(Reuters) – Gilead Sciences Inc on Monday reported fourth-quarter results that fell short of Wall Street estimates as sales of its flagship hepatitis C drugs continued to slide due to competition for a smaller pool of patients.

The drugmaker also estimated 2019 product sales of $21.3 billion to $21.8 billion. Wall Street analysts, on average, had forecast 2019 revenue of $21.8 billion, according to IBES data from Refinitiv.

Gilead shares fell 3 percent to $67.83 in after hours trading.

Excluding one-time items, Gilead said it earned $1.44 per share in the fourth quarter. Analysts expected $1.70.

Quarterly net income was $3 million, or nil per share, due to an impairment charge related to an acquisition. That compared with a net loss of $3.9 billion, or $2.96 per share, a year earlier. Revenue for the quarter slipped to $5.8 billion from $5.9 billion.

Fourth-quarter sales of Gilead’s HIV drugs rose to $4.1 billion from $3.4 billion. But sales of hepatitis C drugs fell sharply to $738 million from $1.5 billion in the same period of 2017.

The drop was largely expected as these newer drugs have cured many patients with the liver disease and rival products have seized market share.