Bill Ackman, founder and CEO of Pershing Square Inc., attends his company’s IPO at the New York Stock Exchange (NYSE), in New York City, U.S., April 29, 2026. Brendan McDermid | Reuters Bill Ackman's Pershing Square has built a position in Microsoft , the billionaire hedge fund manager said Friday in a post on X . "As two of the largest forces in equity markets -- growing index ownership and increasing amounts of capital controlled by extremely short-term-oriented, leveraged, volatility-intolerant investors -- converge, we have found occasional opportunities to acquire some of the most dominant long-term compounding franchises at attractive valuations," the post said.…