The September contract on the FTSE 20 index was trading at a discount 0.36 pct in the Athens Derivatives Exchange on Wednesday, with turnover falling to 33.586 million euros. Volume on the Big Cap index totaled 8,940 contracts, worth 25.625 million euros, with 27,804 open positions in the market. Volume in futures contracts on equities totaled 21,064 contracts worth 7.962 million euros, with investment interest focusing on National Bank's contracts (7,193), followed by Eurobank (2,630), Alpha Bank (2,450), Piraeus Bank (1,818), Bank of Cyprus (1,366), ATEbank (945), Ellaktor (593) and OTE (581).