The Pandemic Housing Boom unleashed an “investor mania” unlike anything seen in the U.S. housing market since the aughts housing bubble. Average Joes poured into the market in hopes of building Airbnb empires. Institutional investors, like Blackstone-owned Home Partners of America, quickly expanded their single-family home portfolios. Homebuilders, eager to strike while the irons were hot, broke ground on a record number of “spec” homes. While iBuyers, like Opendoor and Zillow, ramped up their algorithmic homebuying programs.

Fast-forward to October, and that investor mania has been replaced by investor panic. The ongoing housing correction—U.S. home prices have fallen 1.6% between June and August—has scared many investors to the sidelines. That marks the first national home price decline since 2012.

The investor pullback makes sense. While most housing economists don’t foresee a correction on scale with the Great Financial Crisis bust—during which U.S. home prices fell 27% between 2006 and 2012—they do acknowledge that this home price correction is sharper than it was in 2006. The lagged Case-Shiller Index already shows that home prices are down 8.2% in San Francisco.

To Redfin CEO Glenn Kelman, the Pandemic Housing Boom’s investor frenzy helps explain why home prices are correcting faster this time around. Historically speaking, home prices are sticky. Sellers simply don’t want to relent on price unless economics, like a supply glut, force their hand. That’s not as much the case for institutional investors and builders. If they think prices are about to drop, they want to get out first. The fact that the Pandemic Housing Boom saw investors become a higher share of buyers, Kelman says, ultimately makes the U.S. housing market more vulnerable to a faster swing down.

“When the shiitake mushrooms hit the fan, you [investors] want to get out first. The way to do that is to figure out where the lowest sale is, and be 2% below that. And if it doesn’t sell in the first weekend, move it down [again],” Kelman says.