On Tuesday's edition of Market Checkup, Motley Fool health-care analyst David Williamson looks at the biggest winners and losers in health-care stocks today.

Bristol-Myers Squibb (NYSE:BMY) took a hit recently, when it was unclear about its timeline for advancing its lead immuno-oncology drug candidate Nivolumab. While investors are excited about how this may pair up with Bristol's already approved drug Yervoy, management is taking a cautious pace while it tests out a number of different drug pairings. This delay has not only put doubt about the pairing in the mind of investors, but it has also given Merck (NYSE:MRK), which has a similar drug in development that would be a direct competitor, a chance to strike.

In this segment, David breaks this competitive race down for investors and discusses what to watch with these two companies in this space.

David Williamson owns shares of Merck. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.