We re-examine tacit collusion under a simple punishment rule in which firms match any lower price by their rivals, but otherwise leave their prices unchanged. We provide conditions under which this simple rule sustains collusion and is credible. Provided competition is imperfect, collusion can...

In government-sponsored health insurance, subsidy design affects market outcomes. First, holding premiums fixed, subsidies determine insurance uptake and average cost. Insurers then respond to these changes, adjusting premiums. Combining data from the first four years of the California ACA...