In this video, Motley Fool health care analyst David Williamson breaks down the market's big reaction today to President Barack Obama's reelection, and talks about how it effects industries in the health care sector. As Obama's Affordable Care Act is now almost certain to come into full effect during his second term, many insurers are taking a hit today, as they will no longer be able to discriminate based on pre-existing conditions in the years to come.

Medicaid insurers, however, have seen a boost today, as they expect to add millions of customers as Obama goes into his second term. You will want to keep an eye on both of these types of insurers as Obamacare-related developments continue to unfold.

David Williamson has no positions in the stocks mentioned above. Follow him on Twitter @MotleyDavid. The Motley Fool owns shares of UnitedHealth Group and WellPoint. Motley Fool newsletter services recommend UnitedHealth Group and WellPoint. 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.