Did Mortgage Rate Locks Lead to Rising House Prices?

Why It Matters

Understanding mortgage rate‑lock effects helps policymakers and lenders design financing products that temper price spikes, while investors can better gauge housing‑market risk in rising‑rate environments.

Key Takeaways

• Mortgage rate lock slowed homeowner moves during 2021‑2023
• Rate lock contributed roughly one‑third of 24% nominal price rise
• Fixed‑rate mortgages create pre‑payment costs deterring sales
• Lock‑in offsets but does not outweigh higher user‑cost effects
• Adjustable or portable mortgages could curb lock‑in price pressure

Summary

The Joint Center webcast examined whether mortgage rate‑lock incentives helped fuel the sharp rise in U.S. home prices amid the pandemic. As the Fed pushed 30‑year rates from about 2.5% to near 8%, analysts expected a steep price decline, yet existing‑home values kept climbing while sales fell roughly 40%. Researchers Justin Katz and Robert Minton explored how homeowners locked into low‑rate fixed mortgages faced pre‑payment costs that discouraged moving, effectively reducing resale supply and, in some segments, demand.

Using a natural‑experiment design that linked unexpected child‑birth timing to mortgage origination dates, the authors isolated the impact of outstanding mortgage rates on price growth from 2021‑2023. Their estimates indicate that rate‑lock mechanisms explain about a third of the 24% nominal increase in house prices, while the remaining rise stems from broader factors such as remote‑work‑driven demand. Household‑level data showed owners with lower fixed rates were significantly less likely to transition to renting, confirming the lock‑in effect.

The presentation highlighted that even though rate lock raises prices, its positive influence is smaller than the negative user‑cost effect of higher borrowing rates; an overall rise in rates still predicts price declines absent lock‑in. Counterfactual simulations demonstrated that mortgage products allowing rate adjustments or portability would markedly dampen the price boost, suggesting product design as a lever for market stability.

For policymakers, lenders, and investors, the findings underscore that mortgage contract features matter for housing‑market equilibrium. While rate lock is a non‑trivial driver of recent price gains, addressing it through more flexible mortgage terms could mitigate future price volatility and improve housing affordability.

Original Description

While rising interest rates usually have a negative impact on home prices, between 2021 and 2023, when interest rates increased by almost four percentage points, house prices rose 17 percent, relative to rents. Meyer Fellow and PhD candidate Justin Katz will discuss research he did with Robert Minton exploring whether homeowners locked into below-market, fixed-rate mortgages chose not to move to avoid higher borrowing costs, and to what extent this may have contributed to the sharp rise in home prices.