How to Read 13F Filings | SEC Filing Guide for Investors

Learn how to read SEC 13F filings to track what top fund managers are buying and selling.

Educational Guide February 23, 2026 • 9 min read • By Theo Ledger

SEC Form 13F is a quarterly report filed by institutional investment managers with over $100 million in qualifying assets. It is the main public window into what large investors own. But it has gaps that regularly mislead people who read it at face value.

Last Updated: November 1, 2026

What is a 13F Filing?

Created by Congress in 1975 to increase public confidence in U.S. financial markets, the SEC 13F filing mandates that large institutions publicly disclose their U.S. equity investments. This includes mutual funds, hedge funds, pension funds, and insurance companies.

This is how the public learns exactly what Warren Buffett, Michael Burry, and other titan investors are buying and selling.

The Rules (And The Gaps)

To use 13F data successfully, you must understand what is—and what isn't—included in the filing.

1. The 45-Day Delay

This is the most critical rule. Institutions are required to file their 13F 45 days after the end of the calendar quarter.

The Trap: By the time you read a 13F on May 15th, you are seeing what the fund held on March 31st. A highly active fund might have completely sold out of a position during those intervening 45 days.

2. Only U.S. Traded Equities Are Required

A 13F filing only requires disclosure of "Section 13(f) securities." These are generally U.S. exchange-traded stocks, ETFs, and certain convertible bonds. It does not include:

3. The Big Blind Spot: Short Positions Are Hidden

The SEC does not require institutions to disclose their short positions on a Form 13F. This is crucial when tracking hedge funds. A fund might show a massive long position in a specific tech stock on their 13F, but they could actually be heavily net-short the entire tech sector through undisclosed derivatives.

While Call and Put options are disclosed on a 13F, the specific strike prices and expiration dates are not, making it impossible to know the true leverage or timeframe of the options trade.

4. Options Are Shown at the Value of the Shares Behind Them

A 13F reports an option position at the notional value of the underlying shares, not at what the option cost. That can make a small bet look like a huge one, and a bet against a stock look like a large holding of it.

Michael Burry's final Scion 13F, for Q3 2025, is the clearest example. The two largest lines, Palantir at 66% and Nvidia at 13.5% of disclosed value, were put options, which gain if those shares fall. Read as ordinary shareholdings, the filing says Burry was heavily long two AI stocks when he was betting against both. Always check the put/call column before reading a 13F line as a holding. Our Scion page labels each one.

5. One Company Can Appear on Several Lines

Each line is identified by a nine-character CUSIP, and different share classes of the same company have different CUSIPs. Alphabet's A and C shares, for example, are separate securities. Add the lines together if you want a manager's total exposure to one company. And never match securities on a shortened CUSIP: the first six characters identify the issuer, not the security, so truncating them merges share classes and loses the ticker.

6. Filings Can Simply Stop

The obligation applies to registered managers above the $100 million threshold. A manager who closes a fund or deregisters stops filing. Scion was wound down in October 2025 and deregistered with the SEC on 10 November 2025, so its Q3 2025 filing is the last one that will ever exist. A tracker that still calls such a fund "active" is out of date.

How to Actually Use 13F Data

Given the 45-day delay and hidden shorts, you should never blindly "copy-trade" a 13F. Instead, use them as a powerful screening tool.

When an investor with an incredible track record establishes a brand new position in a company, it signals high conviction. The 13F tells you where the smart money is looking. Your job is to go research the underlying company to find out why they bought it.

See it in practice: our Berkshire Hathaway and Scion pages are built from these filings, keyed on full CUSIPs with options labelled. For a manager that doesn't have the 45-day delay, see ARK Invest's daily trades: ARK publishes its ETF holdings every trading day.