Shares of GlaxoSmithKline GSK, +0.36% were down 0.05% in premarket trading on Monday after the Food and Drug Administration late on Friday approved its HIV drug Tivicay as a treatment for infants and children. Tivicay is the company's second-best selling drug in its HIV portfolio. About 2,200 children in the U.S. had been diagnosed with HIV in 2016, according to statistics provided by the Centers for Disease Control and Prevention. GSK's stock has gained 14.9% since the start of the year. The S&P 500 SPX, -0.56% is down 5.8% year-to-date. The FDA is granting the approval of Tivicay and Tivicay PD to ViiV Healthcare.