The short-swing profit rule (Section 16(b))
By InsiderAlpha · Published · Updated
Written from SEC primary filings, with every rule cited inline. Editorial standards.
Section 16(b) of the Securities Exchange Act requires corporate insiders to pay the company any profit realized from a purchase and sale of company stock within a six-month window. It is strict liability: nobody has to show inside information, intent, or even awareness. If the trades match, the profit goes back.
How matching works
Courts match the lowest purchase price against the highest sale price within any six-month period, which maximizes the recoverable profit. An insider can owe money even when their actual sequence of trades lost money overall. Any shareholder can sue on the company's behalf to enforce the rule, and a specialist plaintiffs' bar scans Form 4 filings for pairs that match, so a matched trade is likely to be noticed.
Follow insider buying without reading every filing
We read every Form 4 as it is filed and rank the insider purchases worth a look into a daily trading plan, so you do not have to open each filing yourself.
Free by email: highlights from the previous session's daily trading plan each market morning, plus a Friday roundup of the week's insider buying.
Basic reads each plan from the previous close, before the open. Compare plans or see the daily plan.
Who is covered, and what is exempt
- Covered: directors, Section 16 officers, and 10% owners (for 10% owners, both trades must occur while above the threshold).
- Exempt under Rule 16b-3: most compensation-plan transactions with the issuer - option grants, RSU vesting, tax-withholding dispositions (codes A, M, F) - when approved by the board.
- Not exempt: ordinary open-market purchases (code P) and sales (code S).
What it means for reading Form 4s
- Insiders do not day-trade their own stock. An insider who buys on the open market and sells higher within six months hands the gain to the company, so a code-P purchase is hard to flip quickly. It is not a lockup: the rule recovers profit, it does not block a sale. Are insider buys bullish? covers why purchases get read closely.
- Quick round trips are uncommon. When a Form 4 does show one, it usually involves exempt compensation transactions rather than two open-market trades.
- For a 10% owner, the threshold matters. The rule only reaches trades made while the holder is above 10%, so note where a large holder stood before and after each sale when reading insider selling.
This article is informational and is not legal or investment advice.