Citi analyst Robyn Karnauskas upgraded Gilead Sciences (GILD) to Buy from Neutral and raised her price target for the shares to $103 from $81. The drugmaker closed yesterday up $3.34 to $88.80.

Tax reform could lower the company's tax rate to 22% in 2018 versus prior estimates of 28%, Karnauskas tells investors in a research note. The analyst also raised her nonalcoholic steatohepatitis and JAK-1 probability of success estimates to 50% with both Phase 3 trials expected in the next 12 months.

Further, Karnauskas expects Gilead's hepatitis C virus business to stabilize by mid-2018.