X0303 4 2010-12-03 0 0001126294 GenOn Energy, Inc. GEN 0001243150 JINES MICHAEL L 1000 MAIN STREET 12TH FLOOR HOUSTON TX 77002 0 1 0 0 EVP, Gen. Counsel & Corp. Sec. Common Stock 2010-12-03 4 F 0 52057 3.515 D 105940 D Time-Based Cash Units 2010-12-03 4 M 0 50000 0.00 D Common Stock 50000 0 D Performance-Based Cash Units 2010-12-03 4 M 0 18117 0.00 D Common Stock 18117 0 D The reporting person disposed of these shares to satisfy tax withholding obligations related to the vesting of restricted stock units in connection with the merger (the "Merger") involving Mirant Corporation and GenOn Energy, Inc., formerly known as RRI Energy, Inc. Each time-based cash unit is the economic equivalent of one share of GenOn Energy, Inc. common stock. The time-based cash units were paid in cash in connection with the Merger based on the fair market value per share of GenOn Energy, Inc. common stock on the date immediately preceding the closing date of the Merger. Each performance-based cash unit is the economic equivalent of one share of common stock of GenOn Energy, Inc. The performance-based cash units were paid in cash in connection with the Merger based on the fair market value per share of GenOn Energy, Inc. common stock on the date immediately preceding the closing date of the Merger. /s/ Michael L. Jines 2010-12-07