Shares of Argus Group Holdings Ltd saw unusually high trading volume on the Bermuda Stock Exchange.Argus gained two cents, or 0.8 per cent, to close on $2.56 on the trading of 85,575 shares.The insurer was the lone stock to trade on the BSX. The Royal Gazette/BSX Index fell 0.4 of a point, or 0.02 per cent to close on 1,825.35.The US-listed shares of Butterfield Bank fell 11 cents, or 0.43 per cent, to close on $25.39 on the New York Stock Exchange, as 114,775 shares were traded.Butterfield last traded at $24.70 on the BSX.The BSX Insurance Index surged 59.2 points, or 4.16 per cent, to close on 1,480.76.