Get the DealBook newsletter to make sense of major business and policy headlines — and the power-brokers who shape them. __________ Financial stocks have just had their worst day since the February sell-off. Shares of banks in the S&P 500 were down 4.4 percent Tuesday, helping pull the S&P 500 down 3.2 percent. Bank of America, Morgan Stanley, JPMorgan Chase, Wells Fargo and Citigroup were each down more than 4 percent, while Goldman Sachs was off 3.8 percent. Behind the slide was the fall in...