US stocks finished a choppy session slightly lower as investors grappled with weakness in overseas equity markets and another drop in oil prices. At the closing bell, the Dow Jones Industrial Average and S&P 500 were both down 0.05pc, while the tech-rich Nasdaq Composite Index lost 0.36pc. "The market is trying to find a floor," said Alan Skrainka, chief investment officer at Cornerstone Wealth Management. "We still believe this volatility is going to continue until commodity prices settle down, and that hasn't happened yet." Concerns over the health of global banks also weighed on markets. John Cryan, the chief executive of Deutsche Bank, was forced to publicly claim the bank is “rock solid” following a dramatic drop in the troubled German giant’s share price. The British banker, who only joined Deutsche seven months ago, maintained that there was no reason to panic and called on his staff to spread that message to clients. “You can tell them that Deutsche Bank remains absolutely rock-solid, given our strong capital and risk position,” he said in a letter to employees. His plea was followed by Germany’s finance minister Wolfgang Schaeuble who took the unsual step of also trying to reassure investors in the lender. “I have no concerns about Deutsche Bank,” he said. Shares in Deutsche tumbled another 4.7pc on Tuesday. The bank’s shares fell to €13.26 and are now down 46pc since the start of the year and 58pc in the last six months. Last month the bank reported a €6.8bn (£5.3bn) loss for 2015. Deutsche has led the wider banking market down as fears spread over the profitability and financial stability of Germany’s biggest bank. Yesterday Swiss institution Credit Suisse’s shares were down by almost as much, plunging 7.75pc. Spooked investors also sold off shares in other banks, leaving Barclays down 5.2pc, BNP Paribas down 4.8pc and Italy’s Intesa Sanpaolo down 4.9pc.