President-elect Barack Obama named former Securities and Exchange Commissioner Mary Schapiro to head the much-criticized agency,
Also, Gary Gensler was named to head the Commodity Futures Trading Commission and Daniel Tarullo to fill an empty Federal Reserve seat.
All three will need to be confirmed by the Senate next year.
Obama is expected to install GOP Rep. Ray LaHood of Illinois as transportation secretary.
Schapiro, who currently heads a nongovernment regulatory group for securities firms, is also a former head of the Commodities Futures Trading Commission and former member of the SEC.
She has been appointed to government posts by two Republicans presidents and one Democratic chief executive.
If confirmed, she would take over an agency that has been criticized for failing to detect signs of trouble on Wall Street, where enormous losses by banks have contributed heavily to the current financial crisis.
Obama made her appointment official at a news conference on Thursday. It was not clear when the president-elect intended to formally announce his selection of LaHood, a 14-year veteran of the House who would become the second Republican to join the Cabinet-in-the-making.
The officials who described the selections did so on condition of anonymity, saying they were not authorized to discuss personnel matters not yet made public.
With a two-week vacation in Hawaii beckoning, Obama is stepping up the pace of his appointments.
Earlier in the day, he named former Iowa Gov. Tom Vilsack as agriculture secretary and Colorado Sen. Ken Salazar of Colorado to head the Interior Department.
They, like LaHood and Schapiro, will require Senate confirmation before they can take their positions in the new administration. Additionally, officials disclosed that Dr. Gail Russeau, a Chicago neurosurgeon, is a leading contender to become surgeon general.
Schapiro has spent her career in the securities field.
She is currently the head of the Financial Industry Regulatory Authority, which describes itself on its Web Site as the largest non-governmental regulator for all securities firms doing business with the U.S. public.
Two decades ago, President Ronald Reagan named her commissioner of the SEC, and she was reappointed by President George H.W. Bush and then named acting chair by President Bill Clinton.
Clinton also tapped her as head of the Commodities Futures Trading Commission, a regulatory agency.
LaHood, 63, is stepping down from his congressional seat after 14 years in Congress from the area around Peoria.
He has been at the forefront of efforts to make the floor of the House less partisan. Respected for his ability to preside, he was in the chair during most of President Bill Clinton's impeachment a decade ago.
His selection was applauded by the Laborers' International Union of North America, with General President Terry O'Sullivan saying the Republican "has been a friend to our union when it comes to construction and transportation issues."
Defense Secretary Robert Gates, whom Obama asked to remain in office, is the other Republican tapped so far for the ncoming Cabinet. He has yet to announce choices for the Labor Department, senior intelligence positions or the Office of U.S. Trade Representative.
Rep. Xavier Becerra, D-Calif., had been penciled in as trade representative, but he announced on Tuesday he intends to remain in the House.
In addition, numerous sub-Cabinet posts remain unfilled. Obama introduced Vilsack and Salazar at a now-familiar ritual, a news conference where the president-elect makes his announcement, then takes a few questions from reporters.
Asked for the second day about a political scandal roiling his home state of Illinois, he said, "It's a little bit frustrating" to not talk in detail about the investigation into charges that Illinois Gov. Rod Blagojevich schemed to name Obama's replacement in the U.S. Senate based on who offered the best political or financial deal. Blagojevich was arrested last week by the FBI.
Neither Obama nor anyone on his team has been accused of any wrongdoing in the probe. But the president-elect has directed transition aides to detail who on his side had contact, and what kind, with Blagojevich or his staff.
"There's been a lot of speculation in the press that I would love to correct immediately," Obama said in response to a question. He said his team is "abiding by the request of the U.S. attorney" to not release the results of the internal investigation, already compiled, until next week.
"It's not going to be that long," Obama said.
Vilsack is be the fourth former presidential rival to join Obama's administration. Others include Vice President-elect Joe Biden, Sen. Hillary Rodham Clinton, who has been tapped for secretary of state, and New Mexico Gov. Bill Richardson, selected to head the Commerce Department.
Salazar was elected to the Senate in 2004, the same year as Obama. His appointment means Colorado Gov. Bill Ritter will name a successor to serve until the 2010 elections. Several Democrats pointed to Rep. John Salazar, the senator's brother, as a leading possibility to take the seat.
Salazar's office issued a statement this week praising his brother's selection but making no mention of the possibility of succeeding him in the Senate.