U.S. stocks are now positive for this year at Thursday's closing bell. All the major markets ended up more than 1% with the Dow Jones Industrial rising 211 points. The equities market followed oil's recovering. Crude prices settled above $50 dollars a barrel with gains of better than 4%. M&A activity boosted investor sentiment. Pfizer (PFE) rose about 3% on news it will buy Hospira (HSP) in a huge deal. DuPont (DD) also led the blue chips' gains. The stock rose after being halted on news it appointed two new directors. The board's revamp comes as the chemicals company faces pressure to break itself up from activist investors.