BlackRock C.E.O. Larry Fink: Climate Crisis Will Reshape Finance

In his influential annual letter to chief executives, Mr. Fink said his firm would avoid investments in companies that "present a high sustainability-related risk."

BlackRock's decision may give C.E.O.s license to change their own companies' strategy and focus more on sustainability, even if doing so cuts into short-term profits. Such a shift could also provide cover for banks and other financial institutions that finance carbon-emitting businesses to change their own policies.

Please provide an explanation on the above paragraph. Why can they change their own policy?