What Is Insider Buying? Definition and Example
What counts as insider buying, how it is reported on Form 4, and what research says about when it is a useful signal.
GlossaryGlossary
What Is SEC Form 4? Definition and Example
What a Form 4 filing is, who has to file it and how fast, and how to read the transaction codes without over-reading them.
Key takeaways
- A Form 4 is the SEC filing a company insider uses to report a trade in the company’s securities, generally within two business days of the transaction.
- Insiders are officers, directors and holders of more than 10% of a class of the company’s securities.
- Each trade carries a code. P is an open-market or private purchase and S is a sale; many other codes are grants, option exercises or tax withholding.
- Insiders sell for many reasons, such as taxes or diversification, so a single sale says little on its own.
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What is a Form 4?
Form 4 is a public statement of a change in an insider’s ownership. Per the SEC’s investor bulletin on Forms 3, 4 and 5, it must be filed within two business days after the transaction and shows the amount bought or sold and the price per share. Filings are free to read on the SEC’s EDGAR database.
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How do Forms 3, 4 and 5 fit together?
| Form | When it is filed | What it shows |
|---|---|---|
| Form 3 | Within 10 days of becoming an insider | Starting ownership |
| Form 4 | Within two business days of a trade | Each purchase, sale, grant or exercise |
| Form 5 | Within 45 days after fiscal year end, if needed | Transactions not reported earlier |
Worked example: reading the codes
Illustrative: a chief financial officer files three Form 4s in one quarter.
| Code | Meaning | How much it tells you |
|---|---|---|
| A | Grant or award from the company | Little: it is pay, not a decision |
| F | Shares withheld to pay tax or exercise price | Little: usually automatic |
| P | Purchase on an exchange or from another person | More: the insider chose to buy with own money |
Why it matters for a self‑directed investor
Open-market purchases by several insiders are among the few public signals of what management thinks of its own stock. See insider buying and insider selling, and the guide how to track smart money.
Common mistakes
- Counting grants (A) and tax withholding (F) as buying or selling decisions.
- Reading planned sales as bearish. Pre-arranged Rule 10b5-1 plans sell on a schedule.
- Confusing Form 4 with a 13F filing, which reports fund holdings each quarter.
See insider activity with Exent
- Open a stock in Stocks Radar to see insider buying and selling next to congress and 13F activity.
- Portfolio Analysis shows analyst and insider activity on the holdings you upload.
Frequently asked questions
Generally two business days after the transaction. A few transactions can be reported later on Form 5.
P means a purchase of securities on an exchange or from another person. It is the code most investors watch, because the insider chose to buy.
On the SEC’s EDGAR database. Many stock research sites also republish them.
Not by itself. The SEC notes that insiders sell for many reasons, including liquidity and diversification.
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Educational content, not investment advice. Examples are illustrative; past performance does not guarantee future results.