How we rank activist investors

Where the numbers come from

We follow a fixed list of well-known activist investors (24 active today; see the investor profiles) and read every relevant filing they make with the U.S. Securities and Exchange Commission. Three kinds of filing matter:

• Schedule 13D and 13D/A. Anyone who acquires more than 5% of a company's voting shares and may seek to influence it must file a Schedule 13D within five business days, stating how many shares they own and why they bought them (Item 4, “purpose of the transaction”). Every material change to that stake requires an amendment, the 13D/A. This is the classic signal that an activist campaign has started.
• Form 4. Once an investor owns more than 10% of a company, or has a seat on its board, each purchase or sale must be reported within two business days with the exact number of shares and the price. These are our most precise figures.
• Form 13F-HR. Investment managers with $100 million or more in U.S.-listed stocks report their long holdings every quarter, within 45 days of the quarter end. Comparing a fund's latest 13F with its previous one shows what it bought and sold during the quarter.

Filings are read from EDGAR's machine-readable XML wherever it exists. Schedule 13D has been filed in structured XML since December 2024, Form 4 and 13F for much longer.

How a filing becomes a move

Each relevant filing becomes one or more moves: a dated buy, sell or update in one company. The badge on each row of the table names the move.

Investors who file under more than one SEC identity (for example a fund and its founder) are combined, and each filing is counted once even when it appears under several identities.

What the value column means

Not every filing states a dollar amount, so every value carries its basis:

• Plain figure, transaction value. From a Form 4: shares × the price the investor actually paid or received, as reported.
• “est.”, estimated value. From a Schedule 13D or 13D/A, which report shares but not a total cost. We multiply the shares by the stock's closing price on the date of the event. It is a fair-value estimate, not the price paid.
• “13F”, 13F-reported value. The change in shares × the per-share value the fund reported for the quarter end. Funds report quarter-end values, not purchase prices.
• “—”, no value. The filing does not let us value the change, for example a 13D/A whose earlier filing could not be read. These moves still appear but add nothing to the ranking.

Date invested vs. date filed

Date Invested is when the investment happened: the trade date on a Form 4, the date of the event that triggered a 13D, or, for a 13F, the quarter the holding was reported for (shown as, say, “Q3 2026”, because 13Fs don't say when in the quarter a trade was made). Filed is the day the filing became public on EDGAR, which is the date that decides which edition a move belongs to.

How the Top 10 is ranked

For every tracked investor with at least one move in the edition's window we add up:

1. Disclosed buying: the total value of their counted buy moves;
2. New campaigns: the number of first-time Schedule 13D filings;
3. Disclosed selling: the total value of their counted sell moves;
4. Filings: the number of distinct filings.

Investors are sorted by disclosed buying, highest first. Ties are broken by new campaigns, then disclosed selling, then number of filings, then name. The first ten make the Top 10. Arrows show the change from the previous edition; “New” means the investor was not ranked last time.

No double counting

The same purchase can surface in several filings. If an investor reported Form 4 purchases or sales in a company during the window, their 13D/A and 13F moves for that company are kept for context but marked not counted; a 13F move is likewise not counted when a 13D move for the same company exists in the window. Form 4 has the actual price, so it wins.

Carry-over entries

Some fortnights fewer than ten tracked activists file anything. We never pad the table with invented data. Remaining ranks are filled with carry-over entries, the investors with the most recent buying filed in the previous 90 days, clearly labelled and showing the older filings with their filed dates. A carry-over never repeats a move that is still in a locked Premium top five of an earlier edition. If even that is not enough, the edition simply has fewer than ten rows.

Sanity checks

Before anything is published, every move passes automated plausibility checks. Any single value above $50 billion is dropped, as is any per-share price outside half to double the stock's market close on that date. Each dropped move is logged for review, so one malformed filing cannot distort a ranking.

Editions and the premium window

Editions publish on the 1st and 15th of every month at 7:00 a.m. ET. Each covers filings by the date they were filed, inclusive:

• the 15th edition covers the 1st through the 14th of the same month;
• the 1st edition covers the 15th through the last day of the previous month.

For the first 30 days after publication, ranks 1–5 are reserved for Premium subscribers; free readers see ranks 6–10. In a quiet window, the lower ranks unlock with the rest of the edition. Nothing about ranks 1–5 is published on the site during that window except one rounded teaser figure: their combined disclosed buying, rounded to two significant figures (to the nearest $1 million for a total in the tens of millions, the nearest $10 million in the hundreds of millions) and shown as approximate. A locked edition also withholds its volume counts, the number of filings reviewed and of moves, until it unlocks. Investor profiles list SEC filings only through the end of the newest unlocked edition's window, for every investor alike, so a profile cannot hint at who holds ranks 1–5; newer filings appear as each edition unlocks. Profile holdings, and the crowded trades built from them, use each investor's latest 13F filed by that same cutoff, so a newer 13F appears when its edition unlocks. After 30 days the edition becomes free in full.

Tickers and prices

Company tickers come from the SEC's own company list. Where a filing identifies a security only by its CUSIP, we match it with OpenFIGI, falling back to the company name. Closing prices, used for estimated values and the track record, come from a public market-data feed and use the nearest earlier trading day when a date falls on a weekend or holiday.

Track record

The track record follows every counted buy with a ticker that has appeared in a public edition. The entry price is the close on the day the filing became public, the first day a reader could have acted, not the price the activist paid. Returns are shown to the latest close and, once enough time has passed, at three weeks and three months, next to the S&P 500 (SPY) over the same dates. Hit rate is the share of tracked buys trading above their entry price.

Notes and AI

Some moves carry a one-sentence note on why the filing matters, and Schedule 13D moves quote the filer's own stated purpose. Notes may be drafted by an AI model, but only from the filing's own text, and they are checked automatically: a note containing any figure that does not appear in its source filing is thrown away and replaced by a plain template sentence. Rankings, shares, values and dates never come from AI.

Limitations

• Filings lag the trades they describe: up to five business days for a 13D, two for a Form 4, and up to 45 days after the quarter for a 13F.
• Estimated and 13F values are fair-value estimates, not the prices the investor paid.
• Activists sometimes hold economic exposure through derivatives or swaps that these filings do not fully capture.
• We cover the activists on our list, not every investor who files a Schedule 13D.
• Automated parsing can make mistakes. Every row links to its filing so you can check it.

Nothing here is investment advice. Please read the disclaimer.

Open data and corrections

The public data behind the site is available as JSON: the latest edition, the edition index, investor profiles, crowded trades and the track record. Feeds are available as RSS, Atom and JSON Feed.

Found something that doesn't match its filing? Tell us and we will check it against EDGAR and correct it.