Billionaire Bill Ackman has become one of the most closely followed investors in the modern era.
His hedge fund, Pershing Square Holdings, typically runs with a concentrated portfolio of 10 to 12 stocks (although sometimes more), in which he and his team conduct in-depth, bottom-up fundamental analysis of individual names trading at attractive valuations relative to their fair value.
Ackman reportedly sees himself as a modern-day Warren Buffett and isn’t afraid to hold stocks for longer time frames. His portfolio currently holds several hyperscalers, so he’s not necessarily worried about artificial intelligence, but he also clearly understands the market’s various cycles, having been through several in his career.
If a stock market crash is coming, Ackman would advise investors to do this one thing right now.
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Ackman thinks like Buffett in market crashes
Investors are certainly getting nervous about a market that’s essentially been on a multi-year bull run, albeit with plenty of volatility. It seems like not a day goes by without some market strategist or TV pundit speculating about an upcoming market crash. Of course, plenty of investors are still quite bullish.
While AI so far appears to be a game-changing technology, other market indicators suggest the market is trading at elevated levels not seen since the dot-com bubble. Whether a market crash plays out or not is anyone’s guess, as predicting near-term events in the stock market is next to impossible.
Similar to Buffett, who advises investors to “be fearful when others are greedy, and greedy when others are fearful,” , Ackman also sees any significant sell-off as an opportunity. “Anytime that something happens in markets that creates uncertainty, generally stocks go down, risk premia go up,” the billionaire said during a fireside chat in 2025. “If you wait until the uncertainty goes away, then everything reprices… [and] is much more likely to go back to fair value.”
Ackman added: “You as an investor should get excited anytime … it gets uncertain, and the clouds come in, the storm is going. That’s when you want to have capital to invest.”
His advice makes plenty of sense for long-term investors. Buying stocks at high valuations when the market is high can still work in the long term. However, it’s even better when you can take advantage of a temporary market disruption to get into a stock trading at a beaten-down valuation, especially if it has more to do with trading activity than the company’s fundamental business.
Since the pandemic’s height, steep market sell-offs have recovered quickly, rewarding investors who had the gumption to buy when fear was high.
Good ways to implement Ackman’s advice
Investors should not conflate Ackman’s advice with just purchasing any stock that sells off. Often, the sell-offs occur for good reasons. It’s more about finding stocks whose business model and long-term investment thesis remain intact when the stock is being sold. In fact, Pershing runs a great model for knowing when to buy stocks trading at low valuations.
Pershing’s Chief Investment Officer, Ryan Israel, explained how Pershing decides which stocks to pull the trigger on during a sell-off, and how it used this approach to buy Amazon after the stock struggled in the second quarter of 2025 following President Donald Trump’s big tariff surprise. During an investor update last year, Israel said:
… We follow a collection of hundreds of businesses that we have not really owned or haven’t owned in a long period of time that we think are first-rate businesses that we would love to own when we think the price is right and we think the returns meet the threshold that we’re looking for, and Amazon has been on that list for many years.
So, if you have a watch list you monitor over time and actually get to know those businesses, you will have an easier time deciding what to buy during sell-offs. Remember, timing the market is next to impossible, so you’ll never know exactly when a sell-off is coming. That’s why always having at least a small separate pool of cash ready, if possible, is a good idea.
