The Royal Gazette/BSX Index closed unchanged on 1,597.44 on a day when no stocks traded on the Bermuda Stock Exchange.The US-listed shares of Butterfield Bank slumped 90 cents, or 4.12 per cent, to close at $20.94 on the New York Stock Exchange as 597,234 shares were traded.Butterfield last traded at $20 on the BSX.The BSX Insurance Index gained 38.25 points, or 3.34 per cent, to close on 1,183.88.