Gilead Sciences (GILD) is down more than 4% following another disappointing quarter for the company’s HCV franchise. It was the HCV franchise that drove GILD in 2014. However, pricing pressures have meant that HCV sales have started to slowdown since 2015.

In the second quarter, Harvoni sales dropped 28.9% on a year-over-year basis to $2.56 billion. Sovaldi sales, meanwhile, rose 5.2% to $1.36 billion.

Gilead lowered its net product sales guidance for 2016. The company now expects net product sales to be between $29.5 billion and $30.5 billion, compared to previous guidance range of $30 billion to $31 billion.

While the disappointment of HCV sales slow down is continuing to hurt GILD shares, I believe the market is continuing to ignore the strength of the HIV franchise. In the second quarter, HIV franchise sales rose to $3.1 billion from $2.7 billion. At current levels, I continue to believe that GILD is significantly undervalued. Even based on the reduced forecasts for 2016 net product sales, GILD only trades at just over 4x sales.