How to read a 13F filing, line by line: what's in it, what's missing, and how it differs from 13D and 13G

I'm Chris, co-founder of Autopilot. The 13F is the most quoted and least read document in retail investing. Every "what did Buffett buy" headline comes from one, and almost nobody opens the actual filing. Several of our Portfolios are built on these filings, so I read them constantly. Here's how to open one on EDGAR and read it part by part, using Berkshire Hathaway's filing for the quarter ended June 30, 2026 as the worked example, then what a 13F leaves out, why it can be stale the day it's published, and how it differs from the 13D and 13G filings people confuse it with.

One thing first, because we're an SEC-registered investment adviser and I have to say it. Autopilot is the app. The actual investment advice comes from Autopilot Advisers, LLC. If you want the full legal version of anything in here, it's on our disclaimer page.

1) Who files one, and when

Congress passed Section 13(f) of the Securities Exchange Act in 1975 to make institutional holdings public. Under it, an institutional investment manager with investment discretion over one hundred million dollars or more in "Section 13(f) securities" files Form 13F every quarter, within 45 days after the quarter ends; when that day is a weekend or holiday, the deadline moves to the next business day. The SEC publishes the calendar. For the 2026 quarters the dates are May 15, August 14, November 16, and February 16, 2027. There are no extensions.

"Institutional investment manager" is wider than hedge funds. Banks, insurers, pension funds, and broker-dealers that manage money file too. A person managing only their own account doesn't. That's why the funds you follow here are a small slice of the filers, and why a name you've never heard of can have a filing.

2) How to open one

Go to EDGAR's company search on sec.gov, type the filer's name or CIK number, and filter the filing type to 13F-HR. Each filing has its own folder with a primary document, which holds the cover page and summary page, and an information table, which holds the positions. Both are rendered as readable pages. Berkshire's filing for the quarter ended June 30, 2026 was filed on August 14, 2026, the deadline, under Form 13F file number 028-04545. You'll see 13F-HR/A for amendments and 13F-NT for a notice, which means the manager's holdings are reported on someone else's filing. I keep a running list of filer names and CIK numbers for the funds we track in What are 13F filings, and how do you use them to see what hedge funds are buying?.

3) The three parts, and what each line means

The cover page tells you who filed, for which quarter, what kind of report it is, who signed and when, and, on an amendment, whether it restates the filing or adds holdings. The report type matters: a holdings report has everything, a notice has nothing, and a combination report has part of it, with the rest on another manager's filing.

The summary page has three numbers you should read before the table. The entry total is the number of line items. The value total is the fair market value of everything reported, as of the quarter's end, rounded to the nearest dollar; before January 3, 2023 the form rounded to the nearest thousand dollars, which is why older filings look a thousand times smaller than they are. And the list of other included managers names the affiliates whose holdings are folded in. Berkshire's lists fourteen, mostly its insurance subsidiaries.

The information table is the part everyone quotes. Each line has the issuer's name, in alphabetical order; the title of the class, such as common stock, a share class, or a put or call; the CUSIP and, optionally, a FIGI identifier; the value to the nearest dollar; the number of shares or principal amount, flagged SH or PRN; a put/call flag if it's an option; the type of investment discretion, sole, defined, or other; which of the other included managers the line belongs to; and voting authority split into sole, shared, and none. One thing catches everyone: the same company can appear on many lines, because each subsidiary that holds it gets its own line. Add them up before you conclude anything about size.

4) What a 13F leaves out

A lot, and every gap matters if you're trying to reverse-engineer a strategy. Short positions aren't reported at all. Only securities on the SEC's Official List of Section 13(f) securities are, which is mainly US exchange-traded stocks, closed-end funds, and ETFs, plus certain convertible debt, equity options, and warrants; mutual funds, cash, ordinary bonds, private holdings, and stocks listed only outside the US aren't on it. The value is a snapshot as of the last day of the quarter, on a trade-date basis, and says nothing about what happened between quarter ends. A manager can also ask the SEC for confidential treatment of a position for a period, so a filing can be complete on its face and still be missing something.

Then there's the lag. The filing can arrive 45 days after the quarter ends and describes positions as of that quarter end. By the day you read it, the manager has had those 45 days, plus however long since, to change everything. Our tracker Portfolios follow the filings, not the fund's live book, and every tracker fact sheet says so. I went through what that lag does to a follower in How to see what Berkshire bought: reading the 13F, the amendments, and the 45-day gap.

5) What it does tell you about strategy

Read across quarters, a 13F is a decent map of how a manager thinks. Concentration: how many lines there are and how much of the value total sits in the top few. Turnover: what appeared, disappeared, or changed size since the prior quarter. Instruments: whether put and call lines show up, which means options are part of the toolkit. Structure: whether holdings are spread across affiliates. Consistency: whether the same names persist for years or the whole table changes every filing.

What it can't tell you is why, what's hedging what, what's shorted against it, when the trades happened, or how the fund actually did. For that you need the fund's own reporting, which you usually can't get, or, for the Portfolios we publish, the fact sheet, which shows what follower accounts did rather than what the fund did. I wrote the difference up in How hedge funds actually run money: what a 13F shows, what it hides, and what that means for you.

6) 13F versus 13D versus 13G

They answer different questions. A 13F is about a manager: its whole portfolio of reportable securities, once a quarter, filed by the manager. A 13D is about a company: anyone who crosses five percent of a class of a company's shares and intends to influence control files one within days of the event, which is why 13Ds often precede activist campaigns and takeover fights. A 13G is the shorter, passive version for holders over five percent with no such intent, available to institutions buying in the ordinary course of business, to passive investors, and to certain exempt holders, each with its own deadlines and amendment rules. Taking activist steps disqualifies a filer from 13G and requires a 13D. If you want to know what a fund owns, read the 13F. If you want to know whether someone is about to fight a board, read the 13D.

Frequently asked questions

How do I read a 13F filing?

Open EDGAR, search the filer, and filter to 13F-HR. Read the cover page for the quarter and report type, then the summary page for the entry total, the value total (rounded to the nearest dollar since January 3, 2023, and to the nearest thousand before that), and the list of other included managers. Then read the information table: each line has issuer, class, CUSIP, value, share count, a put/call flag, discretion type, which affiliate holds it, and voting authority. The same company can appear on several lines; add them up.

Why might a hedge fund's 13F not reflect their current real positions?

Because it's a snapshot as of the quarter's last day, filed up to 45 days later, so positions can be weeks or months old on the day you read them. It reports only Section 13(f) securities, mainly US-listed stocks, closed-end funds, ETFs, and certain options and convertibles, so shorts, cash, ordinary bonds, private holdings, and non-US-listed stocks are absent. A manager can also receive confidential treatment for a position for a period, and options lines can hedge stock lines in ways the table doesn't explain.

What does a hedge fund's 13F tell you about its strategy?

Read across quarters, it shows concentration (how many lines, how much sits in the top few), turnover (what appeared, disappeared, or changed size), whether options are in use (put and call flags), how holdings spread across affiliates, and whether the same names persist over years. It cannot tell you why a position exists, what hedges it, what's shorted against it, when trades happened, or how the fund performed. Treat it as a map of thinking, not a record of results.

What is the difference between 13F, 13D, and 13G?

A 13F is a manager's quarterly report of its whole portfolio of reportable US securities, filed by managers with investment discretion over one hundred million dollars or more. A 13D is filed by anyone who crosses five percent of a company's share class and intends to influence control, within days of the event, and often precedes activism. A 13G is the shorter passive version for holders over five percent without that intent; taking activist steps requires switching to a 13D. Use the 13F to see what a fund owns and the 13D to see who is about to fight for control.

TLDR

A 13F is a quarterly snapshot, filed up to 45 days later, of a manager's US-listed long positions and certain options, in three parts: cover page, summary page, information table. Read the value total's rounding, add up the lines per company, and remember what isn't there: shorts, cash, non-US stocks, private holdings, timing, and the reason why. Across quarters it maps how a manager thinks; it never records how they did. 13D and 13G are about crossing five percent of one company, not about the whole portfolio.

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