By the InsiderAlpha research team · Updated Jul 16, 2026 · Sourced from SEC EDGAR filings

What is SEC Form 4?

SEC Form 4 is the U.S. Securities and Exchange Commission filing that corporate insiders — directors, officers, and beneficial owners of more than 10% of a company's stock — must submit to report changes in their ownership of the company's securities. It is required under Section 16(a) of the Securities Exchange Act of 1934, and since the 2002 Sarbanes-Oxley Act it must be filed electronically on EDGAR within two business days of the transaction.

Because the deadline is so short, Form 4 is the fastest, most reliable public window into what the people who run a company are doing with their own money. InsiderAlpha ingests every Form 4 from SEC EDGAR in real time so you see these trades the moment they are filed.

Who has to file Form 4?

Directors and named executive officers (CEO, CFO, COO, and other "Section 16 officers") of public companies.
Beneficial owners of more than 10% of any class of a company's registered equity — often hedge funds, private-equity firms, and activist investors.
Certain related parties — trusts, family members, and affiliated entities whose holdings are attributed to an insider.

How to read a Form 4

A Form 4 has two tables. Table I covers non-derivative securities (ordinary common stock). Table II covers derivative securities (options, warrants, convertible notes, RSUs). For each transaction the form reports:

Transaction date — when the trade actually happened (not when it was filed).
Transaction code — a one-letter code describing the nature of the trade (see below).
Amount, price, and resulting shares owned — how many shares changed hands, at what price, and the insider's total stake afterward.
Ownership type — "D" for direct ownership or "I" for indirect (e.g. held through a trust or LLC).

Common transaction codes

P — Open-market or private purchase
S — Open-market or private sale
A — Grant or award (usually equity compensation)
M — Exercise or conversion of a derivative security
F — Shares withheld to pay taxes or an exercise price
G — Bona-fide gift

Open-market purchases (code P) are widely considered the most informative signal because the insider is committing personal capital with direct knowledge of the business. Awards (A) and tax-withholding dispositions (F) are routine compensation events and carry far less information.

Direct vs. indirect, derivative vs. non-derivative

Two distinctions trip up first-time readers. Indirect holdings (code "I") are real economic exposure held through an intermediary — they count. And a Table II derivative exercise (code M) often pairs with a same-day sale (code S) of the underlying stock; that is a mechanical compensation transaction, not a conviction bet.

Why does it matter?

Academic research — notably Lakonishok & Lee (2001) and Cohen, Malloy & Pomorski (2012) — finds that routine insider selling contains little predictive information, but opportunistic insider buying, and especially clustered buying by several insiders at once, is associated with positive abnormal returns over the following months.

How InsiderAlpha helps

InsiderAlpha deduplicates Form 4 amendments, classifies every transaction, flags Rule 10b5-1 plan trades, and scores the high-conviction signals — large open-market officer buys and cluster buying — into a daily plan.

Browse the latest Form 4 filings → · How to read insider buying signals →