Shares of Gilead Sciences (NASDAQ:GILD) were up nearly 4% today ahead of its earnings call after market close. Sales of its drug Sovaldi are absolutely crushing expectations, and Baird has recently upgraded the stock to "outperform" and given it a price target of $103.

In this video, Motley Fool health-care analyst David Williamson looks at Sovaldi sales and how much Gilead stands to benefit, and also how this may be a rising tide lifting other boats, including AbbVie (NYSE:ABBV).