SEC Chief to Resign; Reign Covered Crash, Scandals

David S. Ruder announced his resignation Thursday as chairman of the Securities and Exchange Commission after guiding the agency through two tumultuous years that included the 1987 stock market crash and a historic investigation of corruption on Wall Street.

Ruder, in a letter to President Bush, said he planned to return to the faculty of Northwestern University School of Law at the end of August. He left there in 1987 to head the SEC, which regulates the nation’s financial markets and oversees disclosure requirements for U.S. publicly traded firms.

The date of his resignation depends on when his successor is appointed. He gave no reason for leaving, but Bush had been widely expected to name someone else to the post even though senior Democrats in Congress were urging that Ruder stay on. His term expires in June, 1991.

On the list of possible successors are attorney Thomas A. Russo, a former division director at the Commodity Futures Trading Commission; Edward H. Fleischman, who already holds a seat on the five-member SEC, and Kraft Inc. Chairman John M. Richman of Chicago.

White House spokesman B. J. Cooper said the Administration was reviewing the appointment and declined further comment.

When Ruder, 60, took over the SEC, he had a reputation as a respected legal expert and, as former dean of the Northwestern Law School, as a skilled administrator.