Pillar guide
Insider trading, explained: how to read Form 4, Congress & 13D filings
Insider trading research means reading the public filings that officers, directors, large owners, members of Congress, and activist investors are legally required to submit - and separating the trades that carry information from the routine ones that do not. This guide explains each filing type, the transaction codes that matter, and how Greedy Insider rates every filing from 0 to 100 with the Greediness Score. It is educational research, not investment advice.
What is a SEC Form 4 insider trade?
A Form 4 is the filing a corporate insider - an officer, director, or 10%+ owner - must submit to the SEC within two business days of trading their own company’s stock. It records who traded, the transaction code, the number of shares, the price, and the holdings left afterward, which makes it the most timely public window into what executives do with their own money.
| Code | Meaning | Signal |
|---|---|---|
| P | Open-market purchase with the insider’s own cash | Highest-information code |
| S | Open-market sale | Noisy - many neutral reasons to sell |
| A | Grant or award of stock | Compensation mechanics, not conviction |
| M | Exercise or conversion of a derivative (e.g. options) | Routine, not a cash buy |
| F | Shares withheld to pay taxes | Administrative |
| G | Gift of securities | Not a market transaction |
What is a cluster buy, and why does it matter?
A cluster buy is three or more different insiders of the same company buying its stock within a short window (seven days on this site). One executive buying can be personal; several buying the same name in the same week is much harder to explain away, which is why clustering is one of the highest-weighted factors in the Greediness Score. It is a prioritization cue, not a buy signal.
How do congressional STOCK Act disclosures work?
Under the STOCK Act, members of Congress must report securities transactions on periodic transaction reports. Unlike the two-business-day Form 4 standard, these often surface days or weeks after the trade, so the public tape is delayed by design. Reading them well starts with the clock: compare the trade date to the disclosure date before assigning meaning.
What is a Schedule 13D activist filing?
A Schedule 13D is filed when a person or group crosses 5% beneficial ownership of a company and may seek to influence it. Passive holders generally file the lighter 13G instead, so the more informative events are a 13G-to-13D switch or a 13D amendment that changes the stated purpose. Stake size, sole-versus-shared voting power, and accumulation velocity matter more than the headline percentage.
How does the Greediness Score rate a filing?
The Greediness Score is a transparent 0-100 rating of how much structural conviction a filing shows - built from documented, user-adjustable factors like insider role, cluster activity, trade size versus the person’s own history, and disclosure speed. Scores fall into four bands: Strong (80-100), Moderate (60-79), Mixed (40-59), and Weak (0-39). It describes filing structure and does not predict returns.
Insider trading basics
- What is a SEC Form 4?A Form 4 is the document a company insider (officer, director, or 10%+ owner) must file with the SEC within 2 business days of buying or selling their company’s stock.
- What is a cluster buy?A cluster buy is when three or more different insiders of the same company buy its stock within a short window (7 days on this site).
- The Greediness Score: explainable insider trading scoresThe Greediness Score is a transparent 0-100 rating of how much structural conviction a public filing shows - who traded, how unusually large the trade was for that person, how fast it was disclosed, and who traded alongside them.
Recent analysis
- NVIDIA cluster buy: three directors add after the pullbackThree NVIDIA directors filed open-market purchases within the same week after a multi-session drawdown. We unpack the Form 4 codes, stake impact, and how the Greediness Score weights the cluster.
- STOCK Act disclosure lag: when Congress trades hit the public record lateCongressional stock trades can surface weeks after execution. This case study maps a typical disclosure timeline under the STOCK Act and explains why lag is a first-class scoring input.
- Reading a fresh Schedule 13D: stake size, urgency, and accumulationSchedule 13D filings mark a beneficial owner crossing 5%. This note walks through stake size, purpose clauses, and accumulation velocity - the inputs behind the 13D Greediness Score.
Frequently asked questions
- Is insider trading data legal to use?
- Yes. Form 4 filings, congressional STOCK Act reports, and Schedule 13D filings are public disclosures required by law. Greedy Insider reads these primary sources from SEC EDGAR and the official congressional clerks and analyzes their structure. Nothing here is investment advice.
- Does a high Greediness Score mean I should buy?
- No. The score describes how a filing is structured - who traded, how unusual the trade was, how fast it was disclosed, and who traded alongside them. It is a research prioritization aid, not a prediction of returns, and our own historical validation has not demonstrated predictive power.
- Which insider transactions carry the most information?
- Open-market purchases made with an insider’s own cash (transaction code P), especially by senior executives and especially when several insiders buy together, are the most informative. Sales and compensation mechanics (codes S, A, M, F, G) are far noisier.
Educational analysis only. Nothing on this page is investment advice, and the Greediness Score does not predict returns.