Wall Street mixed post Fed; Alibaba, Google in focus By: CNBC.com News January 29, 2015 at 05:58 AM EST U.S. stock index futures signaled a mixed open on Thursday ahead of a major day of earnings from Wall Street's biggest tech firms. Read More >> Related Stocks: Alibaba Group Holding Ltd ConocoPhillips Nasdaq OMX Group Samsung Electronics Ltd Sentinelone Inc Cl A