SEC (Securities and Exchange Commission)

The primary U.S. federal agency responsible for regulating securities markets, protecting investors, and enforcing securities laws. Founded in 1934 in the aftermath of the 1929 crash, with Joseph P. Kennedy as its first chairman, the SEC oversees stock exchanges, broker-dealers, mutual funds, and financial advisers. The agency's enforcement actions -- from insider trading prosecutions to fraud cases -- shape market behavior, and its rulemaking on issues like market structure and disclosure requirements affects every participant in the financial system.