Shares of Butterfield Bank fell 20.8 per cent in Bermuda Stock Exchange trading.The $5 plunge on the trading of 500 shares left Butterfield at a 52-week low of $19. It also meant the bank’s BSX share price caught up with the decline of Butterfield’s US-listed shares.The bank moved in the opposite direction on Wall Street, gaining 86 per cent, or 4.7 per cent, to close on $19.12 on the New York Stock Exchange. BF&M Ltd fell 25 cents, or 1.4 per cent, to close on $17.70 as 7,900 shares changed hands.One Communications Ltd remained unchanged 0n $3.75 as 3,000 shares were traded.The Royal Gazette/BSX Index fell 226.79 points, or 12.6 per cent, to close on 1,572.56.Trading volume totalled 11,400 shares and turnover was $160,020.The BSX Insurance Index surged 61.3 points, or 5.26 per cent, to close on 1,226.93.