Q1 13F Season Closes: Tepper Nearly Doubles Amazon, Ackman Goes All-In on Microsoft, Sundheim Dumps Meta

The Filing Deadline Has Passed. Here's What the Data Says.

May 15, 2026 was the SEC deadline for Q1 13F filings, according to HedgeMind's real-time dashboard, which logged 8,525 institutional filings and 1,091 hedge fund filings by end of day.

While much of the coverage has focused on Berkshire's moves last quarter, the broader institutional picture is striking: three of Wall Street's biggest names made coordinated bets on the same sector, and the divergence from headline stocks is significant.

Tepper's Amazon Bet Is the Headline Move

David Tepper's Appaloosa Management nearly doubled its Amazon position — up 98% — making it the fund's largest disclosed equity holding at roughly $900 million as of March 31, according to CNBC. That's a nine-figure conviction call on a stock that dropped more than 9% during Q1.

Tepper didn't stop there. He boosted his Uber stake by 242%, raised Vistra Energy by 114%, and added 18% to Taiwan Semiconductor. He also opened a brand-new $179 million position in Sandisk.

The common thread: AI infrastructure. Semiconductors. Cloud. Power. Tepper is betting that the data center buildout is real and demand will sustain.

He did trim. Alibaba got cut 33%. Nvidia down 13%. Alphabet trimmed 3%. All three stayed in his top 10, suggesting rebalancing rather than abandonment.

Ackman's Microsoft Bet Came Out of Nowhere

Bill Ackman's Pershing Square opened a 100% new position in Microsoft during Q1 — 5,654,078 shares worth $2.09 billion, according to Market Insights Hub's 13F database. Microsoft now represents 15.26% of Pershing Square's entire $13.71 billion portfolio. In one quarter. From zero.

Ackman simultaneously dumped 94.9% of his Alphabet Class C shares and 95.2% of his Alphabet Class A shares. He went from a meaningful Google position to essentially nothing.

He also grew Amazon by 19.2% to $2.39 billion — now his second-largest holding behind Microsoft.

The shift is clean: out of Google, into Microsoft. The apparent logic is that Microsoft's AI integration through Copilot and Azure has stronger positioning than Google's search-plus-AI hybrid model.

Sundheim Torched Meta

Daniel Sundheim's D1 Capital sold its entire Meta position — more than 376,000 shares worth over $240 million — during Q1, according to CNBC. This came after Meta fell more than 13% in the quarter, its third straight quarterly decline and worst performance since 2022.

Sundheim also zeroed out Synopsys and Arista Networks. He trimmed Spotify by 14%.

Simultaneously, he poured money into AI infrastructure plays. Amazon up 34%, now worth $376.5 million in his portfolio. New positions opened in Alphabet, ASML, and Taiwan Semiconductor. Broadcom and Nvidia positions expanded.

Meta has rebounded more than 7% since April 1, meaning Sundheim sold near the bottom. His broader rotation — social media out, AI picks-and-shovels in — reflects a strategic shift rather than panic.

What Mainstream Coverage Is Missing

CNBC covered the Tepper and Sundheim moves on an individual fund basis. But the consensus trade across all three funds deserves attention: Amazon. Tepper at $900M. Ackman at $2.39B. Sundheim adding 34%. Three very different investors with different styles all built positions in the same stock during a quarter when it declined 9%.

Also notable: the 45-day lag problem. 13F filings arrive 45 calendar days after quarter end. These positions reflect where the money was on March 31. Amazon is now up more than 26% since then. The institutional buyers already realized gains while retail investors are reading the headlines.

Ackman's near-total exit from Alphabet deserves more prominence. A 95% dump of Google shares by one of Wall Street's most-watched activists, paired with a $2 billion Microsoft buy, is a significant statement. It's mostly being overlooked.

The Broader Pattern

HedgeMind's dashboard shows $4.4 trillion in total hedge fund equity value reported across 1,091 funds for Q1 2026.

The consensus among the biggest names: AI infrastructure outperforms, social media underperforms, Amazon is the most-favored large-cap bet, and Google is losing investor confidence.

For regular investors: the smartest institutional money bought Amazon on weakness in Q1 and is sitting on double-digit gains. They also exited Meta before it rebounded. Nobody's perfect.

Use 13F data for direction and perspective—not as a trading signal. By the time these filings hit the public, the original trades are already in the past.