Shares of Gilead Sciences tumbled more than 8 percent on Wednesday after the drugmaker gave a weak sales forecast for its hepatitis C drugs.
On Tuesday, Gilead said in a fourth-quarter earnings release it predicts 2017 hepatitis C drug sales of between $7.5 billion and $9 billion, much lower than the $12 billion Wall Street had expected.
Hepatitis C is a disease that causes inflammation of the liver that can lead to liver failure.
The company also said it sees full-year net product sales of between $22.5 billion and $24.5 billion, compared with $30 billion in 2016.
"This market has been full of surprises," Gilead Chief Operating Officer Kevin Young said on a conference call, according to Reuters. "It surprised us on the way up, and it is surprising us in some ways with the dynamics coming down."
Despite the weak forecast, Gilead beat Street forecasts by 9 cents a share, with adjusted quarterly profit of $2.70 per share, led by sales of its hepatitis C drugs. The drugmaker's revenue also beat at $7.3 billion versus the $7.15 billion expected by Thomson Reuters estimates.
Separately, the company announced a 10 percent dividend increase.
The stock has fallen 21 percent in the past 12 months.
—Reuters contributed to this report.