Form 4 (Insider Trading Report)
A filing made within two days when a company's officers, directors, or 10% shareholders buy or sell their own company's stock — each transaction carries a code showing «what kind it is».
Who = officers, directors, and shareholders holding 10% or more
The filing also states the number of shares held after the transaction.
In plain terms
It's like a shop owner posting a notice on the board out front whenever they buy or sell goods from their own shop. The people who see the company's situation most closely disclose the very fact that they traded their own company's stock.
When a company's officers or directors buy or sell their own company's stock, they report it to the SEC within two business days. That document is Form 4. Unlike 13F, which is compiled and filed each quarter, it comes out right after the trade, so it's much faster.
Each filing carries a one-letter code for «what kind of transaction» it was. P means shares bought with the filer's own money, S means sold, and F means shares withheld by the company to cover taxes.
Unlike 13F, which is gathered once a quarter, this arrives right after the trade — so the date is exact to the day.
What it tells you
Lumping everything together as «an officer sold» changes the meaning. Counting the roughly 78,000 filings submitted in Q2 2026 by code gives sales (S) 35.2% · grants (A) 24.5% · option exercises (M) 13.8% · tax withholding (F) 11.9% · purchases (P) 6.8%.
Among these, the two that reflect the person's own trading decision are P and S. F is the company automatically withholding the tax portion when shares received as incentive compensation vest, and A (grant) and M (option exercise) are not buy-or-sell decisions either.
Formula
Who = officers, directors, and shareholders holding 10% or more Deadline = within 2 business days of the transaction date Each transaction carries a code — P buy · S sell · A grant · M option exercise · F tax withholding
What high or low means
The filing also states the number of shares held after the transaction. Even the same «sold 100,000 shares» differs there depending on whether it was 100,000 out of 1 million shares or 100,000 out of 120,000 shares.
It also shows whether the trade was made under a pre-arranged trading plan (10b5-1). If shares were sold automatically on a schedule set up in advance, it is hard to say the seller was reacting to anything at the moment of the sale.
Counting only the number of filings without looking at the codes moves you away from the facts. As the distribution above shows, a large share of what gets read as "an insider put stock on the market" is taxes, awards, or option exercises.
Purchases (P) are rare to begin with (6.8% of the total). Executives usually receive stock as compensation rather than paying money for it. So a P stands out, but the filing does not say what it means.
The 10b5-1 checkbox was added after the filing form changed in 2023. Trades before that have no such box, so there is no way to tell whether they followed a plan.
When there are several insiders, multiple filings can pile up on the same day. Unless you separate them by person, one person's trade can look like a company-wide move.
Metrics to read alongside
See it in real stocks
Search US stocks on Stocklore to see Form alongside the sector benchmark.
This explanation is for information and reference only and is not a recommendation to buy or sell any security. Investment decisions and their consequences are your own.