Short answer. The rate-lock effect is the freeze in U.S. existing-home listings caused when prevailing mortgage rates rise meaningfully above the rates current owners hold. As of 2024, ~76% of U.S. mortgaged owners hold loans below 5% — making it economically irrational to sell into a 6.8% market.
The rate-lock effect is the central explanation for the 2023–2024 collapse in U.S. existing-home sales to 4.09M and 4.06M — the lowest readings since 1995.
The arithmetic
Consider a household with a $400,000 mortgage at 3% on a $500,000 home. Their monthly principal-and-interest payment is $1,686. If they sell and buy a comparable $500,000 replacement at 7.5%, they're financing $400,000 at 7.5% — a payment of $2,797, a 66% increase for the same loan amount.
Now consider a household trading up. The same $500,000 home becomes a $700,000 home; the mortgage goes from $400K at 3% to $560K at 7.5% — payment from $1,686 to $3,915, up 132%.
Aggregate impact
The Federal Reserve estimates the rate-lock effect has held back roughly 1.5 million U.S. home sales since 2022. Existing-home inventory in 2024 averaged 1.0M units listed nationwide vs a long-term average of 2.5M.
How does it resolve?
Three paths: (1) prevailing rates fall below ~4.5%, making refinancing economic again; (2) life events (job change, divorce, death, downsizing) accumulate and force listings regardless; (3) a recession forces involuntary listings via job-loss-driven foreclosures. Most analysts expect a slow grind via path 2 unless the Fed delivers an aggressive cutting cycle.
Sources
U.S. Census Bureau Survey of Construction; National Association of Realtors Existing Home Sales report; Freddie Mac Primary Mortgage Market Survey; National Bureau of Economic Research Business Cycle Dating Committee.