A benchmark index used in the banking industry and by investors to track the performance of banks. The index was created and is traded by the Philadelphia Stock Exchange. It also is referred to as the bank index, or BK, which is its trading symbol. The BKX is a capitalization-weighted index composed of 24 geographically diverse stocks representing national money center banks and leading regional institutions. BKX is based on one-tenth of the value of the Keefe, Bruyette & Woods Index (KBWI). Founded in 1962, Keefe, Bruyette & Woods is recognized as a banking industry authority. The index was initiated at the time of the firm’s founding and was calculated retroactively to 1947. The index is evaluated at least annually by Keefe, Bruyette & Woods to assure that the composition is highly representative of the banking industry. Options trading began on September 21, 1992.