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

In addition, the SEC said it engaged in one of the busiest rulemaking periods in decades. Due to new rules now in place, investors can get clear information about the advisers they invest with, vote on the executive compensation packages at companies they invest in, benefit from additional safeguards that protect their assets held by investment advisers, and get access to more meaningful information about company boards and municipal securities, according to the SEC.

“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,” Schapiro said. “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 said it has also 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 agency said it worked to improve the structure of the market by approving a series of measures that have helped to strengthen equity market structure and reduce the chance of another Flash Crash. Among other things, the commission said 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.

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, according to the SEC.

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, the SEC said.

There is no word yet on who will likely be appointed to replace Schapiro.