The Short-Swing Profit Rule (Section 16(b))

Section 16(b) of the Securities Exchange Act requires corporate insiders to hand back to the company any profit realized from a purchase and sale of company stock within a six-month window. It is a strict-liability rule: no proof of inside information, intent, or even awareness is required. If the trades match, the profit is disgorged.

How matching works

Courts match the lowest purchase price against the highest sale price within any six-month period to maximize the recoverable profit - even if the insider's actual sequence of trades lost money overall. Any shareholder can sue derivatively to enforce it, and a specialist plaintiffs' bar scans Form 4 filings for matchable pairs, so enforcement is close to automatic.

Who is covered, and what's 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).

Why this matters for reading insider signals

The rule quietly shapes the data you see on Form 4:

• Insiders cannot day-trade their own stock. An open-market purchase locks the insider out of profitable selling for six months - so a code-P buy is, structurally, a commitment of at least six months. That is part of why insider buys carry signal.
• Sales right after buys are rare - and when you do see a quick round-trip on a Form 4, it usually involves exempt compensation transactions, not two open-market legs.
• 10% owners time their exits around the threshold, selling down in tranches - context worth knowing when reading insider selling by large holders.

This article is informational and is not legal or investment advice.