Insider filings: Forms 3, 4 and 5, and the codes that matter

Officers and directors report their trades within two business days. Reading the codes keeps you honest.

Company insiders — officers, directors, and over-10% owners — must report their transactions in company stock: Form 3 on becoming an insider, Form 4 within two business days of most transactions, Form 5 for an annual catch-up. Unlike 13Fs, this data is nearly real-time. The catch is that most Form 4 lines are not what a casual reader calls "buying" or "selling."

The transaction codes

Every line carries a code. The ones you will see most: P — open-market purchase; S — open-market sale; A — grant or award; M — option exercise; F — shares withheld to cover taxes; G — gift. An insider who exercises options (M) and immediately sells (S) has mostly executed compensation, not expressed a view. Shares withheld for taxes (F) are reported as dispositions but are involuntary.

Why open-market purchases are the studied signal

A code-P purchase is an insider spending their own cash at market prices — the one transaction type with no compensation explanation. That is why this site's insider statistics count only code-P open-market purchases as "insider buying," and why option exercises and awards are never counted as buys. Sales are murkier: insiders sell to diversify, pay taxes, and fund lives, so a sale is weak evidence of anything; scheduled 10b5-1 plan sales, where disclosed, are weaker still.

Cluster buying

One insider buying is an anecdote; several insiders of the same company making open-market purchases within a few weeks is a pattern worth listing. The insider activity page keeps a cluster view — multiple distinct insiders, code-P only, within 30 days — alongside the raw feed, with each line linking to the original filing.