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About this site

What this site is, and isn't

What it does

This site tracks the U.S.-listed public equity portfolio Berkshire Hathaway discloses to the SEC each quarter on Form 13F-HR: the buys, sells, and trims (Portfolio Activity), the current weighting of every position (Holdings), the full history of filing dates (13F Archive), and how the stock has performed against the S&P 500 (Performance).

What it isn't

It isn't affiliated with, endorsed by, or run by Berkshire Hathaway Inc., Warren Buffett, Greg Abel, or the U.S. Securities and Exchange Commission. "13F" filings only capture U.S.-listed long equity positions — they leave out Berkshire's wholly-owned subsidiaries (insurance, railroads, utilities, manufacturing), private and non-U.S. holdings, and cash. The portfolio shown here is a slice of Berkshire, not the whole company.

Where the data comes from

Holdings and filing dates are sourced from Berkshire Hathaway's public 13F-HR filings, cross-referenced against SEC EDGAR and third-party trackers including ValueSider and 13f.info. Performance figures use BRK.B and S&P 500 (SPY) total returns sourced from PortfoliosLab. Every page links its specific sources in the footer.

How the updates work

Most of this site updates itself. A script (cron/update-13f.php) runs on a schedule and checks SEC EDGAR for a new Berkshire Hathaway 13F-HR filing. When one appears, it downloads the filing's information table directly from SEC.gov, parses every disclosed position, and:

  • rewrites the Holdings table with the new weights;
  • compares the new share counts against the previous filing and computes the Portfolio Activity log automatically — every new position, addition, trim, and full exit, not just the ones newsworthy enough for a headline;
  • appends a new row to the 13F Archive.

Two things on this site are not pulled automatically, on purpose, because there's no reliable structured source for them: cash & equivalents (Berkshire's own XBRL cash tag stopped being consistently machine-readable years ago, so that figure is checked by hand each quarter against the 10-Q) and the Japanese trading-house stakes (foreign-listed holdings never appear in a 13F at all, and Berkshire discloses stake changes irregularly rather than on a fixed schedule). Both are labeled on the Holdings page with the date they were last verified, rather than presented as live.

13F filings are due 45 days after each quarter ends (mid-February, mid-May, mid-August, and mid-November) — the update script is scheduled to check daily, so a new filing is typically reflected within a day of becoming public.

Not investment advice. Nothing on this site is a recommendation to buy or sell any security. See the full Terms & Disclaimer.

Companion site

A sister site, buffett.online, covers Berkshire's current portfolio snapshot across multiple languages. This site is the deeper, activity-focused companion: full history rather than a single point-in-time view.

Questions or corrections

Spot an error, or have data to contribute? See the Contact page.