Reading 10b5-1 Plan Footnotes on Form 4 Filings

The single most common error in reading insider trading data is treating every CEO sale as a discretionary view change. The signal — and the lawsuit risk for any reader-turned-writer who frames it wrong — sits in a small footnote that the Form 4 either has or doesn't have: the Rule 10b5-1 plan adoption disclosure.

What Rule 10b5-1 actually is

Rule 10b5-1 is an SEC safe harbor adopted in 2000 and materially amended in December 2022. It lets corporate insiders set up a written trading plan in advance — typically with a broker — that specifies when, how much, and at what price stock will be bought or sold. Once the plan is adopted (during a window when the insider has no material non-public information), the trades execute mechanically. The insider does not make the discretionary decision to sell on the day the trade clears; the plan does.

The 2022 amendments added two requirements that affect how Form 4 disclosures look today:

• Mandatory cooling-off period: 90 days for officers and directors, or until the next earnings release if later. Plans adopted during a closed window cannot trade for that period.
• Mandatory plan adoption box on Form 4: A new check box and footnote requirement starting April 1, 2023 — every Form 4 reporting a transaction made under a 10b5-1 plan must explicitly indicate it.

Where to look on a Form 4

Open any post-April-2023 Form 4 on EDGAR and look for two specific pieces:

1. The check box at the top of Table I or Table II labeled "Transaction(s) made pursuant to a Rule 10b5-1 trading plan." If checked, the transactions on that line were plan-driven.
2. The plan adoption date footnote, typically referenced as "(1)" or "(2)" next to the transaction line. The footnote text usually reads: "These shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on [DATE]."

If neither the check box is marked nor a plan footnote appears, the transaction was discretionary. That distinction is the most important single fact in the filing.

Why discretionary vs plan-driven matters

A discretionary sale is a real-time view: the insider chose to sell at this price, on this day, knowing what they knew. That is the foundation of every "insider selling = bearish signal" thesis.

A plan-driven sale is a calendar event. The insider committed weeks or months earlier to sell N shares whenever the plan window opened, regardless of price or news. Reading a plan-driven sale as a bearish view change is the most common framing error in financial journalism — and the SEC has prosecuted insiders specifically for using plans incorrectly to mask discretionary trading.

The visual signatures that suggest plan-driven trading

Even before you read the footnote, certain transaction patterns are highly suggestive of a 10b5-1 plan:

• Tightly clustered prices in same-day sequences — a sale broken into 5-10 tranches walking from $90.00 to $91.86 over a single trading day usually indicates a VWAP or trailing-sell algorithm running inside a plan window.
• Identical share lot sizes month after month — recurring sales of exactly 50,000 or 100,000 shares on the same day each month is mechanical, not opinionated.
• Consistent timing relative to earnings releases — sales that always clear 2-4 trading days after earnings are plan-driven; the post-earnings window is the standard time when 10b5-1 plans open. Discretionary sellers cluster less predictably.
• Avoidance of pre-earnings windows — a Form 4 that consistently shows zero activity in the 30 days before each earnings release is consistent with the company's blackout period; plan-driven trading respects blackouts mechanically.

What the platform's data layer tells you

Within 13F Insight's data, you can verify the plan-driven thesis by looking at the full transaction history on an insider's profile page (e.g. the Anthony Wood Roku profile or the Charles Schwab profile) and scanning for:

• Repeating monthly cadence in the transaction date column
• Same lot sizes (e.g., 50,000 shares) appearing across multiple months
• Price walks within each multi-tranche day rather than single block prints
• The "S" code (open-market sale) appearing in clusters — five S transactions on a single date is almost always a plan tranche

When to be cautious about discretionary framing

Even when the Form 4 footnote does NOT mention a 10b5-1 plan, that does not always mean the sale was a bearish view change. Other common non-discretionary patterns include:

• F (tax withholding) at RSU vest — the company forces the share withholding to cover income tax on a vested grant. Mechanical, not a view.
• M (option exercise) — converting compensation, not selling on conviction. Often paired with same-day S sales for cash settlement.
• G (gift) — the shares left the insider's account but went to a recipient (foundation, family member, charity), not the open market.
• C (conversion) — common for dual-class founders who convert Class B to Class A before selling. Usually paired with an S the same day; does not change the underlying conviction read.

A practical reading checklist

Before writing or sharing a take on an insider Form 4, run through:

1. Open the Form 4 on EDGAR. Confirm the transaction code (S vs M vs F vs G vs C).
2. Check the 10b5-1 plan adoption box and footnote. Note the plan adoption date if present.
3. Open the insider's full transaction history on a platform like 13F Insight's insider data hub. Look for monthly cadence, repeating lot sizes, and price walks.
4. Cross-check Table I (Class A common) against Table II (derivative / Class B / indirect). The "shares owned after" zero on Table I is meaningless if Table II shows millions still held.
5. Place the sale relative to the company's earnings calendar. Sales 2-4 days after a release are plan-driven; sales the trading day before a release are nearly impossible (blackout).

Insider trading data is rich, but most of the richness comes from distinguishing the shape of the trade — not its size. A $50 million plan-driven sale is a non-event. A $5 million discretionary sale by a CEO 48 hours before a guidance cut is a serious signal. The Rule 10b5-1 footnote is what tells you which is which.

For more on reading 13F and Form 4 filings, see the full Learn library. The SEC's rule text is publicly available at SEC Final Rule 33-11138 (2022 amendments to Rule 10b5-1).