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 alongside a surge in capital spending. “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 in the post.

Microsoft’s stock is down more than 15% year-to-date as it fights to prove that its Azure cloud business has enough revenue to justify its AI spending. The erosion of its partnership with AI, which was recently restructured to strip Microsoft of exclusive distribution rights, only furthered those concerns.