trading on the Bermuda Stock Exchange yesterday. The index slipped 2.37 points closing at 934.73. Belco was off 50 cents at $19 on volume of 3,079 while Bank of Bermuda fell 25 cents closing at $17 on 3,970. Bank of Butterfield advanced 25 cents closing at $9.50 on 1,600. Bermuda Home was unchanged at $7.875 on 88.