 Houghton Mifflin Harcourt Co NASDAQ:HMHC gapped up prior to trading on Friday . The stock had previously closed at 2.78, but opened at 2.35. Houghton Mifflin Harcourt shares last traded at 2.64, with a volume of 1,614,225 shares changing hands. A number of brokerages have issued reports on HMHC. BidaskClub upgraded Houghton Mifflin Harcourt from ... 