Do insurers respond to active purchasing? Evidence from the Massachusetts health insurance exchange

Health insurance markets face continued challenges with high premiums and limited insurer competition. We describe a unique set of "active purchasing" policies used by Massachusetts' pioneer health insurance exchange to shape the rules of competition and reward lower-price insurers with additional customers. We provide evidence that these policies significantly influenced insurer pricing. Between 2010 and 2013, over 80% of insurer prices were set exactly at or within 1% of pricing thresholds created by active purchasing policies. A key "limited choice" policy was associated with a 16%-20% reduction in average insurance prices relative to comparison markets in 2012-2014. Insurers achieved these price cuts partly through cost reductions via narrower provider networks and partly through reduced profit margins.