Barrick Gold Corp. has abruptly replaced its chief executive and installed a former U.S. investment banker as co-chairman of its board of directors, saying they will help the company restore its lacklustre stock price.

Jamie Sokalsky, who was the Toronto-based company's chief financial officer, has replaced Aaron Regent as Barrick's chief executive and president — effective immediately.

At the board of directors, John Thornton — a former president of Goldman Sachs, the U.S. investment banking giant — will join Barrick founder Peter Munk as co-chairman.

Munk, 84, who is one of Canada's best-known businessman, issued a statement thanking Regent for his efforts but making it clear they weren't enough.

"We are fully committed to maximizing shareholder value, but have been disappointed with our share price performance," Munk said.

Barrick stock closed Tuesday at $43.70, down sharply from its 52-week high of $55.36. While the price of gold has declined from record highs, many analysts have said shares of gold companies including Barrick underperformed the metal.

Munk is often blunt in his public appraisals of Barrick's top executives and, characteristically, he told shareholders at the company's annual meeting last month that the company's shares price wasn't satisfactory.

"There are many reasons for it, but not to face up to it and not to talk about it would be the gravest mistake a board and management and people responsible for the welfare of this company could do," Munk said at the time.

Regent, who joins several other Barrick CEOs who have been abruptly replaced over the years, had been Barrick's top executive since January 2009. He had been previously co-chief executive of the Brookfield Infrastructure Group.

Munk said the board of directors has confidence in Sokalsky's experience and commitment.

Sokalsky joined Barrick in 1993 and has been the company's chief financial officer since 1999. Prior to joining the mining company, he had been an executive at Canadian food processing company George Weston Ltd. for 10 years.

Regarding Thornton's elevation to the role of co-chairman, Munk said "John's knowledge and experience of global business affairs are truly exceptional and we are all fortunate that he has agreed to take on this important role."

Besides his role at Barrick, Thornton is also chairman of The Brookings Institution — a U.S. think-tank — and holds degrees from Harvard College, Oxford University and the Yale School of Management.