GENEVA — Scarred by scandals and losses, Swiss bank UBS on Tuesday unveiled a plan to overhaul its global operations that will see it cut thousands of jobs as it drops risky trading activities and restructures its investment banking unit.

Switzerland’s biggest bank has for years been trying to reshape its business and clean up its image as it tries to recover from a damaging U.S. tax evasion dispute, a scandal over unauthorized trades and a slew of bad investments.

Tuesday’s plan represented a sudden acceleration in this turnaround effort.

UBS AG will cut 10,000 jobs, on top of 3,500 shed last year, as it drops out of trading in fixed income — which includes bonds and currencies — and rejiggers its investment banking.

It will cut 3,000 of those jobs at its U.S. operations along Interstate 95 in Stamford, Conn., near New York City. Another 4,500 will be axed in London, with the remaining 2,500 in Switzerland.

“This decision has been hard but necessary to create a UBS that is fit for the future,” said chief executive Sergio Ermotti.

The need to restructure the investment banking unit was apparent in the bank’s third-quarter earnings, released Tuesday. UBS suffered a $2.31 billion loss in the July to September period, down from a profit of $1.1 billion the year before, mainly due to a loss of $3.3 billion in investment banking. “It can’t get better than this point for us to act,” Ermotti said.

With 63,745 employees in 57 countries, UBS said it aims for a headcount of 54,000 in 2015.

Boston University finance expert Mark Williams said UBS “should be applauded for exiting fixed-income trading and refocusing on its core competencies.”

UBS is also one of several global banks being investigated in the U.S. and other countries for alleged rigging of a benchmark interest rate known as Libor, or London Interbank Offered Rate.

The investment banking unit, meanwhile, is struggling to meet new global rules for banks’ capital reserves.

The new rules require banks to increase the amount of capital they hold to offset risky assets on their balance sheets. That hurts profitability — in the third quarter, UBS booked a charge of 863 million francs to account for these new rules.