SECURITIES AND EXCHANGE COMMISSION: (SEC) A federal government agency that regulates the trading of corporate stock to protect investors against unscrupulous practices. Like a number of other federal regulatory agencies, the SEC was established in the 1930s--1934 to be exact. The impetus for its formation was to prevent investors from manipulating the stock market and to prevent other practices that contributed to the 1929 stock market crash. The SEC has all sorts of rules governing the stock market, including information disclosure, insider trading, speculation, and use of credit. See also | regulation | corporate stock | stock market | speculation | credit |