SECOND AMENDED AND RESTATED MIRANT SERVICES SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN SECOND AMENDED AND RESTATED MIRANT SERVICES SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

Exhibit 10.18

SECOND

AMENDED AND RESTATED

MIRANT SERVICES

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

SECOND AMENDED AND RESTATED

MIRANT SERVICES

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

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SECOND AMENDED AND RESTATED

MIRANT SERVICES

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

ARTICLE I

PURPOSE AND ADOPTION OF PLAN

1.1. Adoption . Mirant Services, LLC (f/k/a Southern Energy Resources, L.L.C.) hereby amends and restates for a second time the Mirant Services Supplemental Executive Retirement Plan, effective as of January 1, 2009. The Plan was originally adopted effective June 25, 1998. The Plan shall be an unfunded deferred compensation arrangement whose benefits shall be paid solely from the general assets of the Employing Companies.

1.2. Purpose . The Plan is designed to provide deferred compensation benefits primarily for a select group of management or highly compensated employees which are not otherwise payable under the Pension Plan as a result of the exclusion of incentive pay from certain definitions of earnings set forth under such plan.

ARTICLE II

DEFINITIONS

2.1. “ Accrued SERP Benefit ” shall mean the actuarially determined present value of a Participant’s SERP Benefit determined as of a given date.

2.2. “ Administrative Committee ” shall mean the committee appointed by the Board of Managers under Section 3.1 hereof to administer the Plan.

2.3. “ Affiliated Employer ” shall mean any corporation, other than the Company, which is a member of the controlled group of corporations of which Mirant Corporation is the common parent corporation, which the Board of Managers may from time to time determine to identify under the Plan.

2.4. “ Affiliated Employer Incentive Pay ” shall mean such incentive pay paid (or which would have been paid except for the deferral of such amounts under the Mirant Corporation Deferred Compensation Plan for Directors and Select Employees, the Mirant Corporation Deferred Compensation Plan, or any successor plan) to a Participant by an Affiliated Employer which the Administrative Committee shall from time to time identify as incentive pay under the Plan, including but not limited to any incentive pay paid under the Omnibus Plan, to the extent such payments do not exceed 200% of the Participant’s base pay (as determined for purposes of Section 2.4 herein); provided, however, any payment received by the Participant under the Mirant Services Supplemental Compensation Plan shall be specifically excluded.

2.5. “ Base Pay Percentage ” shall mean the percentage of a Participant’s base pay for purposes of Section 5.1(b)(2) hereof, as established by the Board of Managers upon the recommendation of the Administrative Committee for each Plan Year prior to the beginning of

such Plan Year. In the event that the Board of Managers does not consider the Base Pay Percentage for any particular Plan Year, the Base Pay Percentage for such Plan Year shall be deemed to be the Base Pay Percentage in effect for the immediately preceding Plan Year. The initial Base Pay Percentage for the Company’s Chief Executive Officer shall be ten percent (10%) and for all other Participants shall be fifteen percent (15%).

2.6. “ Beneficiary ” shall mean any person, estate, trust or organization entitled to receive any payment under the Plan upon the death of a Participant.

2.7. “ Board of Managers ” shall mean the Board of Managers of the Company.

2.8. “ Code ” shall mean the Internal Revenue Code of 1986, as amended from time to time.

2.9. “ Company ” shall mean Mirant Services, LLC, its successors and assigns.

2.10. “ Effective Date ” of this second and restated Plan shall mean January 1, 2009. The Plan was originally effective June 25, 1998 and was first amended and restated effective as of April 2, 2001.

2.11. “ Employee ” shall mean any person who is an employee of an Employing Company, excluding any person represented by a collective bargaining agent.

2.12. “ Employing Company ” shall mean the Company and any United States subsidiary or affiliate of Mirant Corporation, and any other subsidiary of Mirant Corporation, which the Board may from time to time determine to bring under the Plan and which shall adopt the Plan, and any successor of any of them.

2.13. “ Excess Benefit ” shall mean the “pension benefit” (as such term is defined in the Mirant Services Supplemental Benefit (Pension) Plan), if any, that is payable to a participant under the Mirant Services Supplemental Benefit (Pension) Plan, as amended from time to time.

2.14. “ Incentive Pay ” shall mean those short-term incentive awards, if any, paid (or which would have been paid except for the deferral of such amounts under the Mirant Corporation Deferred Compensation Plan for Directors and Select Employees, the Mirant Corporation Deferred Compensation Plan, or any successor plans) to a Participant under the terms of the Omnibus Plan and such other incentive awards as may be approved from time to time by the Board of Managers, to the extent such payments do not exceed 200% of the Participant’s base pay (as determined for purposes of Section 2.4 herein); provided, however, any payment received by the Participant under the Mirant Services Supplemental Compensation Plan shall be specifically excluded.

2.15. “ Omnibus Plan ” shall mean the Mirant Corporation 2005 Omnibus Incentive Compensation Plan, as amended from time to time.

2.16. “ Participant ” shall mean an Employee or former Employee who is eligible to participate in the Plan pursuant to Section 4.1 hereof.

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2.17. “ Payment Commencement Date ” shall mean, for each Participant, the January 1, April 1, July 1 or October 1 that immediately follows the later of (a) the date such Participant separates from service (within the meaning of Section 409A of the Code), b) the date such Participant reaches age 50, or (c) January 1, 2009.

2.18. “ Pension Plan ” shall mean the Mirant Services Pension Plan, as amended from time to time.

2.19. “ Plan ” shall mean the Second Amended and Restated Mirant Services Supplemental Executive Retirement Plan, as amended from time to time.

2.20. “ Plan Year ” shall mean the calendar year.

2.21. “ Resolution Date ” shall mean the first date on which all of the amount deferred with respect to a Participant under this Plan is reasonably ascertainable within the meaning of Treasury Regulation 31.3121(v)(2).

2.22. “ SERP Benefit ” shall mean the supplemental pension benefit described in Section 5.1 hereof.

2.23. “ Trust ” shall mean the Mirant Corporation Benefit Security Trust Agreement (adopted effective April 2, 2007).

Where the context requires, the definitions of all terms set forth in the Pension Plan shall apply with equal force and effect for purposes of interpretation and administration of the Plan, unless said terms are otherwise specifically defined in the Plan. The masculine pronoun shall be construed to include the feminine pronoun and the singular shall include the plural, where the context so requires.

ARTICLE III

ADMINISTRATION OF PLAN

3.1. Administrative Committee . The general administrative functions of the Plan shall be managed by the Administrative Committee appointed by the Board of Managers. The initial members of the Administrative Committee shall be the members of the Company’s Mirant Benefits Committee. Administrative Committee members shall serve at the pleasure of the Board of Managers and may be removed and appointed as the Board of Managers in its sole discretion shall determine.

3.2. Powers . The Administrative Committee shall administer the Plan in accordance with its terms and shall have all powers necessary to carry out the provisions of the Plan more particularly set forth herein. The Administrative Committee shall have the discretionary authority to interpret the Plan and shall determine all questions arising in the administration, interpretation and application of the Plan. Any such determination by it shall be conclusive and binding on all persons. It may adopt such regulations as it deems desirable for the conduct of its affairs. It may appoint such accountants, counsel, actuaries, specialists and other persons as it deems necessary or desirable in connection with the administration of this Plan, and shall be the agent for the service of process.

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3.3. Duties of the Administrative Committee .

(a) The Administrative Committee is responsible for the daily administration of the Plan. It may appoint other persons or entities to perform any of its fiduciary functions. The Administrative Committee and any su