On some negative news about one of its investigational programs, the stock of pharmaceutical company Gilead Sciences (GILD -2.54%) took some hits on Tuesday. Investors traded it down by more than 2%, comparing unfavorably to the 0.6% gain of the benchmark S&P 500 (^GSPC 0.55%). The FDA puts on the red lightThat morning, the U.S. Food and Drug Administration (FDA) ordered a halt to Gilead's testing of a two-drug combination to treat human immunodeficiency viruses (HIV), the cause of acquired immunodeficiency ...