Shares of NRG Energy Inc. NRG rose 0.9% into record territory in premarket trading Monday, after the energy utility said Chief Executive Officer Mauricio Gutierrez has left the company after being named CEO eight years ago, and after 19 years with the company. The company also said it would add four independent directors to its board, all as part of a cooperation agreement with activist investor Elliott Investment Management. The leadership change comes after Elliott in June again called for the ouster of Gutierrez as CEO, with the hedge fund saying it believed Gutierrez had “lost the confidence of the core investor…