Energy companies failed to list more than two out of every five fracked wells in eight U.S. states from April 11, 2011, when FracFocus began operating, through the end of last year, according to data compiled by Bloomberg. The gaps reveal shortcomings in the voluntary approach to transparency on the site, which has received funding from oil and gas trade groups and $1.5 million from the U.S. Department of Energy...Oil and gas executives say the FracFocus website helps eliminate the need for any new federal oversight that might unify the regulatory approach. [refers to Apache, Royal Dutch Shell, Chesapeake Energy, ConocoPhillips, Exxon Mobil, Concho Resources, SandRidge Energy, QEP Resources, Continental Resources, Marathon Oil, EQT]