X0306 4 2020-05-07 0 0001692819 Vistra Energy Corp. VST 0001728921 MUSCATO STEPHEN J 6555 SIERRA DRIVE IRVING TX 75039 0 1 0 0 EVP & Chief Commercial Officer Common Stock 2020-05-07 4 F 0 2469 17.95 D 88622 D This transaction represents the withholding by the Issuer of shares to pay taxes in connection with the vesting of restricted stock units. The timing and amount of the transaction were determined by the terms of the applicable restricted stock unit award and were not within the control of the Reporting Person. The number of securities shown to be beneficially owned following the transaction being reported in this Form 4 reflects an adjustment downward by 7,530 shares of common stock due to a previous clerical error in calculating the amount of securities beneficially owned in the Form 4 filed on May 10, 2019, which calculation error was also reflected in the three Forms 4 subsequently filed. /s/ Stephanie Zapata Moore, as Attorney-in-Fact 2020-05-11