10b5-1 Plans Explained: Why Insider Selling Isn’t Always Bearish

Open a financial news site any day of the week and you'll find a headline roughly like “[Company] CEO sells $20M in stock.” The implied reading is that an insider with privileged information is unloading. Sometimes that's true. Usually, it isn't.

The reason is Rule 10b5-1, an SEC regulation finalized in 2000 that quietly changed how almost every public-company executive sells stock. Once you understand the rule, the question to ask about an insider sale stops being “why are they selling now?” and becomes “when did they decide to sell?”

What Rule 10b5-1 actually is

Rule 10b5-1 of the Securities Exchange Act creates an affirmative defense against insider-trading allegations. The defense is available to anyone who, while not in possession of material non-public information (MNPI), commits in writing to a future trading plan that specifies what to trade, when, and at what price.

Concretely, a 10b5-1 plan can lock in any of the following at the time of adoption:

A fixed share count to sell on a fixed date (e.g., 5,000 shares on the first trading day of each quarter).
A formula keyed to price (e.g., sell 2,000 shares any day the closing price exceeds $150).
A schedule delegating execution to a broker, with no further insider involvement.

Once the plan is in force, the insider hands over control. The trades execute by the plan's terms regardless of what the insider learns about the company in the interim. That separation of decision (made when the insider was not aware of material non-public information) from execution (which happens automatically later) is what makes a plan sale defensible — and what makes it informationally weak as a signal.

Why executives use them

Three structural reasons:

Affirmative defense. The plan's existence is what protects the executive if an executed trade later coincides with material news. Without one, every sale by an insider near earnings or product news is a litigation target.
Diversification under regulatory friction. Most executives are heavily concentrated in their employer's equity. A plan lets them methodically diversify without having to time blackout windows or pre-clear each trade.
Liquidity for tax events. RSU vesting schedules trigger predictable tax bills. A plan that sells just enough shares to cover those bills is administratively simple and politically defensible.

The 2023 amendments and what they changed

In December 2022 the SEC adopted significant amendments to Rule 10b5-1 that took effect in early 2023. Three pieces matter for reading filings today:

Mandatory cooling-off periods. Officers and directors must wait 90 days (or two business days after disclosing the next quarterly earnings, whichever is later) between adopting a plan and the first trade under it. Other insiders wait 30 days. This was directly aimed at the practice of adopting a plan and selling almost immediately under its cover.
Single-trade plan limits. An insider can only adopt one single-trade 10b5-1 plan per 12-month period. Previously, layered single-trade plans were a workaround for the spirit of the rule.
Disclosure on Form 4 and in 10-Qs. Form 4 now has a checkbox (Item 16) indicating whether a transaction was made under a 10b5-1 plan, and companies must disclose plan adoptions and terminations quarterly. This made plan-vs-discretionary trades visible in the data for the first time.

For data consumers like Watch4Insider, the practical implication is that the signal has become readable. Before 2023, you had to infer whether a sale was a plan sale from indirect evidence (regular cadence, suspiciously round share counts). Now the filing tells you.

How to read a sell once you know about plans

Two questions to apply to any Form 4 S-coded transaction:

1. Is the “adopted under a 10b5-1 plan” box checked?

If yes, the sell is execution of a decision the insider made — and committed to in writing — months ago. It tells you very little about what they think today. Bucket it as low-signal.

2. If no, when did the insider sell last time?

Discretionary sells by an insider who rarely sells are more informative than the same insider's 17th routine sale of the year. The first deserves a read; the rest are likely diversification.

On Watch4Insider, the underlying transactions for any name are visible on the ticker page — for example, /ticker/AAPL shows the 90-day cadence of buys and sells per insider. A pattern of sells every two weeks is almost always a plan; an irregular sell after a year of silence is the kind worth looking at directly via the linked Form 4 detail page (each row links to its own filing).

Why buys are different

Although 10b5-1 plans can technically schedule purchases, almost nobody uses them for buys. The reasons are practical:

Insiders rarely want to commit to buying their own stock on a fixed schedule — they'd rather choose when to put capital in.
The downside of a plan-driven buy at a high is unbounded; the downside of a plan-driven sell at a low is just opportunity cost.
Buys are rare enough that the legal exposure from a single discretionary buy is manageable.

The result: almost every Form 4 P (purchase) is discretionary, which is part of why P transactions carry the signal weight they do — and why the cluster-buy framing concentrates on buys rather than sells. A cluster of plan sells means nothing. A cluster of discretionary buys means quite a lot.

When plan sells do signal something

Even with the plan disclosed, two patterns are still worth a second look:

A plan adopted unusually recently before a large sale. The 2023 cooling-off period mitigated the worst version of this, but freshly-adopted plans that happen to coincide with the executive's most concentrated holdings window are still worth noting.
Plan terminations followed by accelerated sales. The amendments require quarterly disclosure of plan terminations. When you see one, the question is what changed.

Bottom line

The intuitive read of an insider sale — “they know something we don't, and they're cashing out” — was a reasonable model in 1985. After two decades of 10b5-1 plan adoption and the 2023 disclosure amendments, the better prior on any given executive sale is that it's a pre-scheduled mechanical transaction with limited information content. Treat them as the baseline and reserve attention for the exceptions: discretionary buys, discretionary sells outside the usual cadence, and the (rare) plan transactions whose adoption timing looks engineered.

That's also why Watch4Insider's default screeners and the sentiment report emphasize buys over sells, and why the large-purchases report is the single most-read page in the Reports section. Reading sales requires context; reading purchases — most of the time — does not.