The stock market started the new week on a sluggish note Monday, and the broadest-based market benchmarks gave up ground as the Dow fell further away from the 20,000 mark. Even though the Nasdaq Composite climbed to new highs, a $2 per barrel plunge in the price of oil to fall below $53 weighed on sentiment. Even with the pause in the upward trend, some stocks posted solid gains, and Ariad Pharmaceuticals (NASDAQ: ARIA), VCA (NASDAQ: WOOF), and Exact Sciences (NASDAQ: EXAS) were among the best performers on the day.