What is a Form 4? How to read SEC insider transaction filings

A Form 4 is the document a company insider - an officer, director, or beneficial owner of more than 10% of a class of equity securities - must file with the U.S. Securities and Exchange Commission after buying or selling that company's stock. Under Section 16 of the Exchange Act, the filing is generally due within two business days of the transaction.

Every Form 4 is public. That is why Form 4 data is one of the most reliable windows into what executives and directors actually do with their own money - not what they say on earnings calls.

Three groups count as Section 16 "insiders": corporate officers (typically CEO, CFO, and other named officers), members of the board of directors, and anyone who beneficially owns more than 10% of a voting class of the company's equity.

Related forms fill out the picture. A Form 3 is filed once when someone first becomes an insider and lists starting holdings. A Form 5 is an annual catch-up for certain small or exempt transactions. Form 4 is the timely one - it is what you use to see recent activity.

Each filing reports the insider's name and relationship to the issuer, the transaction date, a one-letter transaction code, the number of shares, the price (when applicable), whether the holding is direct or indirect, and the insider's beneficial ownership after the transaction.

Read the post-transaction holdings carefully. A large buy that barely changes a tiny stake is a different story from a buy that meaningfully increases an already large position. Stake impact is one of the factors in the Greediness Score.

A practical filter: start with code P purchases by senior roles, then check whether other insiders of the same company bought in the same window. Compensation mechanics (A/M/F) can look like buying activity if you only skim share counts.

Insiders sell for many neutral reasons. There is essentially one economic reason to spend personal cash on open-market shares: they expect the stock to be worth more than the price they paid. Academic work on Form 4 data has repeatedly found that open-market purchases - especially by senior executives - carry more information than sales.

That does not make a code P filing a buy recommendation. It makes it a better research prioritization cue than a routine option exercise or tax withholding.

Greedy Insider ingests Form 4s from SEC EDGAR and rates each filing's structural conviction from 0 to 100 with the Greediness Score. Use the score to decide which filings to read first, then open the primary document and verify codes, share counts, and holdings.

For a worked example of coordinated open-market buying, see the NVIDIA director cluster case study. For the short definitional primer, see the Learn guide. For the full map of Form 4, Congress, and 13D filings, start with the insider trading pillar.

A Form 4 does not disclose the insider's private thesis, does not prove non-public information was used, and does not forecast returns. Late or amended filings happen. Data can be incomplete. Treat every Form 4 as a structured disclosure to verify, not as a tip.