How to read an SEC Form 4

Who has to file one

Section 16 of the Securities Exchange Act of 1934 covers a company’s directors, its officers, and any beneficial owner of more than 10% of a registered class of its equity securities. Those people are the "insiders" for reporting purposes.

Insiders file three related forms. Form 3 is the initial statement of ownership, filed when someone first becomes an insider. Form 4 reports changes in that ownership. Form 5 is an annual catch-up for certain transactions that were exempt from immediate reporting.

When it is due

A Form 4 is generally due before the end of the second business day following the transaction. That short window is what makes the form useful: the filing usually appears within days of the trade, not at the end of a quarter.

Form 3 is generally due within 10 days of becoming an insider, and Form 5 within 45 days after the issuer’s fiscal year end.

Table I and Table II

Table I covers non-derivative securities — ordinary common stock. Table II covers derivative securities such as stock options, restricted stock units, warrants, and convertible instruments.

Each row carries a transaction date, a transaction code, the number of shares, the price, whether the transaction was an acquisition (A) or disposition (D), and the amount of stock the insider beneficially owned afterward. That last column is the one most readers skip and the one that gives the transaction its context.

The transaction codes that appear most often

The single-letter code in each row tells you what kind of event it was. A few appear constantly:

• P — an open-market or private purchase.
• S — an open-market or private sale.
• A — a grant, award, or other acquisition from the company, such as vesting restricted stock.
• M — the exercise or conversion of a derivative security into stock.
• F — shares surrendered back to the issuer to cover tax withholding.
• G — a bona fide gift.
• C — the conversion of a derivative security.

Why the distinction matters

A row coded A or M or F is largely compensation mechanics. Equity vested, an option was exercised, or shares were withheld to pay the resulting tax bill. Those rows move the ownership total but do not reflect a discretionary decision to buy at the current price.

A row coded P is a different thing: the insider chose to put money in at a known price on a known date. Many readers filter Form 4 activity down to P and S rows for exactly this reason.

The Rule 10b5-1 checkbox

Form 4 includes a checkbox indicating that a transaction was made under a Rule 10b5-1 trading plan — a written plan adopted in advance, at a time when the insider did not have material non-public information.

A sale executed under such a plan was scheduled earlier, which is a meaningfully different fact from a discretionary sale made this week. The checkbox and the plan adoption date are stated on the filing itself, so this is something you can verify rather than infer.

Always finish at the source

Every Form 4 on EDGAR carries the filer’s name, the issuer, the accession number, and the primary document. Any summary — including ours — is a starting point. The filing is the record.