What Is a 13F Filing? How to Read a Hedge Fund's Holdings

Updated Oct 28, 2026 · 3 min read

A 13F (officially Form 13F-HR) is a quarterly report that large investment managers file with the US Securities and Exchange Commission. It lists the US-listed stocks and certain other securities they held on the last day of the quarter. It is the reason anyone can look up what Warren Buffett's Berkshire Hathaway or Bill Ackman's Pershing Square owns.

Who has to file a 13F?

Any institutional investment manager with discretion over at least $100 million in "13(f) securities" (mainly US-listed stocks, ETFs, some convertible bonds and listed options) must file. That includes hedge funds, mutual fund companies, banks, insurers, pension funds and family offices. The filing is made by the firm, not the famous person associated with it.

When are 13Fs due?

Within 45 days of each calendar quarter's end, so around February 14, May 15, August 14 and November 14. Most big funds file in the last few days before the deadline. That means a 13F can describe a portfolio that is already six weeks to four and a half months old.

What a 13F shows

• Each position's issuer, share class, CUSIP, number of shares and market value at quarter end.
• Whether a line is a put or call option (shown as the value of the underlying shares, not the option's price).
• Comparing two quarters reveals what was bought, added to, trimmed and sold.

What a 13F doesn't show

• Short positions, cash, bonds, most foreign-listed shares, private investments and derivatives other than listed options.
• Trades inside the quarter. A stock bought in April and sold in May never appears.
• Confidential positions. Funds can ask the SEC to delay disclosing a position they're still building; it appears later in an amendment (13F-HR/A).
• Intent. A position can be a hedge, part of a pair trade or a small experiment.

How to read one without fooling yourself

Look at position size (percentage of the reported portfolio) before anything else: the top five holdings usually say far more about a manager's conviction than the long tail. Watch new positions and big adds, but remember they reflect decisions made weeks or months ago. And treat options lines carefully: Michael Burry's famous puts show up as large "positions" even though the money at risk was far smaller.

Can you profit by copying 13Fs?

Copying works best for patient, concentrated, low-turnover managers, where a 45-day delay barely matters, and worst for fast-trading funds whose book has changed by the time you see it. We tested it: see our 10-year backtests of copying Berkshire, copying Pershing Square and a 12-fund consensus portfolio, all measured against simply holding the S&P 500.

Browse the latest filings on our famous investors page, including Warren Buffett, Michael Burry and Bill Ackman.