Stock futures were modestly higher in premarket trading Wednesday, looking to bounce back after a sell-off the prior day. Futures of the Nasdaq, S&P 500 and Dow Jones industrial average were all up 0.2%. The major indexes slid more than 1% Tuesday. Facebook (FB) was up 0.3% in premarket activity. The stock is trading below the 50-day moving average as it tries to build the right side of a base.