President Bush nominated William Donaldson, a senior Wall Street investment banker, to be the new chairman of the U.S. Securities and Exchange Commission.

Mr. Donaldson heads his own firm, Donaldson Enterprises, based in New York. He previously co-founded the investment banking firm Donaldson Lufkin & Jenrette and served as its chairman and chief executive.

Earlier in his career, Mr. Donaldson was a founder of Yale University's Graduate School of Management and served as its first dean. He also served during 1975 as counsel to U.S. Vice President Nelson Rockefeller. Before that, he was U.S. undersecretary of state under Secretary Henry Kissinger from 1973 until 1975.

"I am firmly committed to doing everything that I can do to restore the confidence of investors in the U.S. corporate and financial industry," Mr. Donaldson said following the announcement. "As my mother used to say many years ago, 'It's time for all of us to pull up our socks.'"

The nomination must still be confirmed by the Senate, where Mr. Donaldson's former association with Aetna is expected to be carefully examined. Both Aetna and Mr. Donaldson, who served as the company's chairman for about a year until April 2001, were named as defendants a year ago in several lawsuits for allegedly misrepresenting that a 2001 restructuring of the company would provide cost savings.

If confirmed by the Senate, Mr. Donaldson will replace outgoing SEC Chairman Harvey Pitt, who resigned on Election Day but has been continuing in the position until his successor can be named.