A big rally on Wall Street Monday fueled by the weakness in the U.S. dollar. Stocks are back in the black for the year after the Dow Jones Industrial average gained 228 points. Crude slipped again to settle at $43.88 a barrel. DuPont (DD) was blue chip's biggest decliner. Shares fell more than 4% after being hit with a double blow. The stock was downgraded at BofA Merrill Lynch to an UNDERPERFORM from BUY rating. This comes amid an ongoing proxy fight with activist investor, Trian Fund Management. Sealing the deal had a couple of drugmakers higher. Valeant Pharmaceuticals (VRX) agreed to buy Salix Pharmaceuticals (SLXP) for $173 a share. Elon Musk's tweet saying Tesla's (TSLA) Model S was about to 'end range anxiety' drove its stock more than 3% higher.