The U.S. Securities and Exchange Commission (SEC) is an independent federal regulatory agency responsible for regulating securities markets in the United States, enforcing federal securities laws, and protecting investors from fraud and manipulation. Established in the wake of the 1929 stock market crash and the Great Depression through the Securities Exchange Act of 1934, the SEC oversees the offering and trading of securities (including stocks, bonds, and mutual funds), ensures fair and orderly markets, and regulates broker-dealers, investment advisers, mutual fund companies, and public companies through disclosure requirements. The agency investigates violations, brings civil enforcement actions, combats insider trading, promotes disclosure of important market information, maintains the integrity of the securities markets, and collaborates with other regulators like the Department of Justice for criminal matters. Its structure includes a five-member bipartisan commission appointed by the President and confirmed by the Senate, operating through divisions such as Enforcement, Corporation Finance, Trading and Markets, Investment Management, and Economic and Risk Analysis, supported by regional offices. The SEC has been involved in major historical events including enforcement of the Sarbanes-Oxley Act post-Enron scandal and adapting to modern challenges like cryptocurrency regulation. The agency has faced controversies including allegations of failing to prevent the 2008 financial crisis, criticism for ignoring evidence of Bernie Madoff's Ponzi scheme, data breaches, lenient settlements with banks post-2008, and ongoing debates about climate disclosures and crypto asset regulation. It has also been criticized for being underfunded relative to market size and for the 'revolving door' with industry.