Bill Ackman's Pershing Square boosts MSFT stake to 5.65M shares; trims AMZN in Q1 2026 13F

Pershing Square Capital Management, the mega-fund run by activist investor Bill Ackman, filed its first-quarter 2026 Form 13F-HR on May 15, revealing significant portfolio adjustments. The standout move was a new initiation of 5.65 million Microsoft shares, becoming one of the largest positions in the fund. Ackman noted that he had begun purchasing MSFT in February at approximately 21x forward earnings, a valuation he characterized as "in line with the market and cheap relative to its own history." The timing was prescient; MSFT subsequently rallied alongside the AI wave, and Ackman's stake benefited from both the broader tech rally and Microsoft's strong positioning in enterprise AI adoption through its partnership with OpenAI.

In contrast, Pershing Square reduced its Amazon holdings by exiting or trimming the position, despite AMZN's resilience in the mega-cap complex. The divergence suggested that Ackman saw greater upside in MSFT's cloud and AI infrastructure narrative versus Amazon's more diversified but mature retail and cloud business. The 13F also reflected broader portfolio dynamics: value-oriented investors like Ackman were increasingly drawn to mega-cap tech on the thesis that these companies would capture outsized returns from AI capex spending, even as traditional value metrics looked stretched.

The filing came as the broader tech cohort faced headwinds from the bond selloff and inflationThe rate at which prices rise across an economy. concerns. MSFT, like NVDA and other mega-caps, sold off Friday as yields surged, but the strength of Ackman's commitment suggested conviction that the long-term AI narrative would overcome near-term macro noise. Pershing Square's track record of long-term conviction buying into weakness (as it had done in the past with HP Inc. and other names) lent credibility to the MSFT bet.

Sceptics noted that Ackman's purchases in February, at a time of still-strong market momentumThe empirical fact that winners keep winning over the medium term., were not contrarian in timing. Additionally, the reduction in AMZN raised questions about whether Ackman saw Amazon's exposure to retail and logistics as a liability in a potential recession scenario. The portfolio moves ultimately reflected a bullish view on AI infrastructure winners (MSFT, cloud) and a cautious stance on mega-cap retail (AMZN), a positioning that would be tested by earnings and macro stability in the coming weeks.