Shares of biopharma giant Gilead Sciences (NASDAQ:GILD) were up today after it announced a strong quarter, which included revenue doubling to $5 billion and earnings per share tripling from $0.43 to $1.33.

Most of the company's strength this quarter came from its hepatitis C drug Sovaldi. Sales of the drug hit $2.3 billion this quarter, which was incredible considering it was the first full quarter the drug was on the market. It also didn't hurt that sales of Stribild, Gilead's HIV pill, were up 134% year-over-year.

So should investors get in on the action? On today's Stock of the Day, Motley Fool analyst Michael Douglass says Gilead is worth watching, but it's important to be aware of the risks. One of his concerns is payer pushback, a very real threat to Gilead's hit drug Sovaldi considering that a 12-week treatment costs $84,000. Another thing Michael is keeping his eyes on is the competition--AbbVie and Enanta Pharmaceuticals both have products that should hit the market soon, while Bristol-Myers Squibb and Merck both have some competing products in their pipelines as well. 

Mark Reeth and Michael Douglass have no position in any stocks mentioned. The Motley Fool recommends Gilead Sciences. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.