A document that must be filed with the Securities and Exchange Commission (SEC) whenever there is a material change in the holdings of company insiders. Insiders required to submit a Form 4 include directors and officers of the company as well as any shareholders owning 10% or more of the company's outstanding stock. Taobiz explains Form 4 This two-page document covers any buy-and-sell orders on the open market as well as the exercise of company stock options. A Form 4 is mandatory within two business days starting from the end of the day the material transaction occurred. This filing is related to Form 3 and the Form 5, which also cover changes to the company insider holdings.