8k Definition

The form used by companies to comply with Securities and Exchange Commission requirements to report material developments. Although much case law has been developed to determine exactly what is a material development, the term means, in general, something that a reasonable shareholder would likely consider important to making an investment decision. Some material events include a planned merger, an out-of-the-ordinary purchase, the sale of significant assets, the resignation of the chief executive officer, the firing of the company’s auditor, or a bankruptcy filing.
Webster's New World Finance