A 13F is a quarterly report that US investment managers with more than $100 million in certain securities file with the SEC. It lists what they held on the last day of the quarter: each stock, the number of shares and the value. It's how anyone can see what Warren Buffett's Berkshire Hathaway or Bill Ackman's Pershing Square owns.
What's in it
- US-listed stocks and some ETFs, options and convertible bonds, as of quarter end
- shares held and their market value on that day
- nothing about the price paid or when within the quarter they bought
What's not in it
- Short positions. A fund can look bullish on a stock it is hedging.
- Cash, bonds and non-US holdings. For a global fund, the 13F can be a small slice of the book.
- Anything recent. Filings are due 45 days after the quarter ends, so the newest one is at least six weeks old when it appears, and can be four and a half months old by the time the next arrives.
- Some positions temporarily. Managers can ask the SEC to keep a position confidential while they are still building it.
How to use it
- Look at changes, not just holdings. A new position or a large add says more than a stake held for ten years.
- Weight by conviction. A 20% position matters; a 0.1% position may be a rounding error or a trade for a client.
- Treat it as a starting point. Copying a 13F means buying months later, at a different price, without the reasons. Use it to find companies worth researching yourself.
See it in practice
The superinvestor pages show each investor's latest 13F with the quarter's new positions, adds, trims and sales, and every stock page lists which of them own it.
For education, not investment advice.