Longtime shale boss and North Texas energy magnate Scott Sheffield said he’s no longer interested in joining Exxon Mobil Corp.’s board after the U.S.

Two major oil and gas executives are now allowed to join Chevron and Exxon's board of directors — but only one might be interested.

The Federal Trade Commission said Tuesday that Scott Sheffield, founder and former chief executive of Pioneer Natural Resources, would not be allowed to directly challenge its order blocking him from Exxon Mobil's board,