Insider trading, explained: how to read Form 4, Congress & 13D filings

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.
• How the Signals patterns are detectedSignals are four recurring filing patterns that Greedy Insider detects with fixed, written rules: cluster buys, long congressional disclosure lag, new or amended Schedule 13D filings, and a first open-market buy after a long silence.

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.
• First Merchants CEO buys ~$916k: reading a 95 Greediness Form 4First Merchants CEO Mark K. Hardwick reported buying about 21,000 shares near $43.63 (~$916k) on August 3, 2026. The filing scored 95 on the Greediness Score. Here is the structural reading - and the limits.
• Shenandoah Telecommunications: six directors buy the same dayOn August 3, 2026, six different Shenandoah Telecommunications (SHEN) directors filed buys at $11.99. Scores ranged from 68 to 76. Here is how to read a broad director cluster without overstating conviction.
• Legato Merger Corp IV: CEO, CFO, and COO filings with $0 pricesLegato Merger Corp. IV (LEGO) showed a same-day CEO/CFO/COO "buy" cluster with reported prices of $0.00 and Strong-band scores up to 84. This case study shows why zero-price SPAC Form 4s need a different reading than open-market cash buys.
• Jefferies CEO buys ~$4.0m: a same-day CEO and CFO Form 4Jefferies Financial Group CEO Richard B. Handler reported buying about 75,531 shares at $53.09 (~$4.01 million) on August 28, 2026. The same day, CFO Matthew S. Larson bought 746 shares at the same price. Here is the structural reading.
• Biomerica: CEO and vice chairman buy the same $1.60 printBiomerica (BMRA) CEO Zackary S. Irani reported buying 31,250 shares at $1.60 ($50,000) on August 26, 2026. Executive Vice Chairman Allen Barbieri reported 20,000 shares at the same price. Both scored 82. Here is how to read a small-cap dual buy.
• Chicago Atlantic REFI: executive chairman buys ~$429kChicago Atlantic Real Estate Finance (REFI) Executive Chairman John Mazarakis reported buying about 40,181 shares at $10.67 (~$429,000) on August 26, 2026, scored 86. Here is the structural reading, including what a Form 4 does not say about a pending merger.
• What is a Form 4? How to read SEC insider transaction filingsA Form 4 is the SEC filing a company insider must submit within two business days of trading their company stock. Here is how to read who filed, which transaction codes carry information, and what a Form 4 does not tell you.
• What does a cluster buy mean, and when does it matter?A cluster buy is when three or more different insiders of the same company buy its stock within a short window. Here is what that structure can mean, when it is mechanical noise, and how Greedy Insider scores it.
• Congressional trades explained: what the STOCK Act actually tells youUnder the STOCK Act, members of Congress must report securities transactions - often days or weeks after the trade. Here is what those disclosures establish, why lag matters, and how Greedy Insider scores them.
• Schedule 13D vs 13G: activist vs passive ownership, explainedSchedule 13D and Schedule 13G both disclose large beneficial ownership, but 13D is the activist-oriented form. Here is how they differ, what to read first on a fresh 13D, and how Greedy Insider scores activist filings.
• What is a 10b5-1 trading plan? How prearranged insider trades workA 10b5-1 plan lets an insider schedule trades in advance and claim an affirmative defense against insider trading claims. Here is how the plans work, what the Form 4 checkbox tells you, and why a planned sale reads differently from a cash open-market buy.
• Form 3 and Form 5, explained: the Section 16 filings around a Form 4Form 3 is the starting holdings report when someone becomes an insider. Form 5 is the annual catch-up for certain small or exempt transactions. Here is how they fit next to Form 4, what they establish, and what they do not.
• Why insider buys carry more information than insider salesInsiders sell for taxes, diversification, 10b5-1 calendars, and liquidity. They usually buy with cash for one reason. Here is why the Form 4 tape is asymmetric, and how Greedy Insider uses that without pretending sales are worthless.
• Direct vs indirect ownership on Form 4: whose money is actually in the trade?A Form 4 can report shares held directly by the insider or indirectly through a trust, spouse, or entity. Here is how to read that field, why direct cash buys usually carry more information, and what indirect ownership does not hide.

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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.