What Is an SEC 13F Filing? A Beginner’s Guide

If you have ever read a headline like "Warren Buffett just bought a new stock," the source was almost certainly a 13F filing. It is one of the most powerful free tools available to everyday investors — a quarterly window into what the world's largest funds are holding.

What is a 13F filing?

Form 13F is a quarterly report that institutional investment managers with at least $100 million in qualifying U.S. equity assets must file with the U.S. Securities and Exchange Commission (SEC). It lists the stocks, ETFs, and options the manager held at the end of the quarter, along with share counts and market values.

Who has to file one?

Any institutional manager crossing the $100 million threshold — hedge funds, mutual funds, pension funds, insurance companies, and family offices — must file within 45 days of the quarter's end. That is how the public gets to see the holdings of investors like Warren Buffett, Michael Burry, and Cathie Wood.

What a 13F does not show

13F filings are powerful but imperfect. They come with a reporting lag of up to 45 days, so positions may have changed by the time you see them. They generally exclude short positions, cash, and most international holdings, and they only capture a snapshot from the final day of the quarter. Treat them as a research starting point, not a real-time trade signal.

How investors use 13F data

• Discover new ideas by seeing which stocks respected funds are adding.
• Gauge conviction by tracking how position sizes change over time.
• Spot themes when many top funds crowd into the same sector.
• Study the long-term approach of legendary value and growth investors.

Track 13F filings with StockInsider

StockInsider organizes 13F data into clean, followable portfolios so you don't have to dig through raw SEC documents. Build a watchlist of the investors you admire and get notified when new filings land.