Despite weaker-than-expected PPI statistics, investor optimism kept US stock futures trading marginally lower on Wednesday night. As of 6:35 p.m. ET (11:35 p.m. GMT), Nasdaq 100 Futures had dropped 0.2%, while Dow Jones and S&P 500 Futures had each dropped 0.1%. Cisco Systems Inc. (NASDAQ:CSCO) fell 10.7% in after-hours trading after revealing EPS of $1.11 …