KeyTech tumbled 54 cents (9.31 percent) on the Bermuda Stock Exchange to close at $5.26 with 21,150 shares trading. Argus Group also slid 30 cents (6.66 percent) to close at $4.20 with 1,000 shares trading. Butterfield Bank dropped one cent (.94 percent) to close at $1.05 with 150,400 shares trading.Overall, the BSX closed at 992.86, down 16.84 points (1.67 percent) with 172,550 shares trading worth $279,787.