P individually and on behalf of an asserted class of small investors, filed this suit against the New York Stock Exchange, Inc., the American Stock Exchange, Inc. (Amex), and two member firms of the Exchanges (Ds). P claimed that the system of fixed commission rates, utilized by the Exchanges at that time for transactions less than $500,000, violated §§ 1 and 2 of the Sherman Act, 26 Stat. 209, as amended, 15 U.S.C. §§ 1 and 2. Ds moved for summary judgment on the ground that the challenged actions were subject to the overriding supervision of the Securities and Exchange Commission (SEC) under § 19(b) of the Securities Exchange Act of 1934, 48 Stat. 898, as amended, 15 U.S.C. § 78s (b), and, therefore, were not subject to the strictures of the antitrust laws. The District Court granted Ds motion as to all claims. The Second Circuit affirmed. It held that because the SEC, by §19(b)(9), was given specific review power over the fixing of commission rates, because of the language, legislative history, and policy of the Exchange Act, and because of the SEC's actual exercise of its supervisory power, antitrust immunity was proper.