This episode of The Motley Fool's Market Checkup is dedicated to the world's largest pure-play biotech stock, Gilead Sciences (NASDAQ:GILD)Market Checkup gives a full examination of Gilead's second-quarter results, takes a closer look at the company's current product portfolio, and analyzes the future drugs that have investors excited about the stock's future.

In this video, health-care analysts David Williamson and Max Macaluso drill down on Gilead's core franchise of HIV drugs. Watch and find out why Gilead put its top seller at risk of losing sales, why that would actually be a good thing for the biotech, and whether a new competitor from a Big Pharma partnership could disrupt the market.