Shares of Butterfield Bank surged 15 per cent in light trading on the Bermuda Stock Exchange.The bank advanced $3 to close on $23, as 500 shares changed hands.Butterfield’s US-listed shares slid 35 cents, or 1.55 per cent, to close on $22.24 on the New York Stock Exchange, on lighter than average volume of 208,504 shares.Ascendant Group Ltd, parent company of Belco, was the only other stock to trade on the BSX. The utility owner was unmoved on $31 as 2,050 shares traded.Butterfield’s advance spurred a gain of 134.92 points, or 8.46 per cent for The Royal Gazette/BSX Index, which closed on 1,728.97.The BSX Insurance Index gained 56.62 points, or 4.67 per cent, to close on 1,267.98.