The U.S. rating company said it will monitor the U.S. investigations closely, the outcome of which could reflect significantly weaker corporate governance practices at the Indian conglomerate.

The change in the outlook of the seven Adani Group companies, will likely weaken Adani Group's access to funding and increase its capital costs, Moody's wrote in its note.

Fitch says the ratings reflect "increased corporate governance risk and potential contagion risk" that could affect the funding access of Fitch-rated entities

Sri Lanka is weighing U.S. bribery accusations against Adani Group and Fitch put some company bonds on a watch list for a possible downgrade, as fallout widens from indictments of some key executives of the Indian conglomerate.

Dollar bonds of Adani Group’s ports business may be cut to speculative grade after US prosecutors brought charges of alleged bribery against executives of the conglomerate, Fitch Ratings said Tuesday.