WASHINGTON (AP) - Mary Schapiro is stepping down as chairman of the Securities and Exchange Commission after helping lead the U.S. government's regulatory response to the 2008 financial crisis.

The SEC says Schapiro will leave on Dec. 14. She was appointed by President Barack Obama in the midst of the worst financial crisis since the Great Depression. She took over after the agency failed to detect the Bernard Madoff Ponzi scheme.

Schapiro is credited with helping reshaping the agency during a tumultuous period. But critics say she failed to act aggressively to bring charges against leading figures who contributed to the financial crisis.

It isn't clear who will replace Schapiro. But several news reports suggest Mary John Miller, a top Treasury Department official, is a leading candidate.

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