Form 4 is a filing required by the U.S. Securities and Exchange Commission (SEC) for all corporate insiders. This filing must be completed whenever there is a material change in the holdings of a company's insiders, such as directors, officers or beneficial owners who hold 10% or more of the company's shares. These filings are of utmost importance because they are used to ensure that the company's corporate insiders are not taking advantage of their inside knowledge to unfairly benefit their own investments.

Form 4 is an SEC form that must be completed and submitted to the SEC no later than two business days after the date of the material transaction. This filing must include information such as the trading date, the number of shares traded, the cost of the transaction, and any statutory or non-statutory profit-sharing or hedging arrangements. The form must also include the insider's identity, the type of security and the nature of the transaction.

Failure to file a timely Form 4 could result in civil or possibly even criminal sanctions. The SEC may also impose fines on violators. In some cases, the SEC may even pursue injunctive relief – meaning that certain insiders may be temporarily barred from further filings.

Form 4 filings are critical for investors to remain up-to-date on the trading and investments of corporate insiders. The information contained in Form 4 provides a valuable window into the investment and trading activities of company insiders, helping investors identify potential conflicts of interest. This information can then be used by investors to better gauge how company insiders may be affecting the direction of the company.