Bill Ackman 13F: Pershing Square Q1 2026
Pershing Square reported an 11-position, $13.7B Q1 2026 13F book, with Microsoft new, Amazon added, and Alphabet sharply reduced.
The short version
Bill Ackman's Pershing Square Capital Management reported an 11-position, $13.7 billion U.S. long book for Q1 2026. The effective Form 13F, accepted by the SEC on May 15, 2026, shows Microsoft as a new line, Amazon up 19%, Alphabet cut by roughly 95% across its two share classes, and the six largest positions making up about 89% of reported value.
What did Bill Ackman's latest 13F show?
The latest effective Pershing Square Capital Management filing in Arkolith's 13F corpus is the Q1 2026 Form 13F-HR for the quarter ended March 31, 2026. The filing was accepted by the SEC on May 15, 2026 at 20:19:58 UTC under accession number 0001172661-26-002336. The primary record is the SEC's SEC filing detail page.
The headline is concentration. Pershing Square reported only 11 positive-long 13F lines, or 10 economic positions after combining Alphabet's GOOG and GOOGL classes. Brookfield, Amazon, Uber, Microsoft, Restaurant Brands, and Meta together represented roughly 89% of the reported book. That makes small line-item changes less important than whether the top positions moved.
| Position | Ticker | Reported value | Weight | Q1 change |
|---|---|---|---|---|
| Brookfield Corp. | BN | $2.42B | 17.6% | Reduced 2.8% |
| Amazon | AMZN | $2.39B | 17.4% | Added 19.2% |
| Uber | UBER | $2.15B | 15.7% | Reduced 0.8% |
| Microsoft | MSFT | $2.09B | 15.3% | New line |
| Restaurant Brands | QSR | $1.67B | 12.2% | Reduced 1.0% |
| Meta Platforms | META | $1.52B | 11.1% | Reduced 0.5% |
| Howard Hughes Holdings | HHH | $1.19B | 8.7% | Held |
| Alphabet, both classes | GOOG / GOOGL | $98.7M | 0.7% | Reduced about 95% |
Source: Pershing Square Capital Management Form 13F-HR for Q1 2026, SEC accession 0001172661-26-002336, parsed from EDGAR and queried from Arkolith production on August 3, 2026.
Which holdings changed most?
Microsoft was the cleanest new line in this comparison. The filing shows 5,654,078 shares with a reported value of about $2.09 billion, instantly making it the fourth-largest disclosed 13F position in the book.
Amazon was the largest add among continuing lines. Pershing Square reported 11,451,981 shares, up from 9,607,824 in the prior comparable filing. That is a 1,844,157-share increase, or roughly 19.2%.
Alphabet moved the other way. The GOOG line fell from 6,163,871 shares to 311,726, and the GOOGL line fell from 678,297 shares to 32,376. Combined reported value across the two classes was only $98.7 million at quarter end. When a fund reports both Alphabet share classes, keep the CUSIP rows separate for source proof, then combine them only when the question is economic exposure. The share-class failure mode is explained further in share classes explained.
Most other top changes were trims, not exits. Brookfield fell 2.8%, Uber 0.8%, Restaurant Brands 1.0%, and Meta 0.5%. Howard Hughes, Seaport Entertainment, and Hertz were held flat by share count in the stored comparison.
How should readers interpret a Pershing Square 13F?
A 13F is useful, but it is not a live portfolio. The SEC's SEC Form 13F FAQ describes it as a quarterly report by institutional investment managers that meet the Section 13(f) threshold. The Form 13F instructions set the familiar deadline: filings are due within 45 days after quarter end.
That lag matters. A Q1 filing accepted on May 15 describes positions as of March 31. It does not prove what Ackman owned in June, July, or today. It also covers reportable U.S. long positions, not short exposure, swaps, cash, debt, foreign ordinary shares outside the 13(f) list, private holdings, or a complete view of Pershing Square's economics.
The filing is still valuable because concentrated managers make the clock easier to read. With only 11 long lines, a new Microsoft position or a near-complete Alphabet reduction is visible without statistical fog. The honest read is narrower: this is what the public filing said about the U.S. long book at quarter end, and this is when the market could inspect it.
Where can I verify the filing?
Start with the SEC accession page, then inspect the rendered fund page. The SEC page proves the filing exists, its acceptance timestamp, and the underlying information table. The Bill Ackman fund page keeps the latest holdings, historical filings, position changes, and source links in one place.
For a programmatic workflow, the same job is one narrow query: pull the fund's latest holdings, ask for quarter-over-quarter changes, and carry the accession number with every position. That is the pattern behind 13F holdings API, how to track institutional ownership changes, and the MCP quickstart.
If the next step is an agent workflow rather than a manual read, connect the data layer, then ask for Pershing Square holdings with the filing accession returned beside each row.
The key discipline is to cite the source clock beside the claim. "Pershing Square added Amazon" is incomplete. "Pershing Square's effective Q1 2026 13F, accepted May 15, showed Amazon shares up 19.2% versus the prior comparable filing" is falsifiable.
What should an analyst watch next?
The next useful question is not whether the Q1 book was "right." It is what the next public filing changes. For Pershing Square, watch four things:
| Watch item | Why it matters |
|---|---|
| Microsoft sizing | A new top-four line becomes meaningful only if it survives or grows |
| Amazon follow-through | A 19.2% add tests whether the position was still being built |
| Alphabet residual | The near-exit can become a complete exit or a rebuilt position |
| Top-six concentration | A concentrated book can change character with one large move |
Those questions are better than a generic copy-trade prompt because they state the uncertainty before the next filing arrives. The data can answer whether the position changed. It cannot answer why the manager changed it unless Pershing Square says so in a separate primary record.
Frequently asked questions about Bill Ackman's 13F
What is Bill Ackman's 13F filer CIK?
The Pershing Square Capital Management 13F filer in this article is CIK 0001336528. The Q1 2026 accession used here is 0001172661-26-002336.
What was Pershing Square's largest Q1 2026 13F holding?
Brookfield Corp. was the largest reported line by value at about $2.42 billion, just ahead of Amazon at about $2.39 billion.
Did Bill Ackman buy Microsoft in Q1 2026?
The effective 13F comparison shows Microsoft as a new reported line with 5,654,078 shares. A 13F proves the quarter-end disclosed long position, not the exact trade date or full economic exposure.
Did Pershing Square sell Alphabet?
The filing shows a sharp reduction, not a complete exit. GOOG and GOOGL together fell by roughly 95% by share count versus the prior comparable filing.
Is this the whole Pershing Square portfolio?
No. Form 13F covers reportable U.S. long securities. It omits many instruments and does not show cash, shorts, swaps, non-reportable foreign holdings, or private positions.
This article reports public regulatory filings and data workflows. It is not investment advice, legal advice, tax advice, or accounting advice.
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