boosted by gains in bank sector stocks. The exchange's index yesterday gained 18.14 points, closing at an all-time high of 1,285.69 on a volume of 53,604 shares valued at $841,651.13.

The previous high was 1,278.91 set on July 16. Since the start of this year the index has risen by 367.30 points, or about 40 percent.

Seven issues traded, four gaining, three unchanged in value. Bank of Butterfield gained 50 cents to close at $14.50 on a volume of 37,716, matching its 52 week high. Bank of Bermuda gained 25 cents to close at $26 on a volume of 6,583. Bermuda Home gained 50 cents to close at $8.50 on a volume of 1,012.

Bermuda Telephone Co. Ltd. gained 5 to close at $31 5 on a volume of 2,150.

Trading unchanged were the Bermuda Commercial Bank at $5 1 on a volume of 1,200, Kentucky Fried Chicken at $4 on a volume of 3,000, and Belco Holdings at $23 on a volume of 1,943.