Bill Ackman has been quietly buying Microsoft since February, when AI fears were dragging the stock

Bill Ackman is going against the grain to back Microsoft.

Pershing Square Capital Management, the hedge fund run by the billionaire investor, has built a new position in the software giant. 

And in typical Ackman fashion, he disclosed the stake in his trademark style: a lengthy post on X on Friday ahead of his firm’s quarterly 13F filing (a required filing for institutional investment managers with over $100 million in assets). He did not disclose the size, but called it a “core holding.”

Pershing started accumulating shares in February, after Microsoft’s stock fell about 10% the day after Q2 earnings, with a 1% lower-than-expected cloud growth along...