NRG ENERGY, INC.

1. These shares were sold by Lightning Power Holdings, LLC, Thunder Generation LLC, and CCS Power Holdings, LLC (the Selling Stockholders) pursuant to an underwriting agreement dated March 2. 2026, among the Selling Stockholders, the Issuer, Barclays Capital Inc. and Citibank Global Markets Inc., at a price per share of $164, before underwriting discounts and commissions (the Secondary Offering). The Secondary Offering closed on March 4, 2026.

2. Also on March 4, 2026, the Selling Stockholders sold shares of the Issuer's Common Stock at a price of $164 to the Issuer pursuant to a Stock Repurchase Agreement dated as of February 27, 2026.

3. 3,782,093, 799,282, and 239,356 shares are held directly by Lightning Power Holdings, LLC, Thunder Generation LLC, and CCS Power Holdings, LLC, respectively. The reporting person is the investment advisor to the LS Power entities who may be deemed to beneficially own the securities held by the Selling Stockholders is LS Power Equity Advisors, LLC (LSP Advisors).

4. The reporting person, through its position, relationship and/or affiliation with the LS Power entities, may have shared voting and investment power with respect to the shares beneficially owned by the LS Power entities. As such, the reporting person may be deemed to have or share beneficial ownership of the shares beneficially owned by the LS Power entities.

5. The Issuer and the Selling Stockholders are parties to an Amended and Restated Voting Trust Agreement with Wilmington Savings Fund Society, FSB (the Trustee), pursuant to which the Selling Stockholders deposited 3,300,000 shares of Common Stock in the Project Hurricane Consideration Voting Trust 2026 (the Trust) and granted to the Trustee, subject to certain exceptions, voting rights with respect to such shares.