What's going on?

The biggest health insurer in the US, UnitedHealth, said that it is losing so much money by doing business on the Obamacare health-insurance exchanges (explained below) that it might cease to sell�insurance on them. This is important both politically and financially � and stocks of UnitedHealth and similar insurers were off by around 5%.

What does this mean?

The insurance exchanges were setup by President Obama�s Affordable Care Act (a.k.a. Obamacare) as a way for insurers to competitively provide health insurance to those that didn�t have it through other means (like their job). The problem appears to be that lots of people are only buying insurance once they are sick � which isn�t a profitable model for the insurance companies.

Why should I care?

1. The bigger picture: The �exchanges� are key to Obamacare. But apparently they aren�t financially viable for insurance companies. This might, effectively, be UnitedHealth firing a warning shot at the US government suggesting that it, somehow, make the exchanges economical.
2. For stocks: The exchanges are hurting health insurers more than investors realised, but� UnitedHealth is still going to make almost $6 billion of earnings in 2014. While health insurer stocks are selling off because they won�t make as much money as expected, they still have other major sources of revenue.