Butterfield Bank dropped 5.1 percent (seven cents) on The Bermuda Stock Exchange (BSX) yesterday.The bank traded 10,000 shares to close at $1.31.Argus Group Ltd also saw 700 shares change hands, but its share price held firm at $13.90.Overall the Index slipped 33.1 points (2.79 percent) to 1,154.55 with 10,700 shares worth $22,830 transacted.The BSX Insurance Index, however, was up 10 points (1.12 percent) at 900.