For months, the U.S. housing market has been plagued by a historically low inventory of homes for sale, which has increased competition and driven prices to record highs.

The housing market finally appears to be entering a cool-off period, with prices beginning to decelerate. But the number of homes for sale is still low, and two new housing reports suggest that the very measure that is cooling down the housing market right now might be what is keeping inventory from bouncing back.

Home prices have gained 19.2% over the past 12 months, a surge that has locked many potential homebuyers out of the market.

Two factors collided over the past few years to send prices this high. Demand for housing increased amid the early-pandemic low mortgage rates while the supply of new homes sat at historic lows, creating the perfect recipe for intense competition and higher prices.

But now that relationship is breaking down too, and the calculus is changing.

Homeowners don’t want to leave

Why sell a house with a mortgage attached at a rate between 2% to 3%, and buy a new one with a mortgage rate around 5%? That’s the question the market is posing to potential sellers now.

Maybe it shouldn’t be a surprise they don’t want to sell.

Competition for housing is beginning to cool as demand has died down amid a record-high surge in mortgage rates in the first months of 2022.

The surge in demand for new housing over the past two years must have been fueled in part by then-low mortgage rates after the Federal Reserve lowered rates in response to the pandemic. The average 30-year fixed mortgage rate in 2021 was 2.96%, with the metric hitting an all-time low in January 2021 when mortgages sat at 2.65%.

Buying a home back then and nailing down a record-low mortgage was a no-brainer for many prospective homebuyers, despite the rising home prices. But if 2020 and 2021 were the best years to buy a home with a mortgage, 2022 is the polar opposite.

As of April 2022, 30-year fixed mortgages are sitting well above 5%, after the Federal Reserve began raising interest rates to combat inflation. For homeowners who already nabbed extremely comfortable rates earlier in the pandemic, the thought of putting their home on the market now might not be very appealing if it means buying a new home that locks them into a high rate.

More than half of current homeowners were able to lock in a fixed rate below 4%, according to a new report by online real estate site Redfin. An unwillingness to move and take on a higher mortgage may be what has already led to a 7% drop in new listings this spring relative to last year.

If you own a home right now, it is probably worth the cost, according to the latest national housing survey by Fannie Mae, a government-sponsored mortgage financing agency. The survey found that 92% of current homeowners, regardless of income level, believe that their home is either somewhat or very affordable.

Low mortgage rates used to be the buffer that justified a home purchase even when home prices were high. That buffer is now gone, as most current homeowners are enjoying fixed rates far below what they would have to deal with should they decide to move.

Nobody wants a higher mortgage

Homeowners are holding on to their homes for longer because moving and finding a new home in the current market is too expensive. From a personal finance standpoint, the decision is probably wise. But from a macro perspective on the U.S. housing economy, it’s bad news.

Higher mortgage rates and lower demand for homes is helping to cool the housing market, but increasing inventory is critical. More listings and more homes on the market would have the biggest effect on alleviating competition, giving buyers more negotiating power, and reining in prices.

In a promising sign, new-construction starts for homes in the U.S. are growing at a steady rate, but until current homeowners begin to venture back into the market, supply will remain constrained, and prices will likely stay relatively high.