Austin Frakt writing on The AcademyHealth Blog:
Less competition among insurers can help reduce provider prices, but with a side-effect of increasing premiums and lack of coverage. Rate regulation can help counter the latter. Another approach is to increase the bargaining clout of consumers, e.g., by aggregating them in exchanges. This would make the individual market behave a bit more like the group market, for which Bates, Hillard, and Santerre found no relationship between insurer market concentration and coverage.