If you spend any time reading SEC Form 4 filings, you will eventually notice a footnote that appears on many insider sale transactions. It says, in some variation: "This sale was made pursuant to a Rule 10b5-1 trading plan adopted on [date]."
This footnote matters. It changes the interpretation of the transaction entirely — and understanding what it means is essential for anyone trying to extract useful signals from insider trading data.
What Is Rule 10b5-1?
Rule 10b5-1 is an SEC regulation adopted in 2000 that created a safe harbor for corporate insiders who want to buy or sell shares in their own company without running into insider trading liability.
The core problem it was designed to solve is straightforward. Corporate executives are often in possession of material non-public information about their company — not because they are doing anything wrong, but because that is the nature of their role. They know about earnings before they are announced, strategic decisions before they are public, and competitive developments before they appear in press releases.
This creates a practical dilemma. If insiders can only trade when they are certain they possess no material non-public information, they may find that there are very few windows in which it is actually safe to sell shares — and selling shares is often necessary for legitimate reasons like diversification, estate planning, or covering tax liabilities from equity compensation.
Rule 10b5-1 solved this by allowing insiders to establish pre-scheduled trading plans during a period when they are not in possession of material non-public information. Once the plan is in place, trades execute automatically on a predetermined schedule, regardless of what the insider knows at the time of execution.
How a 10b5-1 Plan Works
The mechanics of a 10b5-1 plan are relatively straightforward.
Step 1: The insider adopts the plan. During an open trading window — typically shortly after an earnings release when the insider is not in possession of non-public information — the insider establishes a written plan with their broker. The plan specifies one of three things:
- A fixed number of shares to be sold at specific dates
- A formula or algorithm for determining when and how much to sell
- A delegation of decision-making authority to the broker, who makes trades based on predetermined criteria
Step 2: A mandatory waiting period. Under rules tightened by the SEC in 2023, insiders must observe a waiting period before the first trade under the plan can execute — 90 days for most insiders, and 120 days for officers and directors.
Step 3: Trades execute automatically. Once the plan is active, trades happen according to the schedule regardless of what the insider knows at the time. The insider has no discretion over individual trade timing or sizing.
Step 4: Disclosure on Form 4. When a trade executes under a 10b5-1 plan, it is disclosed on Form 4 like any other insider transaction — but with a footnote indicating the plan's existence and the date it was adopted.
Why 10b5-1 Plans Matter for Interpreting Insider Sales
The practical implication for investors reading Form 4 data is significant. When a sale is made under a 10b5-1 plan, the timing of the decision to sell was made weeks or months before the transaction actually occurred — during a period when the insider was not in possession of material non-public information.
This means the transaction carries much less directional information than a discretionary open-market sale. The insider is not looking at the company's current situation and deciding it is a good time to sell. They are executing a plan they made in the past.
In contrast, a discretionary open-market sale — an S-coded transaction with no 10b5-1 footnote — reflects a current decision made by an insider who may or may not have additional context about the company's near-term prospects. It is this type of transaction, combined with the situational factors described in our guide to insider buying vs selling, that carries more potential signal value.
The Controversy Around 10b5-1 Plans
Despite the safe harbor intent, 10b5-1 plans have attracted significant academic and regulatory scrutiny — because the evidence suggests they have been used in ways that undermine their stated purpose.
The adoption timing problem
Before the SEC's 2023 rule changes, there was no mandatory waiting period between when a plan was adopted and when the first trade could execute. An insider could adopt a plan on Monday and have shares sold by Friday.
This created a significant loophole. An executive aware of an impending negative announcement could adopt a 10b5-1 plan and immediately sell shares — claiming the protection of the safe harbor while effectively trading on non-public information. Academic research found that first trades under 10b5-1 plans adopted before earnings releases significantly underperformed in the subsequent weeks, suggesting the plans were sometimes used to front-run bad news.
Multiple overlapping plans
Prior to 2023, insiders could maintain multiple 10b5-1 plans simultaneously and selectively execute the one most advantageous given current market conditions. This flexibility further eroded the safe harbor's protective purpose.
Single-trade plans
Some insiders used what became known as "single-trade" 10b5-1 plans — essentially, a plan with only one trade scheduled, executed immediately after adoption. This provided almost no buffering between the decision to sell and the transaction itself.
The 2023 SEC reforms
In response to these concerns, the SEC implemented significant rule changes in 2023:
- Mandatory cooling-off periods of 90 days (or the next earnings release, whichever comes later) for most insiders, and 120 days for officers and directors
- Prohibition on single-trade plans being used more than once per twelve-month period
- Restrictions on overlapping plans
- Enhanced disclosure requiring the disclosure of plan adoption dates on Form 4
These changes significantly tightened the safe harbor, though critics argue they do not go far enough.
How to Identify 10b5-1 Sales in Form 4 Filings
On Form 4, sales made under a 10b5-1 plan are identified in two ways:
- Table I, column 6 — a checkbox indicating whether the transaction was made pursuant to a Rule 10b5-1(c) plan
- Footnotes section — typically containing language such as "This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on [date]"
If you see a sale without either of these indicators, it is a discretionary sale — and more likely to carry directional information.
Our insider trades dashboard distinguishes between plan-based and discretionary sales in the transaction type filter, so you can choose to focus on whichever type is more relevant to your research.
10b5-1 Plans and Purchases
While 10b5-1 plans are most commonly associated with insider selling, they can also be used for purchases. A purchase made under a pre-scheduled buying plan is less informative than a discretionary open-market buy for the same reason — the timing of the decision was made in the past, not in response to current conditions.
In practice, scheduled purchase plans are much rarer than scheduled sale plans. Most executives have ongoing diversification needs that make pre-scheduled selling useful, while scheduled buying is less common and often reflects a structured wealth-building commitment rather than a real-time valuation judgment.
When you see a discretionary purchase — a code-P transaction with no 10b5-1 footnote — you are looking at an insider making a current, active decision to add to their position. This is the signal worth paying attention to.
Practical Implications for Your Research
A few specific things to check when reviewing any insider sale on Form 4:
Is there a 10b5-1 footnote? If yes, the sale carries less informational content. The decision to sell was made in the past, during a defined trading window, for planning purposes.
When was the plan adopted? Post-2023 plans require a cooling-off period, making them somewhat more robust. Pre-2023 plans adopted without a cooling-off period are more suspect, particularly if the adoption date was shortly before the sale.
How large is the sale relative to the insider's total holdings? A plan-based sale of 5% of an insider's position is routine portfolio management. A plan-based sale of 80% of their position warrants closer examination, even accounting for the scheduled nature.
Are there any discretionary sales happening concurrently? If some insiders are selling under 10b5-1 plans while others are making discretionary sales without plan footnotes, the discretionary sellers deserve more attention.
Summary
A 10b5-1 trading plan is a pre-scheduled arrangement that allows corporate insiders to buy or sell shares without incurring insider trading liability, because the trade parameters were established during a period when the insider was not in possession of material non-public information.
For investors interpreting Form 4 filings, the presence of a 10b5-1 footnote on a sale transaction significantly reduces its directional signal value. The insider is executing a previously scheduled plan, not making a current judgment about the stock.
Discretionary sales — S-coded transactions without a plan footnote — carry more potential information, though interpreting them still requires context. Discretionary open-market purchases — P-coded transactions, with or without a plan — remain the most reliable and consistently informative signal in insider trading data.