Butterfield Bank closed down 5.4 percent on the Bermuda Stock Exchange (BSX) yesterday.The bank’s shares closed down 6 cents to $1.06 on a volume of 77,861.Overall the BSX closed down 28.44, or 2.74 percent, to finish at 1,009.70.The BSX Insurance Index closed up 3.00, or 0.30 percent, to finish at 1017.00.