This paper shows that regulatory actions can work as an instrument to correct the shortcomings of the private health insurance market. However, despite rules that defend both competition and consumer rights, these actions can, paradoxically, bring about a more marked concentration of the market if the power of the oligopolies is not challenged. to critique this sort of management, we first discuss the political context in which the Agência Nacional de Saúde Suplementar – ANS (National Supplementary Health Agency) arose, and describe the nature of the economic crisis facing the market. Considering these issues, we suggest an alternative proposal, in which the Agency would play a key role in overcoming the crisis, particularly by supporting public health principles and reducing the price of health insurance. We finally argue for the institutional reform of the market, restoring the meaning of the Agency's rules and preventing the ANS from falling under the power of the oligopolies.