Insider activity
What is a Form 4?
Updated
A Form 4 is the document a corporate insider must file with the SEC within two business days of buying, selling, or otherwise changing their ownership of company stock. “Insider” has a precise meaning here: officers, directors, and beneficial owners of more than 10% of a class of equity, the people covered by Section 16 of the Securities Exchange Act. Because the deadline is so short, Form 4s are among the timeliest signals in all of SEC disclosure.
The Section 16 trio
Form 4 sits in a family of three. Form 3 is the initial statement, filed within 10 days of becoming an insider, showing what they own on day one. Form 4 reports changes as they happen. Form 5 is an annual catch-up, due within 45 days of fiscal year end, for exempt transactions that were not reported earlier, such as small acquisitions. Gifts used to sit on Form 5 too, but since 2023 they must be reported on Form 4 within two business days. In practice, Form 4 is where nearly all the information is.
How to read one
Each transaction line carries a code, and the code is everything. “P” is an open-market purchase, the strongest signal, since insiders spend their own cash for only one reason. “S” is an open-market sale, which is more ambiguous: diversification, taxes, and divorce all prompt sales. “A” is a grant or award, “M” is an option exercise, “F” is shares withheld to cover taxes, and “G” is a gift. A large “M” followed by an equally large “S” is routine compensation mechanics, not conviction.
Since 2023, Form 4 also carries a checkbox indicating whether a trade was made under a pre-arranged Rule 10b5-1 plan. A planned sale scheduled months in advance says far less than a discretionary one. Table I covers non-derivative securities, chiefly common stock; Table II covers derivatives like options and RSUs.
Ownership form matters too. Each line is marked direct (“D”) or indirect (“I”). Indirect holdings sit in trusts, family partnerships, or a spouse’s name, with a footnote explaining the arrangement. Section 16 reaches any shares in which the insider has a pecuniary interest, so a sale “by the Smith Family Trust” is still the insider’s sale. The footnotes on a Form 4 are short and frequently where the real story is: weighted-average sale prices, price ranges, and plan adoption dates all live there.
Using Form 4 data
Single filings are noisy; patterns are not. Clusters of open-market buys by multiple insiders, especially after a price decline, have historically been one of the more informative public signals. Scrutar aggregates every Form 4 as it is filed: see NVIDIA’s insider trading history for a single company, JPMorgan’s insider activity for a bank’s typically heavy grant traffic, or the market-wide insider trading feed for the latest filings across all covered companies.
The two-business-day rule, tightened from a far looser standard by Sarbanes-Oxley in 2002, means the market learns about insider conviction, or the lack of it, while the information is still fresh.