FINANCIAL MARKETS : Computer Security at Stock Exchanges Called Vulnerable

WASHINGTON — Internal security weaknesses of stock exchange computer systems raise risks of sabotage that “could literally bring securities trading to a halt,” even though the systems are well protected against attack by outsiders, a congressional study disclosed Tuesday.

The study by the General Accounting Office found a number of internal control weaknesses at the computer centers of the nation’s two major stock exchanges and the National Assn. of Securities Dealers, which oversees the over-the-counter market.

A related GAO study called for beefed-up security measures for the electronic funds transfer systems used by the Federal Reserve System and most of the nation’s banks.