Bill Ackman's Rough 2026: What a 9% Drawdown Teaches 13F Followers

Bill Ackman has spent the last few years as one of the most-watched names in the 13F universe, and for good reason: Pershing Square's concentrated, low-turnover style makes its filings unusually easy to follow. But 2026 is testing that reputation. Pershing Square's portfolio is down roughly 9.3% this year while the S&P 500 is up 9.6% and the Nasdaq 100 is up 13.4% — a gap of almost 19 percentage points.

For anyone who copies trades out of 13F filings, this is the most instructive story of the summer.

The big Q1 reshuffle

Pershing Square's Q1 2026 13F showed one of Ackman's most aggressive reshuffles in years. The firm initiated a new ~$2.1 billion Microsoft position — instantly its number-four holding at about 15.3% of the roughly $13.7 billion equity book — funded largely by cutting Alphabet exposure by about 95%. Ackman began building the Microsoft stake in February after the stock pulled back, arguing that Azure and Microsoft 365 made the valuation hard to ignore.

He wasn't done. Amazon was increased about 19% to roughly $2.4 billion, while Hilton Worldwide, Chipotle, and Canadian Pacific Kansas City — three long-tenured Pershing names — were exited entirely.

The result is a book of just 11 stocks, with the top five — Brookfield (17.6%), Amazon (17.4%), Uber (15.7%), Microsoft (15.3%), and Restaurant Brands (12.2%) — accounting for nearly 80% of the portfolio. You can track the full position history on his InvestorLens investor page.

Why the portfolio is lagging

Concentration cuts both ways. Brookfield, the top holding, is down about 5.3% since January. Microsoft, the big new bet, has stayed under pressure all year. Amazon is up 6.8% — helpful, but not enough to offset the rest when five names carry most of the weight.

The pain shows up in the listed vehicles too: Pershing Square Inc has slid from an all-time high of $54 to around $34, and UK-listed Pershing Square Holdings is down roughly 25% from its high this year.

None of this means the thesis is wrong. Ackman's holding period is measured in years, and his best trades — Chipotle, Hilton, Universal Music — all endured ugly stretches. But it's a reminder that a 13F tells you what a manager owns, not when the position will work.

Three lessons for 13F followers

Filings are a starting point, not a signal. By the time a 13F drops (45 days after quarter-end), the manager's cost basis, hedges, and any post-quarter trades are invisible. Ackman built Microsoft in February; by the May filing, followers were already buying a different setup. With Q2 filings due August 14, our Q2 13F season preview covers what to watch.

Concentration means tracking error — in both directions. An 11-stock book will never hug the index. The same structure that let Pershing Square crush the market in 2019–2020 is what produces a 19-point shortfall now. If you follow concentrated managers, expect stretches like this and size accordingly.

Watch for confirmation across managers. A single manager's conviction is one data point. When several top investors independently build the same position, the signal is stronger — that's exactly what the overlap tool surfaces. Microsoft and Amazon both show up across multiple tracked portfolios this year; Brookfield is a much lonelier bet.

What to watch in the Q2 filing

Pershing Square's Q2 13F, due by mid-August, will answer the interesting questions: Did Ackman add to Microsoft on weakness, as his history suggests? Did Uber — a crowded billionaire favorite we covered last week — get trimmed after its run? And does the Alphabet stub disappear entirely?

Whatever the answers, the drawdown itself is the lesson. Following great investors means sitting through their bad years, not just harvesting their good ones. You can compare how Ackman's positioning stacks up against the rest of the smart-money universe on our macro consensus page.

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Data sourced from public SEC 13F filings. Educational research only — not investment advice.