Form 3 vs Form 4 vs Form 5: what's the difference?

Section 16 insiders file three related forms. They're often confused, but only one of them reports fresh, voluntary trades.

Form 3 — the starting line

Filed within 10 days of becoming an insider (new officer, new director, crossing 10% ownership). It's a snapshot of what they own on day one — no transactions at all. A Form 3 showing a large existing stake is context, not action.

Form 4 — the one that matters

Filed within two business days of any change in ownership: buys, sells, grants, exercises, gifts. This is the only form fast enough and specific enough to trade on, and the open-market purchases inside it (code P — see transaction codes) are the raw material for cluster-buy detection.

Form 5 — the annual catch-up

Filed within 45 days of fiscal year-end for transactions that were exempt from Form 4 (small gifts, certain plan transactions) or — embarrassingly — trades that should have been on a Form 4 and weren't. By the time something appears on a Form 5 it can be a year old. Historical interest only.

Bottom line

Watch Form 4s, ignore the rest for signal. We parse every Form 4 as it hits EDGAR and surface the ones that matter on the stocks directory and in real-time alerts.