After nearly four years in office, SEC Chairman Mary L. Schapiro said that she will step down on December 14, 2012.

“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,” said Schapiro. “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.”

The SEC said that in each of the past two years, the agency has brought more enforcement actions than ever before, including 735 enforcement actions in fiscal year 2011 and 734 actions in FY 2012.

“I’ve been so amazed by how hard the men and women of the agency work each and every day and by the sacrifices they make to get the job done,” added Chairman Schapiro. “So often they stay late or come in on weekends to polish a legal brief, review a corporate filing, write new rules, or reconstruct trading events. And despite the complexity and the intense scrutiny, they always excel at what they do.”

As a result of the Dodd-Frank Wall Street Reform and Consumer Protection Act, the agency has implemented a new whistleblower program, strengthened regulation of asset-backed securities, laid the foundation for an entirely new regulatory regime for the previously-unregulated derivatives market, and required advisers to hedge funds and other private funds to register and be subject to SEC rules.

During Schapiro’s tenure, the SEC for the first time has required the exchanges to create a consolidated audit trail that will enable the agency to reconstruct trading across various trading venues.

Chairman Schapiro previously served as a commissioner at the SEC from 1988 to 1994.

She was appointed by President Ronald Reagan, reappointed by President George H.W. Bush in 1989, and named Acting Chairman by President Bill 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.