Why insiders sell
Executives are often paid largely in stock, which leaves much of their personal wealth in a single company. Selling some of it is ordinary financial planning. They sell to diversify, to pay income tax on vested shares, to buy a house, to fund a charity or simply on a schedule. That is why sales vastly outnumber purchases: in the 12 months to September 2026, insiders reported about $173.8 billion of open-market sales on Form 4 against about $29.3 billion of purchases, according to SignalX data.
So the question is never "did an insider sell?" It is "was this sale different from the usual?"
How 10b5-1 plans work
A Rule 10b5-1 plan lets an insider set up future trades in advance, at a time when they are not aware of material non-public information. The plan fixes the amount, price or timing, and a broker executes it. Trades made under a qualifying plan give the insider a defense against insider trading claims.
The SEC tightened the rules in December 2022. Officers and directors now face a cooling-off period before any trade under a new or modified plan, they cannot run overlapping plans, single-trade plans are limited to one a year, and every Form 4 now shows whether a trade was made under a plan.
Plan adopted
While not aware of material non-public information
Cooling-off
Officers and directors: 90 to 120 days with no trades
Scheduled sales
Run on autopilot by the broker, each reported on Form 4
months after adoption →
Form 144: the advance notice
Officers, directors and other affiliates who plan to sell more than 5,000 shares or $50,000 worth of stock in a three-month period must file a Form 144 notice before or at the time of the sale. It shows intent, while the Form 4 that follows shows what actually sold, at what price and how many shares the insider still owns.
When selling matters
- Several insiders sell at once, outside a plan. One executive selling says little. Five selling in the same two weeks without the 10b5-1 box checked deserves a look.
- The CEO or CFO sells a large share of their stake. Check the shares owned after the transaction. Selling 5% of a holding is diversification. Selling 60% is a different statement.
- The timing is close to bad news. Sales shortly before a guidance cut, a restatement or a sudden executive departure are the pattern regulators and investors scrutinize most. Our guide to 8-K red flags lists the events to watch.
- A plan is adopted or changed just before a big move. Plan adoptions are disclosed in quarterly reports, and a new plan followed by heavy selling soon after the cooling-off period ends can be informative.
Sales that usually don't
- Code F withholding. Shares withheld to pay tax at vesting are not a market sale.
- Small, regular plan sales. The same number of shares every month or quarter under a 10b5-1 plan was decided long before.
- 10% owner funds rebalancing. A venture fund or private equity firm distributing or selling shares after an IPO is managing its own portfolio, not reacting to inside information.
- Gifts (code G). Transfers to family trusts or charities change who holds the shares, not the insider's view.
Reading sales in SignalX
On the Insiders board, sales sit below the zero line in the weekly flow, the role chart compares officers, directors and 10% owners on the same scale, and the largest sales list leaves fund selling out. For the buying side, see how to spot insider buying signals.