The head of City watchdog the Financial Services Authority (FSA) is to step down in the summer.
Hector Sants has resigned after three years as chief executive, and the process to appoint his successor will be announced in due course, the regulator confirmed.
Mr Sants had been vocal in opposing plans by the Conservatives to disband the FSA and hand greater powers to the Bank of England.
With the future of the FSA unclear after the general election, it is thought the FSA will hold off until after then before deciding on plans for a successor.
The FSA stressed it was a "personal decision" by Mr Sants to quit and that it would be business as usual for the chief executive as he works out a six-month notice period.
He said he always planned to serve a three-year term as head of the FSA.
"When I was appointed I told the board that I planned to serve as CEO for three years, and I intend to stick to that timetable," he said.
Mr Sants - a former Credit Suisse banker - headed the FSA through the most testing time in its history.
He recently pledged a tougher, more intrusive regime of regulation after the FSA came in for heavy criticism over its failure to anticipate and prevent the banking crisis.
Mr Sants publicly admitted that mistakes were made by the regulator and told the industry to "be afraid" under a new hard-line approach.
