"I very much appreciate the Senate's confirmation of these nominees. Investors and markets are best served when the SEC benefits from the dedication and broad range of views that a full five-member Commission provides. …I welcome Dan's return to the agency as we continue our efforts to protect investors and improve our markets and the economy," said SEC Chairman Mary Schapiro in a written statement.

Gallagher is currently a partner in WilmerHale's securities department and a member of its broker-dealer compliance and regulation, securities litigation and enforcement, and derivatives and futures practice groups.

The appointment marks a homecoming of sorts for Gallagher. Prior to joining WilmerHale, he was a deputy director of the Division of Trading and Markets at the SEC. During his tenure there, Gallagher played a critical role in the agency's response to the financial crisis. He worked closely with the Treasury Department, the Federal Reserve Board, the Federal Reserve Bank of New York, the Commodity Futures Trading Commission and various international regulators on matters relating to the crisis.

"Dan's achievements mirror the success of many of our securities alumni," said Professor David Lipton, director of the Securities Law Program. "The law school has consistently turned out graduates who are well trained, highly motivated, and exceptional practitioners.Dan's achievement is a tribute not only to him, but, to all of our securities alumni." Gallagher, a Republican, joins Democrat Luis Aguilar as the SEC's newest commissioners.

The agency's five commissioners are appointed by the President. Their terms last five years and are staggered so that one Commissioner's term ends on June 5 of each year. No more than three commissioners may belong to the same political party.

Gallagher was also the keynote speaker at the annual Securities Practice Group Alumni Luncheon, held at the Army and Navy Club in Washington, D.C., on Nov. 3.