If the economic setting turns gray, they are impervious to the business cycle.

FORBES: A good year for xenophobes

Mayor Vincent Gray, Victor Hoskins, the deputy mayor for planning and economic development, and several other D.

FORBES: Thoughts on China

"The two dominant price drivers of European carbon are political will and economic growth, and both are questionable at present, " said Matthew Gray, carbon analyst and trader at Jeffries in London.

WSJ: Europe's Carbon Market Trips on a New Proposal