Since her appointment to the SEC in 1997, Unger has advocated policies to promote market integrity, efficiency and investor protection, with a particular emphasis on the impact of technology on the securities industry.

"It has been a great honor to serve on the commission during the most dramatic period of technological innovation and transformation in the history of America's capital markets," Unger said.

With the departure of SEC chair Arthur Levitt in February, Unger was appointed acting chair by President Bush, during which she led the commission's efforts to improve the objectivity and independence of securities analysts. Her role as acting chair ended when Harvey Pitt was appointed the position in August. Unger's term as commissioner was not set to end until December 2002.

Unger has not yet accepted a position in the private sector.