How to Read a 13F Filing: Track What Hedge Funds and Buffett Are Buying

13F Filings at a Glance

What a 13F Actually Is

A Form 13F is a quarterly disclosure required by Section 13(f) of the Securities Exchange Act of 1934. Any institutional investment manager — hedge fund, mutual fund, pension fund, insurance company, or bank trust department — that exercises investment discretion over $100 million or more in "13(f) securities" (a list of roughly 5,000-plus mostly US-exchange-listed stocks, some ETFs, and select convertible instruments that the SEC updates quarterly) must file one within 45 days of each quarter's end.

The filing itself is a plain table: each row lists a security (by name and CUSIP number), the number of shares held, and the market value as of quarter-end. There's no explanation of why the fund bought or sold anything — just the raw numbers.

Step by Step: Finding a 13F on SEC EDGAR

• Go to SEC EDGAR's company search at sec.gov/cgi-bin/browse-edgar and search for the fund's name (e.g. "Berkshire Hathaway") in the company name field.
• In the results, find the entity matching the fund's investment management arm (large firms sometimes have several related entities — look for the one that files 13F-HR forms, not 10-Ks or other filings).
• Filter the filing type field to "13F-HR" and click Search — this returns every quarterly filing that fund has made, most recent first.
• Open the most recent filing and click into the "INFORMATION TABLE" document (not the cover page) — this is the actual holdings list with shares and values.
• To see what changed, open the prior quarter's filing the same way and compare share counts line by line — EDGAR doesn't do this for you natively.

Worked Example: Reading a Position Change

Say a fund's Q1 2026 13F shows 2,000,000 shares of a stock, and its Q2 2026 13F shows 3,500,000 shares of the same stock. Here's what that comparison tells you — and doesn't:

The filing won't tell you at what price the fund bought those extra shares, whether it has since sold them (the next 45-day-delayed filing is your only way to find out), or whether it's simultaneously short the same stock through a vehicle not covered by 13(f) reporting.

What a 13F Can't Show You

• Short positions — 13Fs are long-only disclosures; a fund's short book (however large) never appears.
• Non-US-listed foreign stocks and most bonds/commodities — only Section 13(f)-listed securities are reportable.
• Private company stakes, real estate, and pre-IPO holdings — none of that is a 13(f) security.
• Exact trade timing or price paid — only the quarter-end snapshot of shares and market value.
• The fund's reasoning — 13Fs are pure numbers, no commentary or thesis included.
• Real-time changes — a position could be fully exited the day after quarter-end and still show as "held" on the filing you're reading 45+ days later.

Bottom Line

13F filings are one of the few free, mandated windows into what the largest institutional investors — including Warren Buffett's Berkshire Hathaway — are doing with their US equity portfolios. Used correctly, they're a great way to understand a fund's sector tilts, conviction levels, and long-term philosophy shifts over multiple quarters.

Used incorrectly — as a real-time trading signal to copy — they're stale, incomplete (no shorts, no reasoning, no price), and have a track record of underperforming simpler approaches. Read 13Fs for insight into how the best investors think, not for a shortcut to their next trade.

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