Hartford Financial Services Group Inc. /zigman2/quotes/207281914/composite HIG -1.14% said Friday that it will no longer insure or invest in companies that generate more than 25% of their revenue from thermal coal mining, or more than 25% of their energy production from coal. The Hartford said it will also no longer insure and invest in companies that derive more than one-quarter of their revenue from the extraction of oil from tar sands. "The world needs affordable, accessible energy to support global economic progress and, at the same time, action is needed to mitigate the impact such activity has on our climate," said Chief Executive Christopher Swift. Shares of Arch Coal Inc. /zigman2/quotes/203542275/composite ARCH +3.33% fell 3.3% in afternoon trading. Among other companies in the coal business, Peabody Energy Corp.'s stock /zigman2/quotes/203600175/composite BTU +15.43% eased 0.6%. Year to date, shares of Arch Coal have tumbled 15% and Peabody Energy plunged 70%, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -1.04% has climbed 29%.