A bill to amend the Securities and Exchange Act of 1934 to authorize the Securities and Exchange Commission to prohibit brokers or dealers from trading listed securities otherwise than on national securities exchanges in the event the Commission determines that such trading is contrary to the public interest and the protection of investors.

Authorizes the Securities and Exchange Commission to prohibit brokers or dealders from trading listed securities otherwise than on national securities exchanges in the event the Commission determines that such trading is contrary to the public interest and the protection of investors. States that any rule promulgated pursuant to this Act shall not become effective until the rules of national securities exchanges fixing rates of commissions have been eliminated and shall not remain in effect after the Commission has determined that a national market system for securities has been established or April 30, 1978, whichever is earlier.