Bill Ackman discloses new $2.09 billion stake in megacap tech stock

Bill Ackman posted on X on May 15 that Pershing Square had taken a new position and that the 13F filing due later that day would reveal the details. He described the company as sitting at a "highly compelling valuation." He said he started buying in February.

When the filing landed, the position was worth approximately $2.09 billion at the end of the first quarter. And the reasoning Ackman laid out for why he bought it is more specific than most hedge fund disclosures tend to be.

What Ackman bought and the exact terms he used to describe it

Pershing Square Capital Management disclosed ownership of approximately 5.65 million shares of Microsoft in its Q1 2026 13F filing. The stake was valued at approximately $2.09 billion at the end of Q1 and had risen to approximately $2.3 billion by the end of trading on May 15, CNBC confirmed.

Ackman began accumulating shares in February, after Microsoft's stock fell following its fiscal second-quarter earnings report. His exact explanation for the entry point: "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 on X.

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That valuation framing is the core of the thesis. Microsoft trading at 21 times forward earnings placed it roughly in line with the broader market, an unusual position for one of the most dominant software franchises in the world. Ackman's argument is that the market mispriced the stock by focusing on near-term spending concerns rather than the long-term earnings trajectory of the underlying business.

Why Ackman sees Azure and M365 Copilot as the two pillars of the investment case

Ackman described Microsoft's investment thesis around two specific product lines. The first is Azure, Microsoft's cloud computing platform, which he said has benefited from enterprises shifting computing workloads online, a trend now accelerating further as AI integrates into corporate workflows. The second is Microsoft 365, which he described as deeply embedded in corporate workflows in ways that are hard for competitors to replicate.

He specifically called out Copilot, the AI assistant Microsoft has embedded across its products at $30 per user per month, and Azure Foundry, which allows developers to build applications using AI models through Azure's cloud infrastructure. The heavy capital spending tied to AI, he argued, is a necessary investment that could generate substantial future revenue growth, rather than a sign of undisciplined spending.

Ackman also said the market has not yet fully credited Microsoft for its stake in OpenAI, which he sees as additional embedded value that the stock price does not fully reflect, according to 24/7 Wall St.

How the Microsoft bet fits Ackman's pattern on AI-linked tech

Ackman drew an explicit parallel between the Microsoft purchase and earlier Pershing Square bets on Alphabet, Amazon, and Meta during periods when those stocks were facing skepticism about their AI strategies. In each case, the thesis was the same: the market had become too focused on near-term spending and not sufficiently confident in the long-term earnings power of businesses with dominant competitive positions.

The Microsoft position was not the only significant portfolio change in the Q1 filing. Pershing Square exited its Hilton Hotels position entirely and sharply reduced its Alphabet stake. That rotation from Hilton and Alphabet into Microsoft suggests a deliberate repositioning toward what Ackman sees as a more compelling long-term AI infrastructure bet.

Ackman also noted that Microsoft has become a core holding in Pershing Square USA, his new closed-end fund that debuted on the New York Stock Exchange last month. That means the Microsoft thesis is now embedded in two separate Ackman vehicles simultaneously, a sign of conviction that goes beyond a tactical trade, according to GuruFocus.

Key figures from Pershing Square's Q1 2026 Microsoft disclosure:

• Shares purchased: approximately 5.65 million Microsoft shares, disclosed in Q1 2026 13F filing on May 15, according to CNBC
• Position value at end of Q1: approximately $2.09 billion; risen to approximately $2.3 billion by May 15 close, CNBC confirmed
• Entry valuation: 21 times forward earnings, described by Ackman as "broadly in line with the market multiple," CNBC noted
• Buying started: February 2026, following Microsoft's post-earnings selloff after fiscal Q2 results, according to Barron's
• Key thesis elements: Azure cloud growth, M365 Copilot at $30/user/month, Azure Foundry, OpenAI stake not fully valued, Barron's confirmed
• Other Q1 changes: Pershing Square exited Hilton entirely and sharply reduced its Alphabet stake, Barron's noted
• New fund: Microsoft also a core holding in Pershing Square USA, Ackman's closed-end fund that debuted on NYSE last month, according to GuruFocus

What Ackman's Microsoft stake means for investors watching the stock

Microsoft shares rose in early trading on May 15 following the disclosure. That immediate reaction reflects what happens when a well-known value-oriented investor with a track record of concentrated bets publicly validates a stock that has been under pressure. But the more important read is what the thesis says about where Ackman thinks Microsoft is in its cycle.

A 21 times forward earnings entry point on Microsoft is not a bet on an early-stage company. It is a bet that a dominant, deeply entrenched enterprise software and cloud franchise has been mispriced by a market too focused on the cost of AI investment rather than the eventual revenue it is building. Ackman's comparison to his Alphabet, Amazon, and Meta trades during similar periods of skepticism suggests he sees this as a repeatable pattern, not an isolated observation.

Whether the thesis plays out depends primarily on two variables: whether Azure continues to take cloud market share as enterprises accelerate AI adoption, and whether M365 Copilot achieves the kind of per-seat monetization at $30 per month that would justify the AI infrastructure spending Microsoft has committed to. Both questions will be partially answered in every subsequent earnings report. Ackman has signaled he is willing to wait for those answers, with approximately $2 billion of capital on the table.

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This story was originally published May 16, 2026 at 4:17 PM.