The Bermuda Stock Exchange closed down last week, dropping 1.86, or 0.17 percent, to end at 1,090.08.Butterfield Bank shares closed at $1.27 on a volume of 41,696.Butterfield Preference Shares closed up 1.2 percent, or $15, to end at $1,230.KeyTech closed down 15 cents, or 2.4 percent, to finish the week at $6 as 2,000 shares changed