Markets experienced one of the most violent reversals of the artificial-intelligence cycle during the past week, but the most important development was not the fall itself. It was what happened next.

South Korea’s technology-heavy share market rose almost 18% on Friday after having fallen as much as 39% from its June high. Samsung gained approximately 20%, while SK Hynix rose by more than 25% during the session. Semiconductor stocks rebounded sharply in the United States, and several of the companies caught in the earlier sell-off recovered fro...