Bill Ackman founded Pershing Square Capital Management in 2004 and runs it as chief executive. The firm is known for two things: a portfolio concentrated in a small number of large stakes, and activism, meaning it buys a big position in a company and then pushes management or the board for changes.
That combination makes Pershing Square one of the easier famous funds to follow in public filings. Its quarterly 13F is short, and its biggest moves often come with a separate SEC filing, a Schedule 13D, or a public announcement from Ackman himself. This guide shows how the pieces fit together.
Pershing Square’s 13F
Form 13F is the quarterly SEC report that institutional managers with at least $100 million in certain U.S.-listed securities must file. It lists long positions at quarter end and is due within 45 days (SEC Form 13F FAQ). Pershing Square files as Pershing Square Capital Management, L.P. on EDGAR.
Each line of the filing names the issuer and class of security, its CUSIP (a nine-character identifier), the market value at quarter end in dollars, the number of shares, and whether the position is a put or call option. Since January 2023, values are reported to the nearest dollar rather than in thousands (SEC FAQ). The filing does not show what Pershing paid or when during the quarter it bought. Our guide to reading a 13F covers every column.
Where many large funds list hundreds of stocks, Pershing’s 13F usually lists about ten. In mid-2025, for example, its reported portfolio held 10 public companies, and the top three (Uber, Brookfield and Howard Hughes Holdings) made up about 51% of it, according to The Motley Fool.
Why concentration changes how you read it
In a portfolio of 300 stocks, a single new line can be a small test position. In a portfolio of ten, every line is a large bet. That has a few consequences for readers:
- New positions are rare and big. When a new name appears, it usually represents a significant share of the fund.
- Exits are meaningful. Selling one of ten holdings is a real change of view.
- Weights move with prices. A stock that rises sharply can become a larger share of the portfolio without any buying, so compare share counts across quarters as well as percentages.
- The 13F misses part of the strategy. Short positions, such as Ackman’s long campaign against Herbalife from 2012 to 2018 (CNN), are not reported on a 13F. Neither are most non-U.S. holdings or private investments.
Where 13D filings fit in
When an investor acquires more than 5% of a company’s voting stock and intends to influence it, the investor must file a Schedule 13D with the SEC. A 13D is filed within days of crossing the threshold, rather than weeks after the quarter ends, and it states the investor’s purpose and plans. Investors without plans to influence the company can usually file the shorter Schedule 13G instead. Our stakes page lists new 13D and 13G filings.
For an activist like Ackman, the 13D is often the first public sign of a new campaign. The 13F that follows confirms the position at quarter end but adds little new.
When Form 4 comes into play
Once an investor owns more than 10% of a company’s registered stock, it becomes an insider under Section 16 of the Securities Exchange Act. From then on, each purchase or sale in that company has to be reported on a Form 4, generally within two business days. That is far faster than a 13F or even a 13D amendment.
Pershing Square’s stake in Howard Hughes Holdings, which it raised to 46.9% in 2025, is well above that line. Trades by Pershing in that stock are therefore reported on Form 4 and appear on our insiders pages along with trades by the company’s officers and directors. Our guide to reading a Form 4 explains the codes.
The practical rule: for a stake under 5%, wait for the 13F. For a stake over 5% with activist intent, watch for the 13D and its amendments. For a stake over 10%, Form 4 gives you the fastest view.
Common mistakes when reading Pershing’s filings
- Treating the 13F as current. It is a quarter-end snapshot filed weeks later. Ackman’s own statements may have overtaken it.
- Reading percentages as buying. A holding’s weight can rise because the stock went up, not because Pershing bought more.
- Missing the vehicle. Pershing Square manages more than one fund. The 13F combines the positions the firm has discretion over, so it does not tell you which fund holds what.
- Ignoring what is not on the form. Short positions, non-U.S. listings and private deals do not appear.
Announcements before filings
Ackman also often discloses positions himself, through investor letters, presentations or posts on X. In those cases the public may learn about a stake before any SEC filing shows it. The 13F then serves mainly as a confirmation and a source for exact share counts at quarter end.
A reading routine for Pershing Square
- When the 13F lands, list the roughly ten holdings and compare share counts with last quarter.
- Check stakes and EDGAR for any 13D or 13D amendment from Pershing Square since the quarter ended.
- Check Ackman’s public statements since quarter end. A position he has announced selling may still appear on the 13F.
- Remember the timing gap. A 13F filed in mid-May describes holdings on March 31.
- Follow Pershing Square on WallStPal so new filings appear on your desk.
Examples
2011 and 2012: Canadian Pacific. Pershing Square disclosed a 12.2% stake in Canadian Pacific Railway on October 28, 2011. A proxy fight followed, and CEO Fred Green resigned on May 17, 2012. Hunter Harrison, a retired railroad executive, became CEO on June 29, 2012, according to a BNN Bloomberg timeline. The campaign is a standard example of how a large disclosed stake can turn into board and management changes.
2016: Chipotle. On September 6, 2016, Pershing Square disclosed a 9.9% stake in Chipotle Mexican Grill in a Schedule 13D, saying it considered the stock undervalued and planned to talk with management and the board about governance and strategy, The Motley Fool reported. The 13D gave the market the news immediately. The next 13F only confirmed it.
2022: Netflix bought and sold between 13Fs. Pershing bought about 3.1 million Netflix shares in January 2022 and sold the entire position on April 20, 2022, for a loss of roughly $400 million. Ackman said the fund had “lost confidence in our ability to predict the company’s future prospects” (CNN). Pershing’s first-quarter 13F, filed in mid-May, still showed the Netflix shares as of March 31, weeks after they had been sold.
2025: Uber announced on X, then Howard Hughes. In February 2025, Ackman revealed in a post on X that Pershing owned 30.3 million Uber shares, built starting in January (The Motley Fool). Because the buying began after December 31, the stake was not in the most recent 13F at the time. Then, on May 5, 2025, Howard Hughes Holdings announced that Pershing Square would buy 9 million newly issued shares at $100 each, a $900 million investment, raising Pershing’s ownership to 46.9%, with Ackman named executive chairman (Howard Hughes press release on EDGAR).
Following Pershing Square on WallStPal
- Find Pershing Square on funds to see each quarter’s holdings, weights and changes.
- See the quarter’s largest moves across famous funds on 13F changes.
- Look up Ackman on famous investors.
Where the data comes from
- Pershing Square’s 13F and 13D filings: search “Pershing Square” on SEC EDGAR
- 13F rules and deadlines: SEC Form 13F FAQ
- Howard Hughes transaction: Howard Hughes Holdings Form 8-K exhibit, May 2025
For how this compares with following Buffett, see following the Berkshire Hathaway portfolio.
Explain it like I’m 13
Most big investment funds are like a giant salad bar: a little bit of hundreds of things. Bill Ackman’s fund is more like a plate with about ten big items on it.
Four times a year, the fund posts a list of what’s on the plate, about six weeks after the fact. But when Ackman buys a big chunk of one company (more than 5%) and wants to change how it’s run, he has to say so within days on a different form called a 13D. Sometimes he just announces it on social media first.
So if you want to follow him, the quarterly list tells you what he owned a while ago. The 13D and his own announcements tell you what he’s doing now.
Questions about this guide? Pal reads it with you and answers in plain English.
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