The Housing and Urban Development Act of 1968 created the Government National Mortgage Association (Ginnie Mae) within HUD and split it from the old, government-owned Fannie Mae. This reshaped federal housing finance by separating a government guarantee function (Ginnie Mae) from other secondary-market activities. It set the stage for a new kind of bond-like product backed by home mortgages.
In early 1970, the first widely cited mortgage-backed security (MBS) tied to Ginnie Mae’s program was brought to market, creating a new way to fund mortgages by selling investors a claim on mortgage payments. This helped lenders replenish cash to make new loans, supporting a larger national mortgage market. It also introduced “prepayment risk,” meaning borrowers can refinance or pay off early, changing investor cash flows.
In 1971, Freddie Mac issued its first mortgage pass-through security, known as a Participation Certificate (PC). Like a pass-through bond, it “passed through” principal and interest from a pool of mortgages to investors. This expanded the agency-style securitization model beyond government-insured loans and helped standardize mortgage funding.
During the 1970s, market participants developed standards that supported a liquid “to-be-announced” (TBA) forward market for agency MBS. In a TBA trade, buyers and sellers agree on general terms (like issuer and coupon) before the exact mortgage pools are identified later. This improved liquidity and made it easier for lenders to hedge interest-rate risk while originating new mortgages.
In 1981, Fannie Mae issued its first mortgage pass-through security, commonly called an MBS. Together with Ginnie Mae and Freddie Mac, this created the core “agency MBS” market—securities issued or guaranteed by housing-related federal entities or government-sponsored enterprises (GSEs). The result was a larger, more integrated national market for conforming mortgages.
In 1983, Freddie Mac supported the first widely recognized collateralized mortgage obligation (CMO), a structured security that divides mortgage cash flows into different “tranches” with different timing rules. This helped attract investors with different maturity and cash-flow needs, but it also increased product complexity. CMOs became a major step toward more engineered mortgage bond markets.
The Secondary Mortgage Market Enhancement Act (SMMEA) of 1984 aimed to reduce regulatory barriers and improve the marketability of non-agency (“private-label”) mortgage-backed securities. It supported broader investor participation by addressing legal and investment limitations that varied across states and institutions. This accelerated growth in securitization outside the traditional agency system.
The Tax Reform Act of 1986 enabled Real Estate Mortgage Investment Conduits (REMICs), a legal-and-tax structure that made it easier to issue multi-tranche mortgage securities without unfavorable tax treatment. This removed key obstacles that early CMOs faced and supported rapid growth in structured mortgage products after 1986. More investors could now buy tailored mortgage-bond tranches with clearer tax rules.
In 1989, the Financial Institutions Reform, Recovery, and Enforcement Act (FIRREA) responded to the savings-and-loan (thrift) crisis by reorganizing supervision and creating the Resolution Trust Corporation (RTC) to resolve failed institutions. Thrifts had been major mortgage lenders, and their failures accelerated changes in how mortgages were funded and sold. The policy shift encouraged a greater role for securitization and capital markets in housing finance.
The Federal Housing Enterprises Financial Safety and Soundness Act of 1992 created the Office of Federal Housing Enterprise Oversight (OFHEO) to supervise the safety and soundness of Fannie Mae and Freddie Mac. It also required HUD to set affordable-housing goals for the enterprises. This law tied the fast-growing agency MBS and agency debt markets more directly to federal oversight and public-policy targets.
The Commodity Futures Modernization Act of 2000 clarified legal treatment for many over-the-counter (OTC) derivatives, contributing to rapid growth in derivatives such as credit default swaps (CDS). In mortgage markets, CDS later became a key tool for taking “synthetic” exposure to mortgage credit risk (gaining or losing value based on mortgage bond performance without owning the bonds). This increased interconnections between mortgage products and the broader financial system.
On April 28, 2004, the SEC voted to allow the largest broker-dealers to seek an alternative net capital approach using internal models to calculate risk “haircuts” on securities positions. In practice, this was associated with higher reliance on complex risk models and, for some firms, the ability to carry larger securities inventories with less capital. This mattered for MBS markets because major dealers were central intermediaries in trading and financing agency and private-label mortgage securities.
In January 2006, CDS IndexCo and Markit launched the ABX.HE index, a tradable set of credit default swaps referencing subprime home-equity-related mortgage bonds. This gave investors and dealers a more standardized way to hedge or bet against subprime mortgage credit performance. The index later played an outsized role in price discovery as subprime conditions worsened.
By 2005, private-label residential mortgage-backed securities (RMBS) issuance reached record levels, reflecting heavy use of securitization for non-agency mortgages such as Alt-A and subprime loans. Ratings agencies reported large and growing volumes of structured mortgage deals, many with numerous bond “classes” (slices with different risk levels). This boom increased the system’s exposure to housing-price declines and mortgage defaults.
In mid-2007, two Bear Stearns hedge funds heavily exposed to subprime mortgage securities suffered major losses and effectively collapsed. The episode helped shift market sentiment by showing that subprime mortgage risk was not contained within a small corner of finance. It contributed to tighter credit conditions and weaker demand for certain mortgage bonds.
The Housing and Economic Recovery Act of 2008 (HERA) created the Federal Housing Finance Agency (FHFA), consolidating and strengthening oversight of Fannie Mae and Freddie Mac. It responded to mounting stress in housing and financial markets, including pressures on the enterprises’ ability to raise capital and issue debt. This marked a major turning point in federal control over the agency MBS and agency debt ecosystem.
On September 6, 2008, FHFA placed Fannie Mae and Freddie Mac into conservatorship to stabilize the firms and the broader housing finance system. This intervention aimed to maintain the flow of mortgage credit and support the functioning of agency debt and agency MBS markets during the financial crisis. It became a defining end-point for the 1970–2008 era of “implied guarantee” assumptions in U.S. agency mortgage finance.
Mortgage-Backed Securities and U.S. Agency Bond Markets, 1970–2008