Bank Of America the banking giant, said on Tuesday that it was scaling back its investment banking operations, shedding an additional 650 jobs after suffering heavy trading losses from bad mortgage investments.

The layoffs will be on top of 500 jobs that were eliminated in mid-October, when Bank of America executives signaled plans for a retreat. Together, the cuts represent about 19 percent of the investment bank’s 5,900 employees.

Executives said that they would reduce coverage of certain investment banking customers and narrow the services it provides to corporate clients overseas. They are also narrowing their trading activities, scaling back their presence in packaging the mortgages and other complex securities that have been hit hardest by a tightening credit market.

Bank of America also plans to sell its prime brokerage unit, which faced steep competition and huge investment requirements. The hedge fund Citadel Investments, which has a big prime brokerage arm, has been reported to be interested in the business. Bank of America has received several inquiries, executives said, but no decision has been made.

While many analysts and other experts expected a more drastic retrenchment, the moves are still a blow to the bank’s plans to develop a top-tier investment bank.