Bill Ackman's Pershing Square takes new Microsoft stake, citing underpriced AI value and OpenAI upside

Ackman's Microsoft Bet Hinges on AI Optionality and Enterprise Durability

Bill Ackman's Pershing Square is building a position in Microsoft, betting that Wall Street has mispriced both the company's AI upside and the resilience of its core business. Microsoft shares are down 15% year-to-date and have shed more than a quarter of their value since their peak last fall, part of a broader software sell-off driven by investor anxiety over AI capex spending.

Ackman's thesis centers on two underappreciated assets. First, the durability of Microsoft 365 subscriptions across enterprise customers, which he argues are far more sticky than the market currently prices in. The embedded nature of the Office suite and its "highly attractive price value proposition" suggest deeper resilience than recent selloffs reflect. Second, Microsoft's 27% stake in OpenAI—valued at approximately $200 billion—which Ackman contends Wall Street hasn't adequately factored into the stock's valuation.

The timing is notable. Ackman is disclosing the stake in regulatory filings, and the move follows a pattern: he deployed similar playbooks with Meta (betting on capex guidance response) and Google (positioned around ChatGPT disruption concerns). The strategy amounts to buying into mega-cap tech names after sharp drawdowns, betting that market pessimism has overshot.

The Microsoft-OpenAI partnership represents the harder-to-quantify but potentially larger prize. As OpenAI moves closer to its valuation milestone, any upside in the startup's value flows directly to Microsoft's balance sheet. That optionality—combined with the enterprise subscription moat—positions the bet as a play on both near-term stabilization and longer-term AI monetization.