St George managing director and chief executive Paul Fegan has resigned, ending his six-year involvement with the bank.
The news comes less than a week after St George shareholders positively endorsed the merger between Westpac and St George.
"Given that St George shareholders have overwhelmingly endorsed the merger, it is now appropriate to make my decision about the future," he said.
"I am very proud that I leave the bank in a very good position, particularly given the challenges the sector has faced around the world."
"I am also very pleased that St George... is going to merge to create one of the largest and strongest financial institutions in Australia," Fegan said.
Fegan's official last day is December 8, 2008, however, he will be taking annual leave commencing November 28.
Fegan will receive approximately $2 million as a termination payment.
"On behalf of the St George Board, I would like to thank Paul sincerely for his leadership of the bank through a most difficult external environment, and for his assistance to the board during the Westpac merger process," St George chairman John Curtis said.
Recently-appointed Westpac chief executive and managing director Gail Kelly also thanked Fegan for his contribution to the bank.
"I have thoroughly enjoyed working with Paul over the past six years," she said.
"I would particularly like to thank him for his strong leadership of St George over this challenging 2008 year and for his assistance in ensuring the merger gets off to a good start."