Securities and Exchange Commission Chair Mary L. Schapiro will step down on Dec. 14, the commission announced Monday.

Schapiro became chair of the SEC in the wake of the financial crisis in January 2009. The commission said in a statement released Monday that she “strengthened, reformed, and revitalized the agency” during her tenure as she managed a “rigorous enforcement and examination program, and shaped new rules by which Wall Street must play.”

“It has been an incredibly rewarding experience to work with so many dedicated SEC staff who strive every day to protect investors and ensure our markets operate with integrity,” Schapiro said in a statement.  “Over the past four years we have brought a record number of enforcement actions, engaged in one of the busiest rulemaking periods, and gained greater authority from Congress to better fulfill our mission.”

Schapiro, who served as head of the SEC for four nearly years, had one of the longest tenures as chair, having served longer than 24 of the previous 28 chairmen.   She was appointed by President Obama on Jan. 20, 2009, and unanimously confirmed by the Senate. 

During her tenure, Schapiro worked to bolster the SEC’s enforcement and examination programs. In each of the past two years, the SEC has brought more enforcement actions than ever before, including 735 enforcement actions in fiscal year 2011 and 734 this year.

Schapiro previously was a commissioner at the SEC from 1988 to 1994.  She was appointed by President Reagan, reappointed by President George H.W. Bush in 1989, and named Acting Chairman by President Clinton in 1993.  She left the SEC when President Clinton appointed her as chairman of the Commodity Futures Trading Commission, where she served until 1996.  She is the only person to have ever served as chairman of both the SEC and CFTC.

As SEC chairman, Schapiro also serves on the Financial Stability Oversight Council, the FHFA Oversight Board, the Financial Stability Oversight Board, and the IFRS Foundation Monitoring Board.