Securities and Exchange Commission Chairman William H. Donaldson announced that he would step down at the end of the month.
Donaldson, a former investment banker who was appointed by President Bush in 2003 to replace Harvey Pitt, is the commission's 27th chairman.
"I have been honored to serve as chairman," Donaldson said in a statement. "Although there will always be more work to be done to preserve and enhance the integrity and strength of our nation's corporations and markets, I believe the time has come for me to step down and return to the private sector and my family."
Commenting on his tenure, which came amid a spate of scandals that shook investors and rocked corporate America, Donaldson said, "It may well be remembered as the most consequential and productive period in the commission's history since its founding in 1934."
As soon as he took the helm of the agency in February of 2003, Donaldson was charged with the task of implementing the landmark Sarbanes-Oxley Act and with overseeing the selection of the chairman of the then-newly created Public Company Accounting Oversight Board.
Donaldson, who helped found Donaldson, Lufkin & Jenrette, also served as chairman of the New York Stock Exchange, was chief executive of Aetna and was a founder of Yale University's Graduate School of Management.
