About 13f-changes

13f-changes tracks quarter-over-quarter changes in selected hedge funds' Form 13F-HR filings with the SEC. Unlike most 13F tools, the site is organized around what shifted rather than the static list of holdings.

What's a 13F?

Form 13F-HR is a quarterly disclosure filed by institutional investment managers with at least $100 million in qualifying U.S. equity securities under management. It lists every long equity position held at quarter-end. Filings are due 45 days after the quarter ends.

What 13Fs cover

• Long equity positions in U.S.-listed common stock, ADRs, and certain ETFs.
• Listed call and put options, reported separately from the underlying.
• Convertible debt and certain warrants.

What 13Fs don't cover

• Short positions.
• Bonds and most fixed-income holdings.
• Foreign-listed shares not on U.S. exchanges.
• Derivatives positions held outside the reporting entity.
• Currency, commodity, or futures positions.
• Anything held in non-13F-reporting vehicles.

Data sources

• Filings: SEC EDGAR (www.sec.gov), the primary source.
• CUSIP to ticker: OpenFIGI free API.
• Sector / industry: Yahoo Finance via the yahoo-finance2 library, mapped to canonical GICS top-level sectors.
• Latest prices: Yahoo Finance quotes refreshed into a static JSON snapshot.
• Themes: assigned editorially per-fund during a quarterly review session. Themes are an opinionated layer on top of the canonical sector data.

Refresh cadence

A GitHub Action polls EDGAR every 30 minutes during the active filing-window days in February, May, August, and November. When a new filing lands, a manual review session ingests it, classifies any new positions, computes the diff, and ships. A separate weekday workflow refreshes the latest-price snapshot around 6pm EST.

Limitations

• No trade tape. 13Fs disclose quarter-end holdings, not the date, price, or sequence of buys and sells. "New," "closed," and "buy / sell activity" are inferred from adjacent quarter-end snapshots.
• 13F price is a quarter-end mark. The 13F price columns divide reported value by reported shares for ordinary share rows. They are not the fund's execution price.
• Exposure shifts are not the same as activity. Exposure-shift charts compare quarter-end portfolio weights, so performance can affect them. Activity charts estimate buys and sells from share-count changes at 13F marks and exclude unchanged positions.
• Closed-position gains are not knowable from 13Fs alone. A closed row only says the position was present at the prior quarter-end and absent at the current quarter-end. The site can show the stock's market range during that quarter, but not the fund's realized gain or cost basis.
• Since q-end is mark-to-market context. Since q-end compares the latest price snapshot to the quarter-end 13F price for still-held ordinary equity rows. It does not estimate realized P/L, execution price, taxes, fees, or short exposure.
• Options vs. underlying. Listed options on the same security are shown as separate rows, with a "Call" or "Put" annotation. Option rows may show the underlying stock's price change since quarter-end, but that is directional context rather than option P/L.
• Foreign-listed shares. Some foreign-listed CUSIPs (G-prefix) are present; resolution to local tickers is best-effort.
• Theme tags are editorial. Different observers would categorize positions differently; tags are one perspective.