 Shares of Signature Bank SBNY, -13.07 sank 12.8 in afternoon trading Monday, enough to pace the SP 500s SPX, -3.23 decliners, as the New York-based bank was hurting from a broad selloff in the financial sector and from the plunge in bitcoin BTCUSD, -14.83 toward an 18-month low. The stock was headed for the biggest one-day selloff since it tumbled 13.0 on March 20, 2020, and the lowest close since Feb. 1, 2021. 