Securities markets investigation : hearings before a subcommittee of the Committee on Interstate and Foreign Commerce, House of Representatives, Eighty-seventh Congress, first session on H.J. Res. 438, joint resolution to amend the Securities Exchange Act of 1934 so as to authorize and direct the Securities and Exchange Commission to conduct a study and investigation of the adequacy, for the protection of investors, of the rules of national securities exchanges and national securities associations, June 27, 28, 29, and July 10, 1961.