Microsoft, Rackspace fall; Groupon rises By: MarketWatch May 09, 2013 at 10:57 AM EDT Microsoft slips on report that it has offered to buy Nook assets. Rackspace also falls on disappointing results. But Groupon rises after beating estimates. Read More >> Related Stocks: Activision Blizzard Barnes & Noble Facebook Google, Inc. Groupon Cl A Microsoft PHLX Semiconductor Sector Index Yahoo