Securities Exchange Act of 1934
The law governing the SECONDARY market: it created the SEC, requires broker-dealers and exchanges to register, empowers the Fed to set margin (Reg T), and contains the antifraud and antimanipulation provisions.
Later statutes complete the family: the Trust Indenture Act of 1939 (corporate bond indentures), the Investment Company Act of 1940 (funds), the Investment Advisers Act of 1940 (advisers), and the Securities Investor Protection Act of 1970 (SIPC).