Walter was appointed by President George W. Bush to the SEC and was sworn in on July 9, 2008. Under designation by Obama, she served as acting chairman during January 2009, according to the SEC.

Prior to her appointment as an SEC commissioner, Walter served as senior executive vice president of regulatory policy and programs for FINRA. She held the same position at NASD before its 2007 consolidation with NYSE Member Regulation.

Walter also coordinated policy issues across FINRA and oversaw a number of departments including investment company regulation, member education and training, investor education and emerging regulatory issues. She also served on the board of directors of the FINRA Investor Education Foundation.

Prior to joining NASD, Walter served as the general counsel of the Commodity Futures Trading Commission. Before joining the CFTC in 1994, she was the deputy director of the SEC's Division of Corporation Finance. She served on the SEC's staff beginning in 1977, both in that division and in the Office of the General Counsel.

Before joining the SEC, Walter was an attorney with a private law firm.

Obama praised Schapiro's tenure at the agency.

 "When Mary agreed to serve nearly four years ago, she was fully aware of the difficulties facing the SEC and our economy as a whole," Obama said. "But she accepted the challenge, and today, the SEC is stronger and our financial system is safer and better able to serve the American people – thanks in large part to Mary's hard work."