Though earnings season is the quarterly pinnacle for most investors, the filing of Form 13Fs can be just as telling. This required quarterly filing allows investors to track which stocks Wall Street's savviest money managers have been buying and selling, including Pershing Square's (PS +3.78%) billionaire boss, Bill Ackman.
The latest round of 13Fs, detailing first-quarter trading activity, shows that Ackman purchased shares of Amazon (AMZN -0.14%) and Microsoft (MSFT +2.54%) hand over fist, while at the same time slashing one of his fund's largest positions, Alphabet (GOOGL -1.29%)(GOOG -0.97%), by 95%.
Image source: Getty Images.
Pershing Square Capital Management's billionaire boss piled into two "magnificent" stocks
As an activist investor, Ackman tends to oversee a concentrated portfolio of around one dozen stocks. During the March-ended quarter, he nabbed 5,654,078 shares of Microsoft, making it his fund's fourth-largest position, and scooped up an additional 1,844,157 shares of Amazon, which is now Pershing Square's No. 2 holding by market value.
Ackman laid out his reasoning for piling into Microsoft ahead of his company's 13F filing, noting:
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.
NASDAQ: MSFT
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Ackman is known to take advantage of price dislocations when short-term fears unduly weigh on market leaders. The rout of software stocks in February, coupled with questions about Microsoft's Azure cloud platform, opened the door for Ackman to pounce.
It's a similar story with Amazon, which was underperforming other members of the "Magnificent Seven" when Pershing Square's lead investor began scooping up shares in the second quarter of 2025. Since Ackman's initial purchase, we've witnessed the integration of generative AI solutions and large language model capabilities reaccelerate sales growth for Amazon Web Services -- Amazon's highest-margin segment.
Image source: Getty Images.
Billionaire Bill Ackman nearly cut the cord on Google parent Alphabet
At the other end of the spectrum, Ackman virtually kicked the hottest member of the Magnificent Seven to the curb. He oversaw the sale of 5,852,145 Class A shares of Alphabet (GOOGL) and 645,921 Class C shares (GOOG). Both positions were reduced by 95% from where they stood on Dec. 31.
Despite this aggressive selling, Pershing Square Capital Management's chief investor made clear in a post on social media platform X that he remains optimistic about Alphabet over the long run. But when presented with the opportunity to pile into Microsoft at a historically attractive valuation, and possessing a finite amount of cash, selling Alphabet stock at a healthy profit was the solution.
To be clear, our sale of $GOOG was not a bet against the company. We are very bullish long term on Alphabet. But at current valuations and in light of our finite capital base, we used $GOOG as a source of funds for $MSFT. https://t.co/0ePZI8p3Bh
-- Bill Ackman (@BillAckman) May 16, 2026
The argument can certainly be made that Alphabet isn't the bargain it was at this time last year. Investors were able to snag shares at less than 17 times forward-year earnings. As of this writing on May 17, Alphabet is trading at a forward price-to-earnings ratio of nearly 28.
However, Alphabet is also increasing sales in its highest-margin segment at a considerably faster pace than it was a year ago. Integrating AI solutions into Google Cloud sent sales at the world's No. 3 cloud infrastructure service platform skyrocketing 63% in the first quarter. Alphabet is turning into an AI kingpin before our eyes.
