Merck Gains on Ebola Vaccine News Despite Dow's 331 Point Drop

Crude realities hit stock traders with a massive sell-off on Wall Street Monday. The Dow tanked 331 points. The S&P 500 and Nasdaq also closed sharply lower. Oil prices struggled to settle, just above $50 a barrel after dipping below that psychological level during the session. Large-cap oil companies Exxon Mobil (XOM), Chevron (CVX) and BP (BP) took a nose-dive. But it was the small-cap energy stocks that got hit the hardest. Precision Drilling (PDS) and Oasis Petroleum (OAS) lost more than 9%. Pioneer Energy (PES) gave up 8%. American automakers also slid with Ford (F) losing almost 4%. General Motors (GM) also fell after reporting mixed sales for December. But Merck (MRK) was one of the bright spots and the blue chips' biggest gainer. Shares rose on news the clinical trial of its Ebola vaccine is resuming.