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 , as the hedge fund manager said the software giant's recent pullback created a rare opportunity to buy one of the world's dominant technology franchises at a compelling valuation. Ackman disclosed the investment in a lengthy post Friday ahead of his firm's quarterly 13F filing, saying Pershing Square began accumulating shares in February after Microsoft's stock declined following its fiscal second-quarter earnings report. "We were able to establish our position at a valuation of 21 times forward earnings, broadly in line with the market multiple and well below Microsoft's trading average over the last few years," Ackman wrote.…