Bill Ackman's fund Pershing Square shared their strategy for market downturns. Ackman says market uncertainty is the best time to buy before stocks reprice to fair value. Their CIO noted they keep a running watch list of quality businesses they want to own, which is exactly how they bought Amazon during a recent tariff-related sell-off. The main takeaway is to keep some cash ready and know which companies you actually want to buy before the broader market takes a hit.