Stocks slump as Credit Suisse selloff reignites bank worries

Stocks are tumbling on Wall Street Wednesday as worries about the strength of banks worsen on both sides of the Atlantic Ocean. 

The Dow was down 503 points, or 1.6%, 31,652 as of 11:25 a.m. Eastern time, the broader S&P 500 fell 1.4% and the tech-heavy Nasdaq Composite dropped 1%. Markets in Europe slumped even further as shares of Switzerland's Credit Suisse tumbled to a record low.

The Switzerland-based Wall Street bank tanked following reports that its top shareholder will no longer pump more money into the struggling firm. Saudi National Bank representatives said they could not shore up their investments in Credit Suisse, citing regulatory concerns.