Form 4

Form 4 is the workhorse disclosure of US insider trading law. It is mandated by Section 16(a) of the Securities Exchange Act of 1934 and applies to officers, directors, and any beneficial owner of more than 10% of a registered equity class. Each filing itemises the transaction date, the type of transaction (open-market purchase, sale, option exercise, grant), the number of shares, the price, and the resulting total holding.

The two-business-day deadline (tightened from the old end-of-month rule by Sarbanes-Oxley in 2002) is what makes the signal timely. An open-market purchase coded P carries far more information than an automatic grant coded A or a sale under a pre-set plan, because it reflects a discretionary, cash-out-of-pocket decision.