Is Coal a 4-Letter Word?

Is coal a dirty word again? If you look at the coal sector’s performance yesterday — from the price of coal, to the coal companies themselves, and even to miners in general — anyone associated with the industry got covered in soot.

The Dow Jones U.S. Coal Index tumbled 14% yesterday, leaving investors who hold coal stocks perhaps feeling like canaries in a coal mine — wondering whether they should take flight.