The SEC requires disclosure of things that that relate to a company's financial condition, operating results, management compensation and other important areas. Disclosure requirements initially came about with the passing of the Securities Act of 1933 and the Securities Exchange Act of 1934. Since then, additional acts like the Sarbanes-Oxley Act have furthered the requirements of disclosures by a public company.
Brokerage firms and analysts must also disclose information that relates to investment decisions. To limit conflict of interest issues, analysts must disclose any equities that they own. And company officers of investment banks must make personal disclosures regarding the securities they own as well as securities owned by family members.