Benzinga's Top #PreMarket Gainers By: Benzinga via Benzinga May 01, 2014 at 08:08 AM EDT Merrimack Pharmaceuticals (NASDAQ: MACK) shares jumped 73.12% to $7.60 in pre-market trading after the company reported that MM-398 has ... Read More >> Related Stocks: AT&T Inc DIRECTV Willis Towers Watson Public Ltd Yelp Inc