Corporate sustainability reporting initiatives have grown rapidly. Despite their recent significant expansion, the effects of environmental transparency programs on business, public policy, and society remain controversial. This report  examines how transparency affects business, emphasizing state-of-the-art research on how financial
markets respond to sustainability information. Established evidence shows that bad corporate environmental news is punished by the market. However, emerging evidence shows that, in some instances, superior environmental performance may also be punished by the market.