The recent market moves in South Korean stocks have been breathtaking.

South Korea’s central bank raised rates for the first time in three and a half years, and the KOSPI index plunged, triggering a trading halt. SK hynix fell directly by more than 11%, after a series of further declines in U.S. stock ADRs last night.

As interest rates rise and liquidity is tightened, there’s less money in the stock market; stocks in the semiconductor sector—those that had already surged—get sold first. With heavy leverage players in the Korean market in large numbers, once prices drop, it’s easy for them to smash each other’s bids.

Those who have already made enough money earlier choose to first pocket their profits, while those who are trapped are all waiting for the government to step in and provide a backstop.