Credit Suisse notched up 5.3 billion Swiss franc (€3.3 billion) of credit-related writedowns in the first quarter, causing a bigger-than-expected loss.
The first-quarter loss was 2.1 billion francs (€1.3 billion).
It was the bank's first quarterly loss in five years.
"We substantially reduced our exposures to affected areas and we will continue to do so in a disciplined fashion," Chief Executive Brady Dougan said in a statement.
CS, which relies heavily on wealth management for its income, said in March it was unlikely to post a profit in the first quarter because of rocky markets and a deliberate mispricing of credit assets by a group of traders.
It said it had reduced its risk exposure by 41 per cent in leveraged finance and by 25 per cent in commercial mortgages.
Net new money inflows into the key wealth management business were 13.5 billion francs (€8.4 billion) in the first quarter, roughly in line with average expectations.
The steady inflow is a sign wealthy clients are still flocking to the bank despite problems from the credit crisis in its investment bank.
Credit Suisse stock is trading at around eight times expected 2009 earnings, roughly in line with the sector average. Rival UBS is trading at a 10 times multiple.