What Is a 13F?

A 13F is a report that large investment managers must file with the U.S. Securities and Exchange Commission every three months, listing the US stocks they held at the end of the quarter. Any manager with at least $100 million in US-listed shares has to file one, which is why a 13F is the main public window into what hedge funds, pensions and other big institutions own.

The filing is useful, but it is easy to misread. It arrives up to 45 days late, it leaves out short positions and hedges, and it shows a single moment in time. A 13F is straightforward once you know what to look for: who files, the deadline, what it shows and hides, how to read one and how a long-term investor should use it.

(For anyone who arrived here from a military search, "13F" is also an Army job code for a fire support specialist. This article is about the SEC filing, not the Army role.)

TL;DR: what is a 13F

• What it is: a quarterly SEC filing of an institution's US stock holdings.
• Who files: managers with $100 million or more in US-listed securities.
• When: within 45 days after each calendar quarter ends.
• What it shows: long stock positions, some options and convertibles - ticker, shares and market value.
• What it hides: short positions, cash, bonds, most foreign stocks and anything below the reporting rules.
• Why it is delayed: the 45-day window, plus confidential-treatment requests, mean you are always seeing an old snapshot.

What is a 13F filing?

A 13F filing is a quarterly disclosure of the stocks a large institution owns. The name comes from Section 13(f) of the Securities Exchange Act of 1934, the law that created it. Congress added the rule in 1975 so the public and regulators could see what the biggest investors were doing, on the theory that transparency into institutional holdings supports confidence in the markets.

The form is filed with the SEC and becomes public. It reports positions as of the last day of the quarter, the "period of report," not as of the filing date. That gap matters.

Who has to file a 13F?

The rule applies to "institutional investment managers" that exercise investment discretion over $100 million or more in Section 13(f) securities. Investment discretion means the manager decides what to buy and sell, whether for its own account or for clients.

That threshold pulls in most of the large players investors care about:

• Hedge funds
• Mutual fund companies
• Pension funds
• Banks and trust departments
• Insurance companies
• Registered investment advisers

Once a firm crosses $100 million, it must file for that quarter and keep filing. A small fund below the threshold does not file, so a 13F database will never show every institution - only the large ones.

What does a 13F show, and what it hides?

This is the part most people get wrong. A 13F is a partial picture by design. It reports long positions in a defined list of securities, and nothing else.

Because shorts and hedges are invisible, a book that looks aggressively bullish on paper may be carefully hedged in reality. A fund could report a large stock position that is actually offset by options you never see. Reading a 13F as "this manager is betting everything on these names" is the classic mistake.

What are 13F securities?

Only holdings on the SEC's official list of Section 13(f) securities have to be reported. The SEC publishes and updates this 13F securities list every quarter. It covers:

• Exchange-listed stocks
• Exchange-traded funds (ETFs)
• Certain equity options
• Some convertible notes and warrants

If a holding is not on the list, it does not appear in the filing, even if it is one of the fund's largest positions. That covers a private company stake, a bond, a commodity or most non-US shares.

When are 13F filings due? The 45-day deadline

A 13F is due within 45 days after the end of each calendar quarter. There are four filing dates a year, one per quarter:

Say a fund buys a stock on January 2. That trade lands in the quarter ending March 31, and the manager has until May 15 to file. By the time you read about the position, more than four months may have passed, and the manager may have already sold it.

Managers can also ask the SEC for confidential treatment of a position, which lets them delay disclosing a holding they are still building. When the request is granted, that position stays hidden until later. So 45 days is the least stale the data gets. Often it is worse.

How to read a 13F: a worked example

Once you have a filing, reading it is straightforward. Imagine a fund reports these top holdings for the quarter:

A few things to look for:

• Position size. Company A is 30% of the reported book, so it matters far more to this manager than a 1% position would.
• Quarter-over-quarter change. Compared with last quarter, a holding can be new (bought this quarter), added to, trimmed or sold out entirely. The changes often say more than the snapshot.
• Conviction versus noise. A large, long-held position signals more about a manager's thinking than a tiny new stake that might be a placeholder or a hedge leg.

Now the traps. The 45-day lag means Company C may already be gone. The missing shorts mean the book may be hedged in ways the table cannot show. And the percentages only cover reported securities, so a fund with big cash or bond holdings is more diversified than its 13F alone suggests.

Where to find 13F filings

You have two main routes:

• SEC EDGAR. The SEC's EDGAR system is the free, primary source. Every 13F is posted there, and you can search by the manager's name. The raw filings are complete but not pretty.
• Third-party 13F databases. Many sites clean the raw filings into readable tables and track changes over time. They are convenient, but you are trusting their parsing, so the primary source is worth checking for anything important.

MoatMint keeps its own readable roster. Our superinvestor 13F portfolios pages track the reported holdings of well-known managers like Warren Buffett and Michael Burry, with each portfolio's largest positions and quarter-by-quarter activity, so you can see what great investors own without wading through raw filings.

How long-term investors should use 13Fs

A 13F is a research starting point, not a trading signal. The people who lose money with these filings are the ones who see a famous investor's name, buy what they bought and call it a strategy. The data is stale, the shorts are hidden and the manager's goals are not yours.

Used well, a 13F is an idea generator. When a disciplined manager you respect keeps holding a business quarter after quarter, that is a prompt to go study the company - not a reason to buy it blind. From there, the work is the same as any other stock: judge the business on its own merits.

• Check whether it has a durable economic moat that protects its profits.
• Ask whether it is a genuinely quality business, not just a popular one.
• Decide how it fits a concentrated or diversified portfolio, since most great managers run concentrated books.
• Plan to hold with discipline, because holding winners is where long-term returns come from.

To turn that into a repeatable process, you can screen for quality yourself and read how the MoatMint rating works to see how we summarize the evidence on a business in one place. The 13F points you toward interesting names; the research tells you whether they deserve your capital.

A 13F rewards curiosity and punishes imitation. Read it to learn what serious investors are studying, then do your own homework.

This article is for informational and educational purposes only. It is not investment advice or a recommendation to buy or sell any security.