About 13FAI

What we do

13FAI tracks the public equity holdings of the world's most closely followed institutional investors — from Warren Buffett's Berkshire Hathaway to Bill Ackman's Pershing Square. Every quarter, we pull 13F filings directly from the SEC and make the data easy to explore: see what each fund owns, what changed, and which stocks are attracting the most hedge fund attention.

We also use AI to generate plain-language insights on each fund and stock page — summarizing key position changes, new bets, and exits so you can understand the data at a glance without reading a spreadsheet.

Data source & methodology

All holdings data comes from 13F-HR reports filed with the SEC. From each filing we calculate each fund's portfolio weight per position (value ÷ total reported equity), reported price (value ÷ shares held), and period-over-period share count changes vs the prior quarter and prior year.

Where funds report options positions (PUT/CALL), we display them in the holdings table for transparency but exclude them from all portfolio value, weight, and share count calculations. Options represent hedges or directional bets rather than direct equity ownership, and including them would distort the long equity picture.

Update schedule

13F filings are due to the SEC within 45 days of each quarter end — March 31, June 30, September 30, and December 31. Most large funds file within the first two weeks of the deadline window. We update our data as filings become available, typically completing each quarterly cycle by mid-February, mid-May, mid-August, and mid-November. You can track expected filing dates on our Filing Calendar.

Limitations

13F filings have important limitations. They are filed 45 days after quarter end, so positions shown may no longer reflect a fund's current holdings. Funds managing less than $100M in US equities are not required to file. Short positions, bonds, foreign-listed stocks, and private investments are not disclosed. For a full explanation, see our Education page and Disclaimer.