Bill Ackman discloses a stake in Microsoft through Pershing Square.

Here is what Ackman said on X:

"We believe Microsoft's recent share price decline has been principally driven by investor concerns around two key issues: i) the competitive positioning of M365 against increasingly capable AI lab offerings (notably Anthropic's Claude Cowork), and ii) the durability of Azure's growth, especially in light of Microsoft's evolving relationship with OpenAI.

In our view, investors underestimate the resilience of the M365 franchise given its deeply embedded role across enterprises and highly attractive price-value proposition."

This follows on recent stakes in Amazon and Google.