Why Owners Stay Put
The mechanism is straightforward. A homeowner who locked in a rate below 4% during 2020 or 2021 faces a simple calculation when contemplating a move. The next mortgage will carry today's rate, and a comparable home financed at that rate can cost hundreds of dollars more per month even at the same price. For most owners, the answer is to not move at all. The Federal Reserve Bank of Philadelphia documented this behavior in detail in its 2024 study, When Mortgage Lock-In Locks Out Homebuyers.[2]
Outstanding Mortgages by Interest Rate
A majority of mortgaged homeowners carry a rate below 4%, a level well beneath today's market
Source: Federal Housing Finance Agency[1]. Bars are illustrative of the majority/minority split reported by FHFA, not precise percentages.
A Market Frozen to 1990s Levels
The effect became visible the moment financing costs jumped. When the 30-year mortgage rate rose above 6% in September 2022, the annualized pace of existing-home sales fell below 4.5 million.[3] That is a pace last seen in the mid-1990s, when the U.S. population was roughly 22% smaller than it is today.[2] The same volume of transactions is now spread across a far larger nation, which means the freeze is deeper per household than the raw figure suggests.
| The Freeze in Context | Figure | Note |
|---|---|---|
| 30-year rate crosses 6% | Sept. 2022 | Trigger point |
| Annualized existing-home sales | Below 4.5M | After the crossing |
| Last time at this pace | Mid-1990s | Roughly 30 years earlier |
| U.S. population then vs. now | ~22% smaller | Same sales pace, far fewer people |
Sources: National Association of Realtors[3]; Federal Reserve Bank of Philadelphia[2]
The Supply the Market Was Counting On
Existing homes normally supply the vast majority of listings each year. When a majority of owners are financially locked in place, that pipeline narrows regardless of demand. FHFA estimates the resulting supply reduction pushed home prices up roughly 7%.[1] Lower rates might eventually unlock some of it, but that is a forecast, not a plan.
Construction Is the Only Release Valve
The lock-in effect exposes a structural weakness in relying on the existing housing stock to relieve prices. Owners respond to their own financial incentives, not to buyers' needs. When those incentives say stay, the resale market contracts and no policy lever can compel millions of households to list their homes.
This leaves one dependable source of new inventory: building more homes. New construction adds to supply without requiring any existing owner to give up a favorable rate. Even if rates fall and some lock-in unwinds, a market this dependent on the choices of sub-4% borrowers has shown it cannot be counted on. The prudent response is to expand the supply the country actually controls.
Policy Connection
The rate lock-in effect is the clearest case for the Affordability and Immigration Act's fifth proposal. When existing supply is frozen, only new supply can move the market.
- -Policy 5 increases housing construction through federal-local partnerships, rewarding jurisdictions that exceed production targets and streamlining permitting so new homes reach the market faster.
- -Because it adds inventory directly, new construction relieves prices without depending on locked-in owners choosing to sell, a choice policy cannot force.
- -The 1.7 million missing sales are a warning: a housing strategy that assumes existing owners will supply the market is a strategy built on an assumption the data no longer supports.
Sources
- Federal Housing Finance Agency: Research on the Mortgage Rate Lock-In Effect - Share of mortgages below 4%, roughly 1.7 million fewer sales (2022-2024), and the approximately 7% price effect (Jonah Coste)
- Federal Reserve Bank of Philadelphia: When Mortgage Lock-In Locks Out Homebuyers (Economic Insights, 2024 Q2) - Documentation of the lock-in mechanism and the mid-1990s sales-pace comparison
- National Association of Realtors: Existing-Home Sales - Annualized existing-home sales falling below 4.5 million after rates crossed 6% in September 2022