(Bloomberg) -- Shares of two regional US banks tumbled Thursday after the companies said they were the victims of fraud on loans to funds that invest in distressed commercial mortgages, fueling concern that more cracks are emerging in the credit markets.Zions Bancorp sank 12% after it disclosed a $50 million charge-off for a loan underwritten by its wholly-owned subsidiary, California Bank & Trust, in San Diego. And Western Alliance Bancorp tumbled almost 11% after it said it made loans to the same borrower ...

Core Insights - Two regional US banks reported being victims of fraud related to loans for distressed commercial mortgages [1] Group 1: Company Impact - Zions Bancorp experienced a 12% decline in stock price after announcing a $50 million charge-off for a loan underwritten by its subsidiary, California Bank & Trust [1] - Western Alliance Bancorp's stock fell nearly 11% after revealing it had made loans to the same borrowers involved in the fraud [1] Group 2: Market Reaction - The disclosures from both banks led to significant stock price drops, indicating investor concern over the implications of the fraud on their financial health [1]