Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This study theoretically examines green portfolio standards with monetary penalties in an oligopoly market. We find that green portfolio standards attain first-best optimality if the purpose of the government is to restrict non-green products (i.e., unless the negative externality of gray products is too small), whereas they are inefficient policy tools if the purpose is to promote green products.