SEC insider transaction codes — full reference
Every line on a Form 4 carries a one-letter transaction code describing what happened. The most informative are P (an open-market purchase) and S (an open-market sale). Here is the full set.
| Code | Meaning | Signal |
|---|---|---|
| P | Open-market or private purchase | Strong — insider buying with own money |
| S | Open-market or private sale | Mixed — may be planned or for liquidity |
| A | Grant, award, or other acquisition from the company | Compensation, not conviction |
| M | Exercise or conversion of a derivative security | Mechanical — options becoming shares |
| F | Shares withheld or delivered to pay an exercise price or taxes | Mechanical — tax/cost settlement |
| G | Bona fide gift | Neutral — transfer, not a market trade |
| X | Exercise of an in-the-money derivative | Mechanical |
| C | Conversion of a derivative security | Mechanical |
| D | Disposition to the issuer | Buyback / settlement |
| W | Acquisition or disposition by will or inheritance | Neutral |
| I | Discretionary transaction (e.g., within a benefit plan) | Usually mechanical |
| J | Other (explained in a footnote) | Read the footnote |
| U | Disposition pursuant to a tender of shares | Event-driven (merger/tender) |
Open-market vs everything else
Only P and S represent an insider choosing to buy or sell in the market. A, M, F, C, and X are the plumbing of equity compensation — options vesting, being exercised, and shares withheld for tax. They move share counts without expressing a view.
When to read the footnotes
Code J means "other," and any line can carry a footnote that changes its meaning — a weighted-average price across multiple trades, a transfer between related accounts, or the terms of a 10b5-1 plan. When a number looks surprising, the footnote usually explains it.
SEC Notifier builds its net-flow, leaderboard, cluster, and network signals from open-market common-stock activity (P and S, non-derivative) only, so grants, exercises, and tax withholding don’t pollute the read.