Shares of First Republic Bank slumped early Friday as Wall Street stocks opened lower, a sign of lingering worries over the banking sector despite extraordinary protective measures by US authorities and private lenders. Near 1400 GMT, shares of First Republic were down about 17 percent, resuming a fall that paused Thursday when a consortium of major US banks said they would deposit $30 billion to shore up the embattled California lender. The move lower echoed the dynamic for Credit Suisse, another bank facing questions, which fell sharply Friday on the Swiss exchange. “The question becomes is that enough?” said Quincy Krosby of LPL Financial. Despite developments yesterday, there remain “questions about the strength of the underpinning of the financial system,” Krosby added. About 30 minutes into trading, the Dow Jones Industrial Average was down 0.8 percent at 31,998.79. The broad-based S&P 500 dropped 0.5 percent to 3,942.65, while the tech-rich Nasdaq Composite Index was flat at 11,720.27.