Credit Suisse ($CS@Switzerland) dropped 21.5 percent in premarket trading after Saudi National Bank said it wouldn’t provide further financial help. Credit Suisse’s losses spread to the global banking sector. Bank of America ($BAC@US) lost 2.9 percent, Morgan Stanley ($MS@US) fell 3.2 percent, and Wells Fargo ($WFC@US) fell 4.2 percent in premarket trading. Regional banks fell following Tuesday’s rally. PacWest ($PACW@US) and Comerica ($CMA@US) lost 7.7 percent and 3.4 percent, respectively. KeyCorp ($KEY@US) fell 1.4 percent, Regions Financial ($RF@US) fell 4.2 percent, and Zions Bancorp ($ZION@US) lost 5.5 percent in premarket trading. Shares of San Francisco-based First Republic rallied, gaining 3.8 percent in premarket trading.