(Bloomberg) -- Credit Suisse Group AG’s largest shareholder urged the troubled lender to fix its investment bank or seek other options for a business that’s been at the center of steep losses over the past years.

If the Zurich-based bank can find a way for the unit to earn sustainable returns, that would be the preferred solution for shareholders, David Herro, the chief investment officer of Harris Associates, said in an interview Friday. But if it can’t be fixed within the next year or two, then options such as a sale, spin-off or merger must be explored, he said.

“This has been a problem child,” Herro, whose firm holds a 10% stake in the bank, said in a Bloomberg TV interview. “It sounds simple, but all they have to do is prevent the investment bank from losing money.”

The Swiss bank, which is on its fourth chief executive since 2015, is seeking to rebound from years of scandals and losses, many of them related to the securities and trading unit. Last month it announced a strategic shift and singled out a key investment banking unit for possible changes as it reallocates capital.

Harris Associates has owned Credit Suisse stock since the early years of this century, with the first 10 years of ownership proving to be very good. 

“What we should have done then was sold it,” Herro said. Instead, the firm bought more stock when the bank performed better than others during the 2008 financial crisis.

“You can’t keep doing the same thing they have been doing over the last decade and get zero results,” Herro said. “They have to put an end to it.”

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