to Treasury yield curve, prepayment speeds measured in CPR influenced by refinancing incentives tied to market rates set by Federal Reserve System policy, and conditional default rates. Traders at institutions like Goldman Sachs use option-adjusted spread analysis and Monte Carlo simulation taking into account cash flow uncertainty similar to valuation methods for Interest rate swaps and Callable bonds. Pricing benchmarks often reference the 30-year fixed-rate mortgage and indices produced by Freddie Mac.

Risks and Regulatory Framework

Principal risks include interest rate risk, extension and contraction risk from prepayments, credit risk mitigated by explicit guarantee arrangements from Government National Mortgage Association, and operational risk associated with servicers such as Wells Fargo Home Mortgage. Regulatory oversight involves agencies like the Federal Housing Finance Agency, the Securities and Exchange Commission, and post-crisis reforms enacted under statutes like the Dodd–Frank Wall Street Reform and Consumer Protection Act. Capital and liquidity standards for bank and nonbank holders are influenced by rules promulgated by the Board of Governors of the Federal Reserve System and international accords such as Basel III.

Historical Performance and Market Events

Agency MBS markets experienced rapid growth in the 1980s and 1990s with participation from investment banks such as Lehman Brothers and deterioration during the 2007–2008 financial crisis, which involved the collapse of mortgage originators like IndyMac Bank and interventions by the United States Department of the Treasury. During the crisis, the Federal Reserve implemented large-scale purchases of agency MBS as part of quantitative easing, stabilizing spreads and liquidity. Subsequent episodes include volatility during the COVID-19 pandemic when central bank purchases by the Federal Reserve Bank of New York restored functioning to markets alongside fiscal responses from the United States Congress.

Role in Monetary Policy and Financial Stability

Agency MBS are instruments of monetary transmission used by the Federal Reserve through balance-sheet policy and open market operations targeting mortgage rates and housing finance conditions. Purchases of agency MBS by the Federal Reserve Bank of New York aim to lower mortgage yields, complementing policy rate decisions by the Board of Governors of the Federal Reserve System. Because agencies like Fannie Mae and Freddie Mac are central to credit intermediation for housing, stress in agency MBS markets can have systemic implications involving entities such as major banks and insurers, prompting coordinated regulatory and fiscal responses from bodies like the United States Department of the Treasury and the Financial Stability Oversight Council.

Category:Mortgage-backed security