 Shares in Nomura Holdings Inc. NYSE: NMR and Credit Suisse Group AG NYSE: CS were both down more than 10 Monday morning after the banks said they face the potential loss of billions of dollars due to a hedge funds default on margin calls late last week. What Happened: Nomura issued a trading update Monday that highlighted a a significant loss arising from transactions with a U.S. client, adding that it is currently evaluating the extent of the possible loss. 