Shares of Butterfield Bank slumped 8.7 per cent in light trading on the Bermuda Stock Exchange.The bank dipped $2.60 to close on $27.25 on the trading of 526 shares.Butterfield’s US-listed shares also fell 43 cents, or 1.53 per cent, to close on $27.72 on the New York Stock Exchange amid a broad-based market slump.Ascendant Group Ltd, parent company of power utility Belco, fell 50 cents, or 1.5 per cent, to close the day on $33. The company is awaiting regulatory approval for a proposed $36-a-share takeover by Algonquin Power and Utility Corp, a deal previously approved by Ascendant shareholders.Butterfield’s dip weighed heavily on The Royal Gazette/BSX Index, which fell 121.76 points, or 5.86 per cent, to close on 1,956.74.BSX trading volume was 3,526 shares, while turnover totalled $133,333.50.The BSX Insurance Index fell 42.91 points, or 2.44 per cent, to close on 1,713.34.