Hedge-fund manager Bill Ackman likes Mark Zuckerberg's chances in the artificial-intelligence race.

Ackman's Pershing Square revealed a new stake in Meta Platforms at the annual meeting of one of its funds on Wednesday. The position amounted to 10% of the firm's capital at the end of 2025, or roughly $2 billion based on past disclosures.

Meta shares are down about 13% over the past six months, a decline that Pershing Square attributes to investor concerns about the sums the company is spending on AI initiatives. Pershing Square's thesis revolves in part around AI boosting Meta's content recommendations and personalized ads and potentially unlocking new opportunities in wearables or AI digital assistants for businesses.

"Meta's business model is one of the clearest beneficiaries of AI integration," Pershing Square said in its presentation.

Ackman tends to concentrate his stock portfolio in a small number of high-conviction bets. Pershing Square held only 13 different positions at the end of 2025, including other big tech companies Alphabet and Amazon. In recent months, it sold out of two longtime holdings, Chipotle Mexican Grill and Hilton Worldwide.

Pershing Square Holdings, Ackman's main stock-picking fund, gained 20.9% in 2025, outpacing the S&P 500's total return of 17.9%. Stakes in Alphabet, Fannie Mae and Freddie Mac were its top contributors. In the first month of 2026, Pershing Square Holdings lost 2.5%.

The firm initiated its bet on Meta in November at an average cost of $625 per share, according to an investor presentation. Meta's stock gained 11% from that date through the end of 2025 and an additional 3% this year through Feb. 9. It closed at $669 on Wednesday.

Other big bets that Pershing Square made in 2025 include a $900 million investment in real-estate company Howard Hughes Holdings and an up to $1 billion backstop for Howard Hughes's acquisition of insurer Vantage Group Holdings. Ackman, a devotee of Warren Buffett, aspires to turn Howard Hughes into a diversified holding company like Berkshire Hathaway.

News of Buffett investing in a company often serves as a catalyst for its stock. In the case of Ackman and Meta, its shares were roughly flat on Wednesday after Pershing Square unveiled its stake. By contrast, disclosure of Pershing Square's roughly 4% stake in rental-car company Hertz last April helped push its share price up by over 50%.