The Royal Gazette/BSX Index closed unchanged on 1,784.44 as no shares traded on the Bermuda Stock Exchange.The US-listed shares of Butterfield Bank fell 93 cents, or 3.81 per cent, to close on $23.46 on the New York Stock Exchange, as 140,374 shares changed hands.Butterfield last traded on the BSX at $24.05.The BSX Insurance Index fell 10.41 points, or 0.75 per cent, to close on 1,382.6.Separately, Butterfield Bank said that during last month it purchased for treasury 425,000 common shares at an average price of $25.29 per share.