Form 4
The SEC filing that discloses insiders' trades in their company's shares, due within two business days of the transaction.
A Form 4 is filed with the SEC by a company's directors and officers, and by holders of more than 10 percent of its shares, when they buy, sell or receive equity. It must be filed within two business days of the transaction. Each line shows the transaction code, shares, price and holdings after the trade.
On our site, Form 4s are listed with their transaction type. Open-market purchases and sales are the most informative; equity grants and tax-withholding entries are routine.
Traders care because insider purchases with personal money are a signal some weigh heavily, while sales are often for diversification or taxes and tell less.
Worked example (illustrative numbers, not real data): a director buys 20,000 shares at 50 dollars, about 1 million dollars, in the open market. That is a purchase with personal cash. A sale of 20,000 shares under a pre-set plan carries less information than the same sale made without one.