Ackman Quietly Bought Microsoft at 21x — The Logic Behind a $2.09 Billion Bet

Bill Ackman bought $2.09 billion of Microsoft at a forward P/E of 21x. He sold all of Hilton and sharply cut Alphabet.

Bill Ackman posted a simple note on X on May 15: "Today's 13F contains a new position. We bought at an attractive valuation." When the filing dropped, the position stood at roughly $2.09 billion. By the close on May 15, it had grown to approximately $2.3 billion.

The stock was Microsoft (MSFT).

He Bought During the February Earnings Shock — "At the Same Multiple as the Market"

Ackman was specific about his entry thesis:

"We built the position at a forward P/E of 21x — in line with the overall market multiple and well below Microsoft's average multiple over the past several years."

Bill Ackman, Pershing Square — X, May 15

A 21x forward P/E is low by Microsoft historical standards. Pershing Square began buying in February when the stock pulled back after Microsoft's fiscal Q2 earnings. The market focused on near-term AI investment costs; Ackman focused on the long-term revenue trajectory.

Two Core Arguments — Azure and M365 Copilot

Two products form the backbone of this bet:

• Azure: Corporate migration of compute workloads to the cloud is accelerating with AI integration. Azure is the primary infrastructure beneficiary.
• Microsoft 365 Copilot at $30/month: Pure incremental revenue on top of an existing base of hundreds of millions of enterprise M365 users. Mass conversion would structurally upgrade Microsoft's earnings model.
• Azure Foundry: A platform for building AI-model-based applications — AI spend as future revenue, not just cost.
• OpenAI stake: Ackman believes the market has not fully priced in Microsoft's OpenAI equity stake.

The $30/month Copilot subscription converting at scale is the single most important variable in this bet.

Hilton Sold Entirely, Alphabet Cut — A Portfolio Pivot

Alongside the Microsoft purchase, Pershing Square fully exited its Hilton (HLT) position and sharply reduced Alphabet. This is not a simple stock swap. It is a deliberate reallocation from cyclical travel and hospitality into AI infrastructure.

Ackman drew an explicit parallel to previous bets on Alphabet, Amazon, and Meta — all entered when market skepticism about their AI strategies peaked, then held through to long-term earnings realization.

Microsoft is also a core holding in the Pershing Square USA closed-end fund, which recently listed on the NYSE. Two separate Ackman investment vehicles holding the same name simultaneously signals a long-term conviction position, not a trade.

Two Numbers Will Validate the Thesis

Whether this bet proves right comes down to two data points: whether Azure continues to take cloud market share, and whether M365 Copilot subscriptions convert at scale. Both questions get partially answered every quarter. Ackman has put roughly $2.09 billion on the table to wait for those answers.