WASHINGTON  The chairman of the Securities and Exchange Commission, a longtime proponent of deregulation, acknowledged on Friday that failures in a voluntary supervision program for Wall Street’s largest investment banks had contributed to the global financial crisis, and he abruptly shut the program down.

The S.E.C.’s oversight responsibilities will largely shift to the Federal Reserve, though the commission will continue to oversee the brokerage units of investment banks.

Also Friday, the S.E.C.’s inspector general released a report strongly criticizing the agency’s performance in monitoring Bear Stearns before it collapsed in March. Christopher Cox, the commission chairman, said he agreed that the oversight program was “fundamentally flawed from the beginning.”

“The last six months have made it abundantly clear that voluntary regulation does not work,” he said in a statement. The program “was fundamentally flawed from the beginning, because investment banks could opt in or out of supervision voluntarily. The fact that investment bank holding companies could withdraw from this voluntary supervision at their discretion diminished the perceived mandate” of the program, and “weakened its effectiveness,” he added.