Insider Selling: What It Actually Tells You

Why insider sales are noisier than insider purchases, which sales are routine, and the patterns (clusters, size, timing) that deserve a closer look.

Insider purchases get the headlines, but insider sales are far more common. Executives are paid in stock, so they sell it. The challenge is separating the routine from the revealing.

Why most sales are routine

Insiders sell for reasons that have nothing to do with the company's prospects:

• Taxes. Vesting stock creates a tax bill. Some is covered by shares withheld (code F, not a market sale), some by selling.
• Diversification. Many executives have most of their wealth in one stock.
• Big purchases and life events, such as a house, a divorce or education.
• Scheduled selling. Many sales follow a Rule 10b5-1 plan set months earlier.
• Option exercises followed by same-day sales.

Academic work on US insider trading (Jeng, Metrick and Zeckhauser) found that insider purchases earned significant abnormal returns while sales did not. That is consistent with the intuition: a buy has one motive, a sale has many.

Sales that deserve a second look

None of these is proof of anything, but they raise the odds that a sale is a real decision:

1. Cluster selling. Several insiders selling the same company in a short window, mirroring the logic of cluster buying.
2. Large share of holdings. Selling a big fraction of a stake, not 2%.
3. Unplanned sales. An open-market sale with no 10b5-1 checkbox, made at a moment of the insider's choosing.
4. Senior roles. A CEO or CFO selling is more informative than a junior officer.
5. A change in behaviour. Someone who rarely sold suddenly selling heavily.
6. Sales right after good news are usually benign. Sales before a surprise are what regulators look for, and you will never prove that from one filing.

What to check in the Form 4

Open the Form 4 and read: the transaction code (S for a market sale, F for tax withholding), the 10b5-1 checkbox, the shares owned afterwards, and the footnotes. Then compare with the previous twelve months for that person.

How to use it

Treat insider selling as context, not a sell signal. It becomes interesting in combination: heavy unplanned selling by several senior people, while funds are reducing, is a better reason to look closer than any single filing.

Bourse shows only genuine open-market buys (P) and sells (S), so tax withholdings and awards do not pollute the picture.

Bourse provides financial data and editorial information, parts of which are generated by AI. This page is for general education only. It is not personalised investment advice or a recommendation to buy or sell any financial instrument. Make your own decisions.