10b5-1 Plan Sales vs Discretionary: How to Read Form 4

The single most common editorial mistake in insider trading commentary is framing a Rule 10b5-1 plan sale as a discretionary conviction signal. When a major news outlet writes "CEO dumps $X million in stock," half the time the underlying transaction was a pre-scheduled distribution from a 10b5-1 plan adopted six to twelve months earlier — meaning the CEO had no discretion over the timing, the price, or the share count at the moment of the sale. Reading those sales as "the CEO thinks the stock is overvalued" is exactly the kind of mistake that produces bad investment decisions.

This guide explains what a Rule 10b5-1 plan is, how to spot a plan-driven sale in the Form 4 record, and where the genuine discretionary signal in insider activity actually lives. The goal is to make you a better reader of insider transaction feeds, not to summarize SEC regulation.

What Is a Rule 10b5-1 Plan?

Rule 10b5-1, adopted by the SEC in 2000 and substantively amended in 2022, creates a safe harbor for corporate insiders to trade their own company's stock without violating insider-trading prohibitions. The mechanism: the insider adopts a written plan at a time when they are not in possession of material non-public information (MNPI), and the plan specifies in advance the share count, price, or formula for future transactions. The insider then has no discretion at the moment of execution. The broker runs the plan on schedule.

The 2022 amendments added a 90-day cooling-off period between plan adoption and the first trade, a 120-day cooling-off period for directors and officers, and a requirement that the plan be entered into in good faith. Multiple overlapping plans are now restricted, and one plan per insider per 12-month period is the new default.

The practical effect: when you see a CEO selling shares in March, the relevant disclosure window is the plan adoption date — which might be the prior September or October. The sale itself is mechanical execution, not a March view.

How to Spot a 10b5-1 Plan Sale on Form 4

Form 4 filings have a specific checkbox indicating whether the transaction was made pursuant to a 10b5-1 plan. The checkbox is in the "Explanation of Responses" or footnote section, with language like:

"The shares reported on this Form 4 were sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on [date]."

Three additional signatures of 10b5-1 plan-driven selling — visible from the Form 4 stream even without reading the footnote — are worth knowing.

Signature 1: Regular share lot sizes across consecutive sessions

When a single transaction breaks into multiple lots executed at different prices on the same day, that is the signature of a broker working a parent order through the trading session. A plan-driven sale typically has consistent share counts across multiple sessions in a tight window (35,000-65,000 shares per session is a common range for large-cap insiders), with the broker filling the parent order across the order book.

The dollar value floats with the share price, but the share count stays anchored to the plan. If you see an insider selling exactly 50,000 shares on five different days at five different prices, that is mechanical execution of a 50K-per-session schedule, not five discretionary decisions.

Signature 2: No clustering around earnings dates or news events

Discretionary insider selling clusters around earnings releases (after the earnings blackout opens), M&A announcements, analyst day events, and other catalysts the insider's information advantage might apply to. Plan-driven selling explicitly ignores these dates — the plan executes on its schedule regardless of whether the company has just beaten earnings or guided down. If a CEO is selling at the same cadence in the week before earnings as in the week after, the trades are plan-driven.

Signature 3: Cadence regularity over months and quarters

Plan-driven distributions follow a calendar. Weekly, biweekly, monthly, quarterly — the cadence is consistent. Discretionary selling is bursty: nothing for two months, then a large block sale in a one-week window, then nothing for three months. If an insider's Form 4 stream shows even-weighted distributions for six consecutive months, you can assume a plan is running.

The Forms 4 Codes That Are Never Discretionary

Beyond 10b5-1 plans, several Form 4 transaction codes describe compensatory or administrative transactions that should never be read as discretionary conviction signals:

Code	Meaning	Why it's not discretionary
F	Tax withholding at vesting	Mechanically forced — the issuer or broker withholds shares to cover income tax on vested RSUs. The insider does not choose to sell; the IRS effectively does.
M	Option exercise	Converting options into shares is a balance-sheet change, not a market trade. An exercise often does not produce any market activity in the underlying stock.
A	Award / grant	The insider received compensation in the form of RSUs, options, or shares. No view on the stock is implied.
G	Gift	A transfer to a family member, foundation, or trust. Not a market signal; the recipient may or may not eventually sell.
C	Conversion	Converting one security class to another — typically a structural change, not a directional one.
D	Disposition (non-market)	Usually administrative — internal transfers, plan rebalancing, ESPP unwinds.

Of the Form 4 transaction codes, only S (open-market sale) and P (open-market purchase) can be discretionary — and even S requires a check on the 10b5-1 plan footnote before assuming discretion.

Where Discretionary Insider Signal Actually Lives

If most insider selling is plan-driven, where is the genuine signal? Three places:

1. Open-market purchases (code P)

Insiders buying their own stock with their own money in the open market is, in practice, almost always discretionary. Corporate compensation plans grant shares; they do not require insiders to buy more shares with after-tax cash. When a CFO writes a six-figure check to buy more of the company's stock through their brokerage account, that is a real conviction signal — and one that traditional databases historically under-surface.

2. Plan adoption / amendment events

The act of adopting a 10b5-1 plan, or amending an existing plan, is itself disclosed and is itself a signal. An insider who has not had a plan in years adopting a new one signals intent to sell over the coming year. An insider who terminates a plan signals a decision to pause selling — often because new MNPI is anticipated. The 2022 amendments require disclosure of plan adoption and termination in 10-Q and 10-K filings, making this signal much more accessible than it was pre-amendment.

3. Pattern deviations from established cadence

When an insider with a long-running 10b5-1 plan suddenly increases share lot sizes by 3x, or shortens the cadence from quarterly to monthly, that is a deviation worth investigating. The plan adoption mechanism is meant to remove discretion at execution time, but the adoption itself reflects intent. A material upsizing typically requires a new plan, which means a new adoption date — and a new look at what the insider expected to know over the plan window.

How to Apply This in Practice

When you read about a CEO or founder selling stock, run the three-question check before drawing a conclusion:

1. What does the Form 4 footnote say about a 10b5-1 plan? If the footnote references a plan, the sale is plan-driven. Frame the sale as "executed pursuant to a Rule 10b5-1 plan adopted [date]," not as "CEO sells X dollars of stock."
2. What is the transaction code? S/P only. M, F, A, G, C, D are not market signals.
3. What is the historical cadence? If the recent transactions match a 6-12 month rolling pattern, the plan is intact and the headline is mechanical. If the cadence has deviated materially, investigate the why.

We apply this framework consistently across our coverage. See the Charles Schwab cadence read and the Joseph Mansueto plan analysis for recent worked examples of how plan-driven sales should be framed in editorial context.

The Bigger Picture

Reading insider activity well is a discipline of separating mechanical disclosure from genuine information. Most disclosure is mechanical: compensation grants, tax withholding, plan execution. The genuine information signal is concentrated in a small set of events — open-market buys, plan adoption / termination, and material deviations from established cadence. Building the habit of running the three-question check before drawing conclusions will materially upgrade how much actual signal you extract from any insider transaction feed.

For real-time insider activity with the active-only filter applied, the smart-money signal feed aggregates the relevant subset across the platform. SEC documentation on Rule 10b5-1 plan requirements, including the 2022 amendment package, is available on the SEC's Rule 10b5-1 final rule release.