What is a Form 4?
A Form 4 is the filing an insider must submit within two business days of trading their own company's stock. What is in one, and what actually matters.
A Form 4 is the disclosure a corporate insider must file with the SEC within two business days of buying or selling shares in their own company.
“Insider” has a specific meaning here: an officer, a director, or anyone holding more than 10% of a class of the company’s stock. Not employees generally.
What is actually in one
A Form 4 is short — usually one page of tables. The parts that matter:
| Field | What it tells you |
|---|---|
| Table I | Non-derivative transactions: ordinary buys and sells of stock |
| Table II | Derivatives: options, warrants, convertibles |
| Transaction code | A one-letter code. P = open-market purchase, S = open-market sale, M = option exercise, A = grant or award, G = gift |
| Amount and price | Shares transacted and price per share |
| Shares owned following | What they hold afterwards — the number that turns a sale into a story |
| Footnotes | Where a 10b5-1 plan is disclosed, if there is one |
The three things worth checking
1. The transaction code. An S is someone choosing to sell on the open
market. An M followed by an S is an option exercise-and-sell, which is
routine compensation behaviour and means much less. Treating those as the same
thing is the most common mistake people make reading these.
2. What proportion went. Selling 5,000 shares means nothing without knowing whether they held 20,000 or 2,000,000. “Shares owned following transaction” gives you the denominator. A sale of most of a position is a different event from trimming.
3. Whether a 10b5-1 plan is disclosed. A Rule 10b5-1 plan is a pre-arranged trading schedule set up in advance, which gives the insider an affirmative defence against insider-trading allegations. It is disclosed in a footnote. Since 2023, amended rules impose cooling-off periods before trades under a new plan can begin. A sale under a long-standing plan is weak evidence of anything. A sale with no plan, at an unusual size, before material news, is why these filings are worth reading.
What a Form 4 does not prove
It does not establish intent or wrongdoing. Executives sell for tuition, divorces, tax bills, and diversification. What the filing establishes is narrow and factual: this person sold this much on this date, and this is what they had left.
Everything beyond that is inference, and should be labelled as such.
Where to find them
Search a company on SEC EDGAR
and filter the form type to 4. Or browse the
latest Form 4 filings across all companies
— that feed updates continuously through the trading day, and scrolling it for
ten minutes is the fastest way to get a feel for what normal looks like.
The same document elsewhere
| Country | Equivalent |
|---|---|
| United States | Form 4, filed with the SEC |
| Canada | Insider report, filed on SEDI — within five calendar days |
| United Kingdom | PDMR notification under UK MAR, announced via RNS — within three business days |
The deadlines differ, the substance does not: a person with access to the information is required to tell you when they trade on their own company.