Purpose: the purpose of the study is to determine the specifics of the impact of companies’statements about their perceived environmental actions on their stock prices on the developed and developing stock exchanges. The contradictory findings on the impact of corporate environmental announcements on stock prices and the low level of green production, especially in developing countries, make this research work relevant.Methods: the research methodology is based on event analysis and the examination of the impact of some environmental announcements on the quotations of both developed and developing stock exchanges.Results: the environmental approach to business operations, as compared to traditional operations, often requires additional financial resources, and many companies refuse to go green. This paper examines whether the market value of a company increases after the growth of its environmental orientation and whether this can be used as additional motivation for companies to carry out environmental activities. The work has shown that greening in a developed market is primarily driven by government policy, while in an developing market – by the desire to enter international product and capital markets, and that the directions of greening reflect global rather than national priorities. In the developed market, the impact of environmental announcements is observed only in isolated cases and can be both positive and negative. In the developing market, the significance of announcements is higher, and they lead to a short-term decline in exchange prices.Сonclusions and Relevance: it is concluded that it is seen necessary to improve markets’ regulatory and information space and to harmonize the interests of all participants to address environmental issues. The results will be of interest to investors, corporate managers, territorial governments, as well as specialists in green economy and behavioral finance.