Susanne Craig and Ben Protess / New York Times News Service

Mary Schapiro, who overhauled the Securities and Exchange Commission after the financial crisis, announced Monday that she is stepping down as chairwoman of the agency.

In recent days, the SEC informed the White House and Treasury Department that Schapiro planned to leave Dec. 14, becoming the first major departure from the Obama administration's team of financial regulators. Schapiro will also relinquish her position as one of the five members of the agency's commission, the group that oversees Wall Street and the broader financial markets.

The White House announced Monday that President Barack Obama was naming Elisse Walter, a commissioner at the SEC, as the new chairwoman. In a somewhat surprising step, Walter will not be an interim chairwoman, but could have the top job for the foreseeable future.

Her appointment will not require congressional approval because the Senate previously confirmed her as a commissioner.

Eventually, according to a person briefed on the matter, the White House is expected to nominate another agency chief.

“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.”

The move, which follows a bruising, four-year tenure, was widely telegraphed. Schapiro, 57, has confided in staff members for more than a year that she was exhausted and hoped to leave after the November elections.