Medicaid, the government program for providing health insurance to low-income and disabled Americans, is the largest health insurer in the United States with more than 73 million enrollees. It is also the sector of the U.S. public health insurance system that relies most heavily on the tools of...

The Affordable Care Act Marketplaces were introduced in 2014 as part of a reform of the U.S. individual health insurance market. While the individual market represents a small slice of the U.S. population, it has historically been the market segment with the lowest rates of take-up and greatest...

Health insurers increasingly compete on their covered networks of medical providers. Using data from Massachusetts' pioneer insurance exchange, I find substantial adverse selection against plans covering the most prestigious and expensive "star" hospitals. I highlight a theoretically distinct...