A group of US investors with more than $200 billion in assets have blacklisted 10 companies, including the oil giant ExxonMobil, the financial services group Wells Fargo and the utility TXU, for not doing enough to respond to global warming, in a sign of increasing shareholder activism on environmental issues. The group also includes: Dominion Resources, Allegheny Energy, Massey Energy, Consol Energy, ACE, ConocoPhillips and  Bed Bath & Beyond.