10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

x	Quarterly report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
	For the Quarterly Period Ended: June 30, 2013
o	Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

GenOn Energy, Inc.

(Exact name of registrant as specified in its charter)

75-0655566 (I.R.S. Employer Identification No.)

Commission File Number: 001-16455

GenOn Americas Generation, LLC

(Exact name of registrant as specified in its charter)

51-0390520 (I.R.S. Employer Identification No.)

Commission File Number: 333-63240

GenOn Mid-Atlantic, LLC

(Exact name of registrant as specified in its charter)

58-2574140 (I.R.S. Employer Identification No.)

Commission File Number: 333-61668

Delaware (State or other jurisdiction of incorporation or organization)	(609) 524-4500 (Registrants' telephone number, including area code)
211 Carnegie Center, Princeton, New Jersey (Address of principal executive offices)	08540 (Zip Code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. (As a voluntary filer not subject to filing requirements, the registrant nevertheless filed all reports which would have been required to be filed by Section 15(d) of the Exchange Act during the preceding 12 months had the registrant been required to file reports pursuant to Section 15(d) of the Exchange Act solely as a result of having registered debt securities under the Securities Act of 1933.)

GenOn Energy, Inc.	o	Yes	o	No
GenOn Americas Generation, LLC	o	Yes	o	No
GenOn Mid-Atlantic, LLC	o	Yes	o	No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

GenOn Energy, Inc.	x	Yes	o	No
GenOn Americas Generation, LLC	x	Yes	o	No
GenOn Mid-Atlantic, LLC	x	Yes	o	No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

	Large accelerated filer	Accelerated filer	Non-accelerated filer	Smaller reporting company
GenOn Energy, Inc.	o	o	x	o
GenOn Americas Generation, LLC	o	o	x	o
GenOn Mid-Atlantic, LLC	o	o	x	o
			(Do not check if a smaller reporting company)

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

GenOn Energy, Inc.	o	Yes	x	No
GenOn Americas Generation, LLC	o	Yes	x	No
GenOn Mid-Atlantic, LLC	o	Yes	x	No

Each Registrant’s outstanding equity interests are held by its respective parent and there are no equity interests held by nonaffiliates.

Registrant	Parent
GenOn Energy, Inc.	NRG Energy, Inc.
GenOn Americas Generation, LLC	NRG Americas, Inc.
GenOn Mid-Atlantic, LLC	NRG North America LLC

This combined Form 10-Q is separately filed by GenOn Energy, Inc., GenOn Americas Generation, LLC and GenOn Mid-Atlantic, LLC. Information contained in this combined Form 10-Q relating to GenOn Energy, Inc., GenOn Americas Generation, LLC and GenOn Mid-Atlantic, LLC is filed by such registrant on its own behalf and each registrant makes no representation as to information relating to registrants other than itself.

NOTE: WHEREAS GENON ENERGY, INC., GENON AMERICAS GENERATION, LLC AND GENON MID-ATLANTIC, LLC MEET THE CONDITIONS SET FORTH IN GENERAL INSTRUCTION H(1)(a) AND (b) OF FORM 10-Q, THIS COMBINED FORM 10-Q IS BEING FILED WITH THE REDUCED DISCLOSURE FORMAT PURSUANT TO GENERAL INSTRUCTION H(2).

TABLE OF CONTENTS

CAUTIONARY STATEMENT REGARDING FORWARD LOOKING INFORMATON		2
GLOSSARY OF TERMS		3
PART I — FINANCIAL INFORMATION		5
	Item 1 — CONDENSED CONSOLIDATED FINANCIAL STATEMENTS AND NOTES	5
	Item 2 — MANAGEMENT'S NARRATIVE ANALYSIS OF THE RESULTS OF OPERATIONS AND FINANCIAL CONDITION	41
	Item 3 —QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK	54
	Item 4 — CONTROLS AND PROCEDURES	54
PART II — OTHER INFORMATION		55
	ITEM 1 — LEGAL PROCEEDINGS	55
	ITEM 1A — RISK FACTORS	55
	ITEM 2 — UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS	55
	ITEM 3 — DEFAULTS UPON SENIOR SECURITIES	55
	ITEM 4 — MINE SAFETY DISCLOSURES	55
	ITEM 5 — OTHER INFORMATION	55
	ITEM 6 — EXHIBITS	56
	SIGNATURES	57

1

CAUTIONARY STATEMENT REGARDING FORWARD LOOKING INFORMATION

(GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

This Quarterly Report on Form 10-Q includes forward-looking statements within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act. The words "believes," "projects," "anticipates," "plans," "expects," "intends," "estimates" and similar expressions are intended to identify forward-looking statements. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause the Registrants’ actual results, performance and achievements, or industry results, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. These factors, risks and uncertainties include the factors described under Item 1A - Risk Factors, in Part I, Item 1A of the Registrants' Annual Report on Form 10-K for the year ended December 31, 2012, including, but not limited to, the following:

• General economic conditions, changes in the wholesale power markets and fluctuations in the cost of fuel;

• Volatile power supply costs and demand for power;

• Hazards customary to the power production industry and power generation operations such as fuel and electricity price volatility, unusual weather conditions, catastrophic weather-related or other damage to facilities, unscheduled generation outages, maintenance or repairs, unanticipated changes to fuel supply costs or availability due to higher demand, shortages, transportation problems or other developments, environmental incidents, or electric transmission or gas pipeline system constraints and the possibility that the Registrants may not have adequate insurance to cover losses as a result of such hazards;

• The effectiveness of the Registrants’ risk management policies and procedures, and the ability of the Registrants’ counterparties to satisfy their financial commitments;

• Counterparties' collateral demands and other factors affecting the Registrants' liquidity position and financial condition;

• The Registrants’ ability to operate their businesses efficiently, manage capital expenditures and costs tightly, and generate earnings and cash flows from their asset-based businesses in relation to their debt and other obligations;

• The Registrants’ ability to enter into contracts to sell power and procure fuel on acceptable terms and prices;

• The liquidity and competitiveness of wholesale markets for energy commodities;

• Government regulation, including compliance with regulatory requirements and changes in market rules, rates, tariffs and environmental laws;

• Price mitigation strategies and other market structures employed by ISOs or RTOs;

• The Registrants’ ability to borrow additional funds and access capital markets, as well as GenOn’s substantial indebtedness and the possibility that the Registrants may incur additional indebtedness going forward;

• Operating and financial restrictions placed on the Registrants and their subsidiaries that are contained in the indentures governing GenOn’s outstanding notes, and in debt and other agreements of certain of the Registrants’ subsidiaries and project affiliates generally;

• The Registrants’ ability to implement their strategy of developing and building new power generation facilities;

• The Registrants’ ability to implement their strategy of finding ways to meet the challenges of climate change, clean air and protecting natural resources while taking advantage of business opportunities;

• The Registrants’ ability to implement their strategy of increasing the return on invested capital through operational performance improvements and a range of initiatives at plants and corporate offices to reduce costs or generate revenues;

• The Registrants’ ability to successfully evaluate investments in new business and growth initiatives;

• The Registrants’ ability to successfully integrate and manage any acquired businesses;

• The Registrants' ability to integrate the businesses and realize cost savings related to the NRG Merger; and

• The Registrants’ ability to develop and maintain successful partnering relationships.

Forward-looking statements speak only as of the date they were made, and the Registrants undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. The foregoing review of factors that could cause the Registrants’ actual results to differ materially from those contemplated in any forward-looking statements included in this Quarterly Report on Form 10-Q should not be construed as exhaustive.

2

GLOSSARY OF TERMS

When the following terms and abbreviations appear in the text of this report, they have the meanings indicated below:

2012 Form 10-K	The Registrants' Annual Report on Form 10-K for the year ended December 31, 2012
Ancillary Services	Services that ensure reliability and support the transmission of electricity from generation sites to customer loads. Such services include regulation service, reserves and voltage support
ASC	The FASB Accounting Standards Codification, which the FASB established as the source of authoritative U.S. GAAP
ASU	Accounting Standards Updates – updates to the ASC
Bankruptcy Court	United States, Bankruptcy Court for the Northern District of Texas, Fort Worth Division
CAA	Clean Air Act
CenterPoint	CenterPoint Energy, Inc. and its subsidiaries, on and after August 31, 2002, and Reliant Energy, Incorporated and its subsidiaries prior to August 31, 2002
Clean Water Act	Federal Water Pollution Control Act
Deactivation	Includes retirement, mothballing and long-term protective layup. In each instance, the deactivated unit cannot be currently called upon to generate electricity.
EPA	United States Environmental Protection Agency
Exchange Act	The Securities Exchange Act of 1934, as amended
FASB	Financial Accounting Standards Board
FERC	Federal Energy Regulatory Commission
GenOn	GenOn Energy, Inc. and, except where the context indicates otherwise, its subsidiaries
GenOn Americas Generation	GenOn Americas Generation, LLC and, except where the context indicates otherwise, its subsidiaries
GenOn Energy Holdings	GenOn Energy Holdings, Inc. and, except where the context indicates otherwise, its subsidiaries
GenOn Mid-Atlantic	GenOn Mid-Atlantic, LLC and, except where the context indicates otherwise, its subsidiaries, which include the coal generation units at two generating facilities under operating leases
ISO	Independent System Operator, also referred to as Regional Transmission Organization, or RTO
LIBOR	London Inter-Bank Offered Rate
Long-term protective layup	A descriptive term for GenOn's plans with respect to the Shawville coal-fired units, including retiring the units from service in accordance with the PJM tariff, maintenance of the units in accordance with the lease requirements and continued payment of the lease rent. Although the units are not decommissioned and reactivation remains a technical possibility, GenOn does not expect to make any further investment in environmental controls for the units. Further, reactivation after the long-term protective layup would likely involve numerous new permits and substantial additional investment.
MATS	Mercury and Air Toxics Standards promulgated by the EPA
MC Asset Recovery	MC Asset Recovery, LLC
MDE	Maryland Department of the Environment
Mirant	GenOn Energy Holdings, Inc. (formerly known as Mirant Corporation) and, except where the context indicates otherwise, its subsidiaries
Mirant/RRI Merger	The merger completed on December 3, 2010 pursuant to the Mirant/RRI Merger Agreement
Mirant/RRI Merger Agreement	The agreements by and among Mirant Corporation, RRI Energy, Inc. and RRI Energy Holdings, Inc. dated as of April 11, 2010
Mirant Debtors	GenOn Energy Holdings, Inc. (formerly known as Mirant Corporation) and certain of its subsidiaries
MISO	Midcontinent Independent System Operator, Inc.
MMBtu	Million British Thermal Units
MW	Megawatt
MWh	Saleable megawatt hours net of internal/parasitic load megawatt-hours
NAAQS	National Ambient Air Quality Standards

3

Net Exposure	Counterparty credit exposure to GenOn, GenOn Americas Generation or GenOn Mid-Atlantic, as applicable, net of collateral
NJDEP	New Jersey Department of Environmental Protection
NOL	Net Operating Loss
NOV	Notice of violation
NOx	Nitrogen oxide
NPDES	National pollutant discharge elimination system
NPNS	Normal Purchase Normal Sale
NRG	NRG Energy, Inc. and, except where the context indicates otherwise, its subsidiaries
NRG Americas	NRG Americas, Inc. (formerly known as GenOn Americas, Inc.)
NRG Marsh Landing	NRG Marsh Landing, LLC (formerly known as GenOn Marsh Landing, LLC)
NRG Merger	The merger completed on December 14, 2012 pursuant to the NRG Merger Agreement
NRG Merger Agreement	Agreement and Plan of Merger by and among NRG Energy, Inc., Plus Merger Corporation and GenOn Energy, Inc. dated as of July 20, 2012
NSR	New Source Review
OCI	Other comprehensive income
PADEP	Pennsylvania Department of Environmental Protection
PJM	PJM Interconnection, LLC
PJM market	The wholesale and retail electric market operated by PJM primarily in all or parts of Delaware, the District of Columbia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia
Plan	The plan of reorganization that was approved in conjunction with Mirant Corporation's emergence from bankruptcy protection on January 3, 2006
Registrants	GenOn, GenOn Americas Generation and GenOn Mid-Atlantic, collectively
Retirement	The unit has been removed from service and is unavailable for service and not expected to return to service in the future.
RGGI	Regional Greenhouse Gas Initiative
RMR	Reliability Must-Run
RTO	Regional Transmission Organization
Securities Act	The Securities Act of 1933, as amended
SO2	Sulfur dioxide
U.S.	United States of America
U.S. GAAP	Accounting principles generally accepted in the United States

4

PART I - FINANCIAL INFORMATION

ITEM 1 - CONDENSED CONSOLIDATED FINANCIAL STATEMENTS AND NOTES

GENON ENERGY, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Successor			Predecessor			Successor			Predecessor
	Three months ended			Three months ended			Six months ended			Six months ended
	June 30, 2013			June 30, 2012			June 30, 2013			June 30, 2012
	(In millions)			(In millions)			(In millions)			(In millions)
Operating Revenues
Operating revenues	$	716		$	521		$	1,140		$	1,242
Operating revenues — affiliate	9			—			15			—
Total operating revenues	725			521			1,155			1,242
Operating Costs and Expenses
Cost of operations	285			506			635			1,034
Cost of operations — affiliate	170			—			310			—
Depreciation and amortization	62			90			121			178
Selling, general and administrative	21			64			54			114
Selling, general and administrative — affiliate	19			—			36			—
Acquisition-related transaction and integration costs	22			—			41			—
Total operating costs and expenses	579			660			1,197			1,326
Operating Income/(Loss)	146			(139		)	(42		)	(84		)
Other Expense
Other income, net	—			—			2			2
Interest expense	(56		)	(85		)	(103		)	(174		)
Loss on debt extinguishment	(11		)	—			(11		)	—
Total other expense	(67		)	(85		)	(112		)	(172		)
Income/(Loss) Before Income Taxes	79			(224		)	(154		)	(256		)
Income tax (benefit)/expense	(6		)	4			(6		)	4
Net Income/(Loss)	$	85		$	(228	)	$	(148	)	$	(260	)

See accompanying notes to condensed consolidated financial statements.

5

GENON ENERGY, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS)

(Unaudited)

	Successor		Predecessor			Successor			Predecessor
	Three months ended		Three months ended			Six months ended			Six months ended
	June 30, 2013		June 30, 2012			June 30, 2013			June 30, 2012
	(In millions)		(In millions)			(In millions)			(In millions)
Net Income/(Loss)	$	85	$	(228	)	$	(148	)	$	(260	)
Other comprehensive loss net of reclassifications, net of tax of $0:
Unrealized gain/(loss) on derivatives	16		(16		)	17			(12		)
Defined benefit plans	29		1			30			2
Other, net	—		1			—			1
Other comprehensive income/(loss)	45		(14		)	47			(9		)
Comprehensive income/(loss)	$	130	$	(242	)	$	(101	)	$	(269	)

See accompanying notes to condensed consolidated financial statements.

6

GENON ENERGY, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

	June 30, 2013			December 31, 2012
	(unaudited)
	(In millions)
ASSETS
Current Assets
Cash and cash equivalents	$	248		$	825
Funds deposited by counterparties	134			140
Restricted cash	34			18
Accounts receivable — trade	186			138
Inventory	437			430
Derivative instruments	518			596
Derivative instruments — affiliate	5			8
Cash collateral paid in support of energy risk management activities	49			148
Prepayments and other current assets	181			215
Total current assets	1,792			2,518
Property, plant and equipment, net of accumulated depreciation of $129 and $9	3,953			3,919
Other Assets
Intangible assets, net of accumulated amortization of $18 and $1	67			68
Derivative instruments	342			511
Derivative instruments — affiliate	1			1
Deferred income taxes	197			209
Other non-current assets	190			235
Total other assets	797			1,024
Total Assets	$	6,542		$	7,461
LIABILITIES AND STOCKHOLDER'S EQUITY
Current Liabilities
Current portion of long-term debt and capital leases	$	41		$	32
Accounts payable	134			189
Accounts payable — affiliate	53			6
Derivative instruments	177			237
Derivative instruments — affiliate	11			8
Deferred income taxes	197			209
Cash collateral received in support of energy risk management activities	134			140
Accrued expenses and other current liabilities	266			338
Total current liabilities	1,013			1,159
Other Liabilities
Long-term debt and capital leases	3,623			4,170
Derivative instruments	70			123
Derivative instruments — affiliate	2			1
Out-of-market contracts	1,041			1,077
Other non-current liabilities	552			591
Total non-current liabilities	5,288			5,962
Total Liabilities	6,301			7,121
Commitments and Contingencies
Stockholder's Equity
Common stock: $0.001 par value, 1 share authorized and issued at June 30, 2013 and December 31, 2012	—			—
Additional paid-in capital	412			410
Accumulated deficit	(220		)	(72		)
Accumulated other comprehensive income	49			2
Total Stockholder's Equity	241			340
Total Liabilities and Stockholder's Equity	$	6,542		$	7,461

See accompanying notes to condensed consolidated financial statements.

7

GENON ENERGY, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Successor			Predecessor
	Six months ended			Six months ended
	June 30, 2013			June 30, 2012
	(In millions)			(In millions)
Cash Flows from Operating Activities
Net loss	$	(148	)	$	(260	)
Adjustments to reconcile net loss to net cash provided/(used) by operating activities:
Depreciation and amortization	121			178
Amortization of financing costs and debt discount/premiums	(43		)	8
Amortization of acquired and out-of-market contracts	(36		)	(22		)
Amortization of unearned equity compensation	7			9
Adjustment to loss on debt extinguishment	(28		)	—
Loss/(gain) on disposals and sales of assets	1			(8		)
Changes in derivative instruments	159			42
Excess materials and supplies inventory reserve	—			35
Lower of cost or market inventory adjustments	—			65
Advance settlement of out-of-market contract obligation	—			(20		)
Potomac River settlement reversal	—			(31		)
Large scale remediation and settlement costs	—			(3		)
Other, net	—			2
Changes in collateral deposits supporting energy risk management activities	99			9
Changes in other working capital	(22		)	(203		)
Net Cash Provided/(Used) by Operating Activities	110			(199		)
Cash Flows from Investing Activities
Capital expenditures	(190		)	(342		)
Proceeds from sale of assets, net	1			14
(Increase)/decrease in restricted cash, net	(16		)	167
Purchase of emission allowances, net of proceeds	(14		)	—
Net Cash Used by Investing Activities	(219		)	(161		)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	110			148
Payments for short and long-term debt	(578		)	(6		)
Net Cash (Used)/Provided by Financing Activities	(468		)	142
Net Decrease in Cash and Cash Equivalents	(577		)	(218		)
Cash and Cash Equivalents at Beginning of Period	825			1,539
Cash and Cash Equivalents at End of Period	$	248		$	1,321

See accompanying notes to condensed consolidated financial statements.

8

GENON AMERICAS GENERATION, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Successor			Predecessor			Successor			Predecessor
	Three months ended			Three months ended			Six months ended			Six months ended
	June 30, 2013			June 30, 2012			June 30, 2013			June 30, 2012
	(In millions)			(In millions)			(In millions)			(In millions)
Operating Revenues
Operating revenues	$	666		$	489		$	1,065		$	1,171
Operating revenues — affiliate	(28		)	65			105			35
Total operating revenues	638			554			1,170			1,206
Operating Costs and Expenses
Cost of operations	160			277			379			537
Cost of operations — affiliate	376			267			704			533
Depreciation and amortization	20			41			41			81
Selling, general and administrative	1			5			2			10
Selling, general and administrative — affiliate	22			23			42			39
Total operating costs and expenses	579			613			1,168			1,200
Operating Income/(Loss)	59			(59		)	2			6
Other Expense
Interest expense	(17		)	(18		)	(33		)	(36		)
Interest expense — affiliate	(1		)	(2		)	(3		)	(3		)
Total other expense	(18		)	(20		)	(36		)	(39		)
Income/(Loss) Before Income Taxes	41			(79		)	(34		)	(33		)
Income tax	—			—			—			—
Net Income/(Loss)	$	41		$	(79	)	$	(34	)	$	(33	)

See accompanying notes to condensed consolidated financial statements.

9

GENON AMERICAS GENERATION, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

	June 30, 2013		December 31, 2012
	(unaudited)
	(In millions)
ASSETS
Current Assets
Cash and cash equivalents	$	75	$	148
Accounts receivable — trade	160		125
Note receivable — affiliate	301		198
Inventory	222		226
Derivative instruments	517		596
Derivative instruments — affiliate	77		60
Cash collateral paid in support of energy risk management activities	37		91
Prepayments and other current assets	111		61
Total current assets	1,500		1,505
Property, plant and equipment, net of accumulated depreciation of $46 and $4	1,272		1,267
Other Assets
Intangible assets, net of accumulated amortization of $17 and $1	66		66
Derivative instruments	342		511
Derivative instruments — affiliate	16		25
Other non-current assets	47		13
Total other assets	471		615
Total Assets	$	3,243	$	3,387
LIABILITIES AND MEMBER'S EQUITY
Current Liabilities
Current portion of long-term debt and capital leases	$	5	$	5
Accounts payable	58		69
Accounts payable — affiliate	148		71
Derivative instruments	161		228
Derivative instruments — affiliate	126		134
Cash collateral received in support of energy risk management activities	134		140
Accrued expenses and other current liabilities	69		72
Total current liabilities	701		719
Other Liabilities
Long-term debt and capital leases	949		955
Derivative instruments	51		82
Derivative instruments — affiliate	39		51
Out-of-market contracts	542		554
Other non-current liabilities	101		103
Total non-current liabilities	1,682		1,745
Total Liabilities	2,383		2,464
Commitments and Contingencies
Member’s Equity
Member’s interest	860		923
Total Member’s Equity	860		923
Total Liabilities and Member’s Equity	$	3,243	$	3,387

See accompanying notes to condensed consolidated financial statements.

10

GENON AMERICAS GENERATION, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Successor			Predecessor
	Six months ended			Six months ended
	June 30, 2013			June 30, 2012
	(In millions)			(In millions)
Cash Flows from Operating Activities
Net loss	$	(34	)	$	(33	)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41			81
Amortization of debt premiums	(4		)	—
Amortization of out-of-market contracts	(12		)	—
Loss/(gain) on disposals and sales of assets	4			(1		)
Changes in derivative instruments	122			58
Excess materials and supplies inventory reserve	—			6
Lower of cost or market inventory adjustments	—			34
Potomac River settlement reversal	—			(31		)
Large scale remediation and settlement costs	—			(3		)
Changes in collateral deposits supporting energy risk management activities	48			230
Changes in other working capital	(51		)	(123		)
Net Cash Provided by Operating Activities	114			218
Cash Flows from Investing Activities
Capital expenditures	(35		)	(151		)
Decrease in restricted cash, net	—			166
(Increase)/decrease in note receivable — affiliate	(103		)	13
Purchase of emission allowances, net of proceeds	(14		)	—
Net Cash (Used)/Provided by Investing Activities	(152		)	28
Cash Flows from Financing Activities
Payments for short and long-term debt	(2		)	(2		)
Increase of note payable — affiliate	—			32
Capital contributions	37			—
Distributions to member	(70		)	(100		)
Net Cash Used by Financing Activities	(35		)	(70		)
Net (Decrease)/Increase in Cash and Cash Equivalents	(73		)	176
Cash and Cash Equivalents at Beginning of Period	148			267
Cash and Cash Equivalents at End of Period	$	75		$	443

See accompanying notes to condensed consolidated financial statements.

11

GENON MID-ATLANTIC, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Successor			Predecessor			Successor			Predecessor
	Three months ended			Three months ended			Six months ended			Six months ended
	June 30, 2013			June 30, 2012			June 30, 2013			June 30, 2012
	(In millions)			(In millions)			(In millions)			(In millions)
Operating Revenues
Operating revenues	$	46		$	8		$	6		$	135
Operating revenues — affiliate	197			200			335			393
Total operating revenues	243			208			341			528
Operating Costs and Expenses
Cost of operations	57			43			108			107
Cost of operations — affiliate	90			173			177			315
Depreciation and amortization	14			30			30			59
Selling, general and administrative — affiliate	17			18			33			30
Total operating costs and expenses	178			264			348			511
Operating Income/(Loss)	65			(56		)	(7		)	17
Other Expense
Interest expense	—			(1		)	—			(1		)
Interest expense — affiliate	(1		)	(1		)	(2		)	(2		)
Total other expense	(1		)	(2		)	(2		)	(3		)
Income/(Loss) Before Income Taxes	64			(58		)	(9		)	14
Income tax	—			—			—			—
Net Income/(Loss)	$	64		$	(58	)	$	(9	)	$	14

See accompanying notes to condensed consolidated financial statements.

12

GENON MID-ATLANTIC, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

	June 30, 2013		December 31, 2012
	(unaudited)
	(In millions)
ASSETS
Current Assets
Cash and cash equivalents	$	75	$	135
Accounts receivable — trade	2		4
Inventory	157		139
Derivative instruments	300		285
Derivative instruments — affiliate	78		109
Prepayments and other current assets	99		43
Total current assets	711		715
Property, plant and equipment, net of accumulated depreciation of $34 and $4	1,111		1,110
Other Assets
Intangible assets, net	1		1
Derivative instruments	210		351
Derivative instruments — affiliate	93		104
Other non-current assets	32		—
Total other assets	336		456
Total Assets	$	2,158	$	2,281
LIABILITIES AND MEMBER'S EQUITY
Current Liabilities
Current portion of long-term debt and capital leases	$	7	$	5
Accounts payable	18		16
Accounts payable — affiliate	—		2
Derivative instruments	5		3
Derivative instruments — affiliate	68		97
Cash collateral received in support of energy risk management activities	75		57
Accrued taxes and other current liabilities	34		38
Total current liabilities	207		218
Other Liabilities
Long-term debt and capital leases	7		9
Derivative instruments — affiliate	35		55
Out-of-market contracts	542		554
Other non-current liabilities	55		56
Total non-current liabilities	639		674
Total Liabilities	846		892
Commitments and Contingencies
Member’s Equity
Member’s interest	1,312		1,389
Total Member’s Equity	1,312		1,389
Total Liabilities and Member’s Equity	$	2,158	$	2,281

See accompanying notes to condensed consolidated financial statements.

13

GENON MID-ATLANTIC, LLC AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Successor			Predecessor
	Six months ended			Six months ended
	June 30, 2013			June 30, 2012
	(In millions)			(In millions)
Cash Flows from Operating Activities
Net (loss)/income	$	(9	)	$	14
Adjustments to reconcile net (loss)/income to net cash provided by operating activities:
Depreciation and amortization	30			59
Amortization of out-of-market contracts	(12		)	—
Loss/(gain) on disposals and sales of assets	4			(1		)
Changes in derivative instruments	121			71
Excess materials and supplies inventory reserve	—			4
Lower of cost or market inventory adjustments	—			34
Potomac River settlement reversal	—			(31		)
Large scale remediation and settlement costs	—			(3		)
Changes in collateral deposits supporting energy risk management activities	18			168
Changes in other working capital	(112		)	(113		)
Net Cash Provided by Operating Activities	40			202
Cash Flows from Investing Activities
Capital expenditures	(30		)	(134		)
Decrease in restricted cash, net	—			166
Net Cash (Used)/Provided by Investing Activities	(30		)	32
Cash Flows from Financing Activities
Payments for short and long-term debt	(2		)	(2		)
Issuance of notes payable — affiliate	2			—
Distributions to member	(70		)	(100		)
Net Cash Used by Financing Activities	(70		)	(102		)
Net (Decrease)/Increase in Cash and Cash Equivalents	(60		)	132
Cash and Cash Equivalents at Beginning of Period	135			68
Cash and Cash Equivalents at End of Period	$	75		$	200

See accompanying notes to condensed consolidated financial statements.

14

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

Note 1 — Basis of Presentation (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn Energy, Inc., a wholly-owned subsidiary of NRG, is a wholesale power generator engaged in the ownership and operation of power generation facilities, with approximately 21,205 MW of net electric generating capacity located in the U.S.

GenOn Americas Generation is a wholesale power generator with approximately 7,852 MW of net electric generating capacity located, in many cases, near major metropolitan areas. GenOn Americas Generation's electric generating capacity is part of the 21,205 MW of net electric generating capacity of GenOn.

GenOn Mid-Atlantic operates and owns or leases 4,683 MW of net electric generating capacity in the Washington, D.C. and Baltimore areas. GenOn Mid-Atlantic’s electric generating capacity is part of the 7,852 MW of net electric generating capacity of GenOn Americas Generation. GenOn Mid-Atlantic’s generating facilities serve the Eastern PJM markets.

GenOn Americas Generation and GenOn Mid-Atlantic are Delaware limited liability companies and indirect wholly-owned subsidiaries of GenOn. GenOn Mid-Atlantic is a wholly-owned subsidiary of NRG North America and an indirect wholly-owned subsidiary of GenOn Americas Generation.

The Registrants sell power from their generation portfolio, offer capacity or similar products to retail electric providers and others, and provide Ancillary Services to support system reliability.

This is a combined quarterly report of the Registrants for the quarter ended June 30, 2013. The notes to the condensed consolidated financial statements apply to the Registrants as indicated parenthetically next to each corresponding disclosure. The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with the SEC's regulations for interim financial information and with the instructions to Form 10-Q. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The following notes should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the Registrants' financial statements set forth in the 2012 Form 10-K. Interim results are not necessarily indicative of results for a full year.

In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Registrants' consolidated financial positions as of June 30, 2013, and the results of operations, comprehensive loss and cash flows for the three months ended June 30, 2013, and 2012.

NRG Merger, Predecessor and Successor Reporting

On December 14, 2012, NRG completed the acquisition of GenOn with GenOn continuing as a wholly-owned subsidiary of NRG. The NRG Merger is accounted for under the acquisition method of accounting. Fair value adjustments related to the NRG Merger have been pushed down to GenOn, GenOn Americas Generation and GenOn Mid-Atlantic, resulting in certain assets and liabilities of the Registrants being recorded at fair value at December 15, 2012. See Note 3, NRG Merger, for further discussion.

The Registrants’ consolidated statements of operations subsequent to the NRG Merger include amortization expense relating to fair value adjustments and depreciation expense based on the fair value of the Registrants’ property, plant and equipment. In addition, effective with the NRG Merger, the Registrants adopted accounting policies of NRG. Therefore, the Registrants' financial information prior to the NRG Merger is not comparable to its financial information subsequent to the NRG Merger.

As a result of the impact of pushdown accounting, the financial statements and certain note presentations separate the Registrants' presentations into two distinct periods, the period before the consummation of the NRG Merger (labeled predecessor) and the period after that date (labeled successor), to indicate the application of different basis of accounting between the periods presented.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.

Reclassifications

Certain prior-year amounts have been reclassified for comparative purposes. The reclassifications did not affect results from operations or cash flows.

15

Note 2 — Summary of Significant Accounting Policies (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Recent Accounting Developments

ASU 2011-11 —Effective January 1, 2013, the Registrants adopted the provisions of ASU No. 2011-11, Balance Sheet (Topic 210) Disclosures about Offsetting Assets and Liabilities, or ASU No. 2011-11, and began providing enhanced disclosures regarding the effect or potential effect of netting arrangements on an entity's financial position by improving information about financial instruments and derivative instruments that either (1) offset in accordance with either ASC 210-20-45 or ASC 810-20-45 or (2) are subject to an enforceable master netting arrangement or similar agreement, irrespective of whether they are offset. Reporting entities are required to disclose both gross and net information about both instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. The disclosures required by ASU No. 2011-11 are required to be adopted retroactively. As this guidance provides only disclosure requirements, the adoption of this standard will not impact the Registrants' results of operations, cash flows or financial position.

ASU 2013-02 (GenOn) - Effective January 1, 2013, GenOn adopted the provisions of ASU No. 2013-02, Other Comprehensive Income (Topic 220) Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, or ASU No. 2013-02, and began reporting the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in net income within the notes to the financial statements if the amount being reclassified is required under U.S. GAAP to be reclassified in its entirety to net income in the same reporting period. For other amounts not required by U.S. GAAP to be reclassified in their entirety to net income in the same reporting period, an entity is required to cross-reference other disclosures which provide additional information about the amounts. The provisions of ASU No. 2013-02 are required to be adopted prospectively. As this guidance provides only presentation requirements, the adoption of this standard did not impact GenOn's results of operations, cash flows or financial position.

Note 3 — NRG Merger (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

On December 14, 2012, NRG completed the acquisition of GenOn.  Consideration for the acquisition was valued at $2.2 billion and was comprised of 0.1216 shares of NRG common stock for each outstanding share of GenOn, including restricted stock units outstanding, on the acquisition date, except for fractional shares which were paid in cash. 

The acquisition was recorded as a business combination, with identifiable assets acquired and liabilities assumed provisionally recorded at their estimated fair values on the acquisition date. The initial accounting for the business combination is not complete because the evaluations necessary to assess the fair value of certain net assets acquired is still in process. See Note 3, NRG Merger, in the Registrants' 2012 Form 10-K for additional information related to the NRG Merger.

The following tables summarize the historical carrying amounts, the acquisition accounting adjustments, the preliminary acquisition-date fair value and the measurement period adjustments through June 30, 2013 to the provisional allocation for assets acquired and liabilities assumed initially recorded in 2012 due to the ongoing evaluation of initial estimates. The allocation of the purchase price may be modified up to one year from the date of acquisition as more information is obtained about the fair value of assets acquired and liabilities assumed.

GenOn

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	983	$	—		$	983	$	—		$	983
Other current and non-current assets	2,049		(664		)	1,385		(18		)	1,367
Property, plant and equipment	6,286		(2,350		)	3,936		(27		)	3,909
Derivative assets	1,143		14			1,157		—			1,157
Deferred income taxes	220		—			220		—			220
Total assets	$	10,681	$	(3,000	)	$	7,681	$	(45	)	$	7,636
Liabilities
Other current and non-current liabilities	$	1,299	$	13		1,312		$	10		$	1,322
Out-of-market contracts and leases	331		733			1,064		15			1,079
Derivative liabilities	414		(15		)	399		—			399
Deferred income taxes	220		—			220		—			220
Long-term debt and capital leases	3,725		478			4,203		3			4,206
Total liabilities	$	5,989	$	1,209		$	7,198	$	28		$	7,226
Net assets	$	4,692	$	(4,209	)	$	483	$	(73	)	$	410

16

GenOn Americas Generation

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	171	$	—		$	171	$	—		$	171
Other current and non-current assets	1,509		(531		)	978		(14		)	964
Property, plant and equipment	2,875		(1,546		)	1,329		(60		)	1,269
Derivative assets	1,226		12			1,238		—			1,238
Total assets	$	5,781	$	(2,065	)	$	3,716	$	(74	)	$	3,642
Liabilities
Other current and non-current liabilities	$	705	$	(34	)	$	671	$	—		$	671
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	539		(10		)	529		—			529
Long-term debt and capital leases	862		99			961		—			961
Total liabilities	$	2,106	$	595		$	2,701	$	15		$	2,716
Net assets	$	3,675	$	(2,660	)	$	1,015	$	(89	)	$	926

GenOn Mid-Atlantic

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	163	$	—		$	163	$	—		$	163
Other current and non-current assets	700		(502		)	198		(12		)	186
Property, plant and equipment	2,399		(1,178		)	1,221		(110		)	1,111
Derivative assets	851		12			863		—			863
Total assets	$	4,113	$	(1,668	)	$	2,445	$	(122	)	$	2,323
Liabilities
Other current and non-current liabilities	$	198	$	6		$	204	—			$	204
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	172		(10		)	162		—			162
Long-term debt and capital leases	14		—			14		—			14
Total liabilities	$	384	$	536		$	920	$	15		$	935
Net assets	$	3,729	$	(2,204	)	$	1,525	$	(137	)	$	1,388

The estimated fair values of the property, plant and equipment were significantly lower than the book value, which reflects changes to expected market dynamics, including commodity prices, resulting in lower estimated cash flows and in some cases, shorter useful lives of the underlying assets. The measurement period adjustments for property, plant and equipment primarily reflect revisions of various estimates based on additional information available. In addition, the difference between the historical tax basis of the assets and liabilities over the net amount assigned to the assets and liabilities in acquisition accounting was recorded as a net deferred tax asset. Based on cumulative pre-tax losses, a valuation allowance for the full amount of the net deferred tax assets was also recorded.

17

Note 4 — Fair Value of Financial Instruments (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

This footnote should be read in conjunction with the complete description under Note 5, Fair Value of Financial Instruments, to the Registrants' 2012 Form 10-K.

For cash and cash equivalents, funds deposited by counterparties (GenOn), accounts receivable, note receivable — affiliate (GenOn Americas Generation), accounts payable, accrued expenses and other current liabilities, restricted cash, and cash collateral paid and received in support of energy risk management activities, the carrying amount approximates fair value because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy.

The estimated carrying amounts and fair values of GenOn and GenOn Americas Generation’s long-term debt, including current portion, are as follows:

GenOn

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	3,649	$	3,545	$	4,185	$	4,195

GenOn Americas Generation

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	942	$	909	$	946	$	953

The fair value of GenOn and GenOn Americas Generation's publicly-traded long-term debt is based on quoted market prices and is classified as Level 1 within the fair value hierarchy. The fair value of GenOn's non publicly-traded long-term debt is estimated using current interest rates for similar instruments with equivalent credit quality and is classified as Level 3 within the fair value hierarchy.

Recurring Fair Value Measurements

Derivative assets and liabilities and trust fund investments are carried at fair market value. Realized and unrealized gains and losses included in earnings that are related to energy derivatives are recorded in operating revenues and cost of operations.

GenOn

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn’s consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	127	$	722	$	17	$	866
Derivative liabilities:
Commodity contracts	$	44	$	169	$	14	$	227
Interest rate contracts	—		33		—		33
Total liabilities	$	44	$	202	$	14	$	260
Other assets (a)	$	44	$	—	$	—	$	44

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

18

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	139	$	946	$	31	$	1,116
Derivative liabilities:
Commodity contracts	$	52	$	253	$	14	$	319
Interest rate contracts	—		50		—		50
Total liabilities	$	52	$	303	$	14	$	369
Other assets (a)	$	43	$	—	$	—	$	43

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30,2013 and 2012. The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for derivatives that are recognized at fair value in GenOn’s consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(36	)	$	17		$	(31	)
Total gains/(losses) included in earnings — realized/unrealized	3			(95		)	(16		)	(100		)
Purchases	6			—			2			—
Ending balance	$	3		$	(131	)	$	3		$	(131	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(131	)	$	1		$	(136	)

(a) Consists of derivative assets and liabilities, net.

GenOn Americas Generation

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Americas Generation's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	149	$	784	$	19	$	952
Derivative liabilities:
Commodity contracts	$	103	$	258	$	16	$	377

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	170	$	991	$	31	$	1,192
Derivative liabilities:
Commodity contracts	$	123	$	358	$	14	$	495

19

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30, 2013 and 2012. The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for GenOn Americas Generation's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(30	)	$	17		$	(32	)
Total gains/(losses) included in earnings — realized/unrealized	3			(83		)	(16		)	(81		)
Purchases	6			—			2			—
Ending balance	$	3		$	(113	)	$	3		$	(113	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(121	)	$	1		$	(120	)

(a)    Consists of derivative assets and liabilities, net.

GenOn Mid-Atlantic

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Mid-Atlantic's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	68	$	609	$	4	$	681
Derivative liabilities:
Commodity contracts	$	20	$	86	$	2	$	108

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	63	$	778	$	8	$	849
Derivative liabilities:
Commodity contracts	$	16	$	138	$	1	$	155

20

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30,2013 and 2012. The following tables reconcile, for the three and six months endedJune 30, 2013 and 2012, the beginning and ending balances for GenOn Mid-Atlantic's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(88	)	$	7		$	(64	)
Total gains/(losses) included in earnings — realized/unrealized	2			(50		)	(7		)	(74		)
Purchases	6			—			2			—
Ending balance	$	2		$	(138	)	$	2		$	(138	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	8		$	(90	)	$	1		$	(115	)

(a) Consists of derivative assets and liabilities, net.

Derivative Fair Value Measurements

A portion of the Registrants' contracts are exchange-traded contracts with readily available quoted market prices. A majority of the Registrants' contracts are non-exchange-traded contracts valued using prices provided by external sources, primarily price quotations available through brokers or over-the-counter and on-line exchanges. For the majority of the Registrants' markets, the Registrants receive quotes from multiple sources. To the extent that the Registrants receive multiple quotes, the Registrants' prices reflect the average of the bid-ask mid-point prices obtained from all sources that the Registrants believe provide the most liquid market for the commodity. If the Registrants receive one quote, then the mid-point of the bid-ask spread for that quote is used. The terms for which such price information is available vary by commodity, region and product. A significant portion of the fair value of the Registrants' derivative portfolio is based on price quotes from brokers in active markets who regularly facilitate those transactions and the Registrants believe such price quotes are executable. The Registrants do not use third party sources that derive price based on proprietary models or market surveys. The remainder of the assets and liabilities represents contracts for which external sources or observable market quotes are not available for the whole term or for certain delivery months. These contracts are valued using various valuation techniques including but not limited to internal models that apply fundamental analysis of the market and corroboration with similar markets. As of June 30, 2013, contracts valued with prices provided by models and other valuation techniques make up 2% of GenOn's derivative assets and 5% of GenOn's derivative liabilities, 2% of GenOn Americas Generation’s derivative assets and 4% of GenOn Americas Generation's derivative liabilities and 1% of GenOn Mid-Atlantic’s derivative assets and 2% of GenOn Mid-Atlantic's derivative liabilities.

The fair value of each contract is discounted using a risk free interest rate. In addition, the Registrants apply a credit reserve to reflect credit risk which is calculated based on published default probabilities. To the extent that the Registrants’ net exposure under a specific master agreement is an asset, the Registrants use the counterparty's default swap rate. If the net exposure under a specific master agreement is a liability, the Registrants use their default swap rate. The credit reserve is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume the Registrants’ liabilities or that a market participant would be willing to pay for the Registrants’ assets. The Registrants' credit reserves were as follows:

	As of June 30, 2013			As of December 31, 2012
	(In millions)
GenOn	$	(3	)	$	(4	)
GenOn Americas Generation	$	(3	)	$	(4	)
GenOn Mid-Atlantic	$	(5	)	$	(4	)

21

Concentration of Credit Risk

In addition to the credit risk discussion as disclosed in Note 2, Summary of Significant Accounting Policies, to the Registrants' 2012 Form 10-K, the following is a discussion of the concentration of credit risk for the Registrants’ financial instruments. Credit risk relates to the risk of loss resulting from non-performance or non-payment by counterparties pursuant to the terms of their contractual obligations. The Registrants are exposed to counterparty credit risk through various activities including wholesale sales and fuel purchases.

Counterparty Credit Risk

The Registrants monitor and manage counterparty credit risk through credit policies that include: (i) an established credit approval process; (ii) daily monitoring of counterparties' credit limits; (iii) the use of credit mitigation measures such as margin, collateral, prepayment arrangements, or volumetric limits; (iv) the use of payment netting arrangements; and (v) the use of master netting agreements that allow for the netting of positive and negative exposures of various contracts associated with a single counterparty. Risk surrounding counterparty performance and credit could ultimately impact the amount and timing of expected cash flows. The Registrants seek to mitigate counterparty credit risk with a diversified portfolio of counterparties. The Registrants also have credit protection within various agreements to call on additional collateral support if and when necessary. Cash margin is collected and held to cover the credit risk of the counterparty until positions settle.

As of June 30, 2013, GenOn's counterparty credit exposure was $810 million and GenOn held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $735 million. Approximately 88% of GenOn's exposure before collateral is expected to roll off by the end of 2014. As of June 30, 2013, GenOn Americas Generation’s counterparty credit exposure was $803 million and GenOn Americas Generation held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $728 million. Approximately 88% of GenOn Americas Generation’s exposure before collateral is expected to roll off by the end of 2014. As of June 30, 2013, GenOn Mid-Atlantic’s counterparty credit exposure was $512 million and GenOn Mid-Atlantic held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $437 million. Approximately 89% of GenOn Mid-Atlantic’s exposure before collateral is expected to roll off by the end of 2014. Counterparty credit exposure is valued through observable market quotes and discounted at a risk free interest rate. The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for the Registrants with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market, NPNS and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables.

GenOn

Category	Net Exposure (a) (% of Total)
Financial institutions	60	%
Utilities, energy merchants, marketers and other	20	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a) Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $495 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

22

GenOn Americas Generation

Category	Net Exposure (a) (% of Total)
Financial institutions	61	%
Utilities, energy merchants, marketers and other	19	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a)    Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Americas Generation has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $494 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn Americas Generation does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

GenOn Mid-Atlantic

Category	Net Exposure (a) (% of Total)
Financial institutions	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	100	%

(a)Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Mid-Atlantic has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $407 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn Mid-Atlantic does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

23

Note 5 — Accounting for Derivative Instruments and Hedging Activities (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

This footnote should be read in conjunction with the complete description under Note 6, Accounting for Derivative Instruments and Hedging Activities, to the Registrants' 2012 Form 10-K.

Energy-Related Commodities(GenOn)

As of June 30, 2013, GenOn had energy-related derivative financial instruments extending through 2017.

Interest Rate Swaps (GenOn)

In 2010, NRG Marsh Landing entered into interest rate protection agreements (interest rate swaps) in connection with its project financing, which have been designated as cash flow hedges. NRG Marsh Landing entered into the interest rate swaps to reduce the risks with respect to the variability of the interest rates for the term loans. As of June 30, 2013, the maximum length of time GenOn is hedging its exposure to the variability in future cash flows that may result from changes in interest rates is 10 years.

Volumetric Underlying Derivative Transactions (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The following table summarizes the net notional volume buy/(sell) of the Registrants’ open derivative transactions broken out by commodity, excluding those derivatives that qualified for the NPNS exception as of June 30, 2013 and December 31, 2012. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date.

		GenOn				GenOn Americas Generation				GenOn Mid-Atlantic
		Total Volume				Total Volume				Total Volume
		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012
Commodity	Units	(In millions)
Coal	Short Ton	7		5		4		4		4		4
Natural Gas	MMBtu	(163)		(194)		(121)		(150)		(121)		(150)
Power	MWh	(33)		(43)		(19)		(22)		(19)		(22)
Interest	Dollars	$	500	$	475	$	—	$	—	$	—	$	—

Fair Value of Derivative Instruments (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The following tables summarize the fair value within the derivative instrument valuation on the balance sheet:

GenOn

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Designated as Cash Flow Hedges:
Interest rate contracts current	$	—	$	—	$	14	$	9
Interest rate contracts long-term	—		—		19		41
Total Derivatives Designated as Cash Flow Hedges	—		—		33		50
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	523		604		174		236
Commodity contracts long-term	343		512		53		83
Total Derivatives Not Designated as Cash Flow Hedges	866		1,116		227		319
Total Derivatives	$	866	$	1,116	$	260	$	369

24

GenOn Americas Generation

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	594	$	656	$	287	$	362
Commodity contracts long-term	358		536		90		133
Total Derivatives Not Designated as Cash Flow Hedges	$	952	$	1,192	$	377	$	495

GenOn Mid-Atlantic

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	378	$	394	$	73	$	100
Commodity contracts long-term	303		455		35		55
Total Derivatives Not Designated as Cash Flow Hedges	$	681	$	849	$	108	$	155

The Registrants have elected to present derivative assets and liabilities on the balance sheet on a trade-by-trade basis and do not offset amounts at the counterparty master agreement level. In addition, collateral received or paid on the Registrants' derivative assets or liabilities are recorded on a separate line item on the balance sheet. The following tables summarize the offsetting of derivatives by counterparty master agreement level and collateral received or paid:

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	860		$	(191	)	$	(219	)	$	450
Derivative assets - affiliate	6			(6		)	—			—
Derivative liabilities	(214		)	191			—			(23		)
Derivative liabilities - affiliate	(13		)	6			—			(7		)
Total commodity contracts	639			—			(219		)	420
Interest rate contracts:
Derivative liabilities	(33		)	—			—			(33		)
Total interest rate contracts	(33		)	—			—			(33		)
Total derivative instruments	$	606		$	—		$	(219	)	$	387

25

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	859		$	(191	)	$	(219	)	$	449
Derivative assets - affiliate	93			(93		)	—			—
Derivative liabilities	(212		)	191			—			(21		)
Derivative liabilities - affiliate	(165		)	93			—			(72		)
Total derivative instruments	$	575		$	—		$	(219	)	$	356

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	510		$	(5	)	$	(75	)	$	430
Derivative assets - affiliate	171			(103		)	—			68
Derivative liabilities	(5		)	5			—			—
Derivative liabilities - affiliate	(103		)	103			—			—
Total derivative instruments	$	573		$	—		$	(75	)	$	498

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	9			(9		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(9		)	9			—			—
Total commodity contracts	797			—			(242		)	555
Interest rate contracts:
Derivative liabilities	(50		)	—			—			(50		)
Total derivative instruments	$	747		$	—		$	(242	)	$	505

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	85			(85		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(185		)	85			—			(100		)
Total derivative instruments	$	697		$	—		$	(242	)	$	455

26

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	636		$	(3	)	$	(57	)	$	576
Derivative assets - affiliate	213			(152		)	—			61
Derivative liabilities	(3		)	3			—			—
Derivative liabilities - affiliate	(152		)	152			—			—
Total derivative instruments	$	694		$	—		$	(57	)	$	637

Accumulated Other Comprehensive Loss (GenOn)

The following table summarizes the effects on GenOn's accumulated OCI balance attributable to cash flow hedge derivatives:

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Accumulated OCI balance, beginning of period	$	2		$	(30	)	$	1		$	(34	)
Recognized in OCI on interest rate derivatives	17			(15		)	19			(11		)
Reclassified from accumulated OCI into earnings(a)(b)	(1		)	(1		)	(2		)	(1		)
Accumulated OCI balance, end of period	$	18		$	(46	)	$	18		$	(46	)

(a) Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded in interest expense.

(b) All of the forecasted transactions (future interest payments) were deemed probable of occurring; therefore, no cash flow hedges were discontinued and no amount was recognized in GenOn’s results of operations as a result of discontinued cash flow hedges.

Because a significant portion of the interest expense incurred by NRG Marsh Landing during construction was capitalized, amounts included in accumulated other comprehensive loss associated with construction period interest payments will be reclassified into earnings over the expected useful life of the Marsh Landing generating facility, which commenced commercial operations on May 1, 2013.

27

Impact of Derivative Instruments on the Statements of Operations (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow hedges are reflected in current period earnings.

The following tables summarize the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Registrants’ statements of operations. These amounts are included within operating revenues and cost of operations.

GenOn

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(99	)	$	(99	)	$	(197	)	$	(228	)
Net unrealized gains/(losses) on open positions related to economic hedges	161			(54		)	38			182
Total unrealized mark-to-market gains/(losses) for economic hedging activities	62			(153		)	(159		)	(46		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	63		$	(142	)	$	(159	)	$	(42	)

	Successor		Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	45	$	(102	)	$	(190	)	$	41
Cost of operations	18		(40		)	31			(83		)
Total impact to statements of operations	$	63	$	(142	)	$	(159	)	$	(42	)

28

GenOn Americas Generation

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(75	)	$	(73	)	$	(149	)	$	(173	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(46		)	26			110
Total unrealized mark-to-market gains/(losses) for economic hedging activities	11			(119		)	(123		)	(63		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	12		$	(108	)	$	(123	)	$	(59	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(2	)	$	(68	)	$	(153	)	$	7
Cost of operations	14			(40		)	30			(66		)
Total impact to statements of operations	$	12		$	(108	)	$	(123	)	$	(59	)

GenOn Mid-Atlantic

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(76	)	$	(73	)	$	(150	)	$	(175	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(40		)	28			104
Total unrealized gains/(losses)	$	10		$	(113	)	$	(122	)	$	(71	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(4	)	$	(66	)	$	(152	)	$	1
Cost of operations	14			(47		)	30			(72		)
Total impact to statements of operations	$	10		$	(113	)	$	(122	)	$	(71	)

Credit Risk Related Contingent Features (GenOn and GenOn Americas Generation)

Certain of GenOn and GenOn Americas Generation’s hedging agreements contain provisions that require the Registrants to post additional collateral if the counterparty determines that there has been deterioration in credit quality, generally termed "adequate assurance" under the agreements, or require the Registrants to post additional collateral if there were a one notch downgrade in the Registrants’ credit rating. The collateral required for contracts that have adequate assurance clauses that are in net liability positions as of June 30, 2013 was $15 million for GenOn and GenOn Americas Generation. The collateral required for contracts with credit rating contingent features that are in a net liability position as of June 30, 2013, was $1 million for GenOn and GenOn Americas Generation. In addition, GenOn and GenOn Americas Generation are parties to certain marginable agreements under which they have net liability positions, but the counterparties have not called for collateral due, which is approximately $4 million for GenOn and GenOn Americas Generation as of June 30, 2013. At June 30, 2013, GenOn Mid-Atlantic did not have any financial instruments with credit risk related contingent features.

See Note 4, Fair Value of Financial Instruments, for discussion regarding concentration of credit risk.

29

Note 6 — Debt (GenOn)

Redemption of Senior Unsecured Notes, Due 2014, or 2014 Senior Notes

In June 2013, GenOn redeemed all of the 2014 Senior Notes, with an aggregate outstanding principal amount of $575 million, at a redemption percentage of 106.778% of face value, as well, as any accrued and unpaid interest as of the redemption date. In connection with the redemption, an $11 million loss on the debt extinguishment of the 2014 Senior Notes was recorded during the three months ended June 30, 2013 which primarily consisted of a make whole premium payment offset by the write-off of unamortized premium.

NRG Marsh Landing Credit Agreement Term Conversion

In May 2013, NRG Marsh Landing met the conditions under the credit agreement to convert the construction loan for the facility to a term loan which will amortize on a predetermined basis. Prior to term conversion, NRG Marsh Landing drew the remaining funds available under the facility in order to pay costs due for construction. NRG Marsh Landing also issued a $26 million letter of credit under the facility in support of its debt service requirements. Concurrently with the term conversion, the $80 million cash collateralized letter of credit issued by GenOn Energy Holdings on behalf of NRG Marsh Landing in support of its collateral requirements under the PPA with PG&E was returned and the related letter of credit facility was terminated.

Note 7 — Segment Reporting (GenOn and GenOn Americas Generation)

Prior to the NRG Merger, GenOn had the following segments: Eastern PJM, Western PJM/MISO, California, Energy Marketing and Other Operations. GenOn Americas Generation previously had the following segments: Eastern PJM, Northeast, California, Energy Marketing and Other Operations. In the fourth quarter of 2012, in conjunction with the NRG Merger, GenOn and GenOn Americas Generation began reporting the following segments: East, South Central, West and Corporate. All GenOn Mid-Atlantic entities are included within the GenOn East segment. There are distinct components with separate operating results and management structures for each segment, which are based on the geographical location of the power generation operations. GenOn and GenOn Americas Generation have recast the data from prior periods to reflect this change in reportable segments to conform to the current year presentation.

GenOn

Successor	Three months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	617		$	—		$	96	$	3		$	716
Operating revenues—affiliate	(4		)	13			—		—			9
Depreciation and amortization	47			2			9		4			62
Income/(loss) before income taxes	126			(2		)	37		(82		)	79
Net income/(loss)	$	126		$	(2	)	$	37	$	(76	)	$	85
Total assets	$	4,379		$	216		$	1,036	$	911		$	6,542

Predecessor	Three months ended June 30, 2012
	East			South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	455		$	8	$	58		$	—		$	521
Depreciation and amortization	71			2		12			5			90
(Loss)/income before income taxes	(115		)	3		(20		)	(92		)	(224		)
Net (loss)/income	$	(115	)	$	3	$	(20	)	$	(96	)	$	(228	)

30

Successor	Six months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	996		$	—		$	136	$	8		$	1,140
Operating revenues—affiliate	(4		)	19			—		—			15
Depreciation and amortization	91			3			20		7			121
(Loss)/income before income taxes	(9		)	(8		)	17		(154		)	(154		)
Net (loss)/income	$	(9	)	$	(8	)	$	17	$	(148	)	$	(148	)

Predecessor	Six months ended June 30, 2012
	East			South Central			West			Corporate			Total
	(In millions)
Operating revenues	$	1,141		$	8		$	93		$	—		$	1,242
Depreciation and amortization	140			5			23			10			178
Loss before income taxes	(39		)	(1		)	(29		)	(187		)	(256		)
Net loss	$	(39	)	$	(1	)	$	(29	)	$	(191	)	$	(260	)

GenOn Americas Generation

Successor	Three months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	598	$	—	$	68		$	—		$	666
Operating revenues—affiliate	1		14		(43		)	—			(28		)
Depreciation and amortization	19		—		1			—			20
Income/(loss) before income taxes	62		—		—			(21		)	41
Net income/(loss)	$	62	$	—	$	—		$	(21	)	$	41
Total assets	$	2,579	$	—	$	175		$	489		$	3,243

Predecessor	Three months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	427		$	6	$	56	$	—		$	489
Operating revenues—affiliate	54			6		5		—			65
Depreciation and amortization	36			—		3		2			41
(Loss)/income before income taxes	(67		)	5		5		(22		)	(79		)
Net (loss)/income	$	(67	)	$	5	$	5	$	(22	)	$	(79	)

Successor	Six months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	974	$	—	$	91		$	—		$	1,065
Operating revenues—affiliate	134		14		(43		)	—			105
Depreciation and amortization	38		—		3			—			41
Income/(loss) before income taxes	2		—		8			(44		)	(34		)
Net income/(loss)	$	2	$	—	$	8		$	(44	)	$	(34	)

Predecessor	Six months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	1,078		$	6	$	87	$	—		$	1,171
Operating revenues—affiliate	25			6		4		—			35
Depreciation and amortization	71			—		7		3			81
(Loss)/income before income taxes	(1		)	5		5		(42		)	(33		)
Net (loss)/income	$	(1	)	$	5	$	5	$	(42	)	$	(33	)

31

Note 8 —  Income Taxes (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn

GenOn’s income tax (benefit)/expense consisted of the following:

	Successor		Predecessor		Successor		Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Income/(loss) before income taxes	79		(224	)	(154	)	(256	)
Income tax (benefit)/expense	(6	)	4		(6	)	4
Effective tax rate	(7.59	)%	(1.79	)%	3.90	%	(1.56	)%

GenOn

For the three and six months ended June 30,2013 and 2012, GenOn's overall effective tax rate was different than the statutory rate of 35% primarily due to the recording of a valuation allowance against NOLs generated during the period.

Tax allocation — NRG will allocate taxes to GenOn Americas Generation and GenOn Mid-Atlantic, subsidiaries of GenOn using the pro rata method of income tax allocation as prescribed in ASC 740, Income Taxes. Electing to use the pro rata method requires presentation of a pro forma income statement for the most recent year and interim period reflecting a tax provision calculated on a separate return basis. Due to historical losses and the uncertainty surrounding the ability to generate future earnings, GenOn has recorded a full valuation allowance against its net deferred tax assets. Any change in the valuation allowance will be offset to the corresponding income tax expense or benefit. For the three and six months ended June 30, 2013 and 2012, GenOn recorded an income tax benefit and expense which relate to FIN 48 reserves for uncertain tax benefits.

GenOn Americas Generation

GenOn Americas Generation and most of its subsidiaries are limited liability companies that are treated as branches of NRG Americas for income tax purposes. As a result, NRG Americas, GenOn and NRG have direct liability for the majority of the federal and state income taxes relating to GenOn Americas Generation's operations. Several of GenOn Americas Generation's subsidiaries exist as regarded corporate entities for income tax purposes. For the subsidiaries that continue to exist as corporate regarded entities, GenOn Americas Generation allocates current and deferred income taxes to each corporate regarded entity as if such entity were a single taxpayer utilizing the asset and liability method to account for income taxes. To the extent GenOn Americas Generation provides tax expense or benefit, any related tax payable or receivable to NRG is reclassified to equity in the same period since GenOn Americas Generation does not have a tax sharing agreement with NRG.

GenOn Americas Generation would not be allocated income taxes attributable to its operations as of June 30,2013 and December 31, 2012, respectively as the income tax expense and benefit relate to FIN 48 reserves for uncertain tax benefits.

GenOn Mid-Atlantic

GenOn Mid-Atlantic and GenOn Mid-Atlantic's subsidiaries are limited liability companies that are treated as branches of NRG Americas for income tax purposes. As a result, NRG Americas, GenOn and NRG have direct liability for the majority of the federal and state income taxes relating to GenOn Mid-Atlantic's operations. If GenOn Mid-Atlantic were to be allocated income taxes attributable to its operations, the pro forma income tax provision attributable to income before taxes would be an expense of $23 million and tax benefit of $22 million during the three months ended June 30,2013 and 2012, respectively. The pro forma income tax provision attributable to income before taxes for the six months ended June 30, 2013 and 2012 would be a tax benefit of $4 million and tax expense of $6 million, respectively. The balance of GenOn Mid-Atlantic's pro forma deferred income taxes would be a net deferred tax asset of $603 million and $598 million as of June 30, 2013 and December 31, 2012, respectively.    

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Note 9 — Related Party Transactions (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Services Agreement with NRG (GenOn)

Subsequent to the NRG Merger, NRG provides GenOn with various management, personnel and other services, which include human resources, regulatory and public affairs, accounting, tax, legal, information systems, treasury, risk management, commercial operations, and asset management, as set forth in the Services Agreement. The initial term of the Services Agreement is through December 31, 2013, with an automatic renewal absent a request for termination. The fee charged is determined based on a fixed amount as described in the Services Agreement and was calculated based on historical GenOn expenses prior to the NRG Merger. The annual fees under the Services Agreement are approximately $193 million. NRG charges these fees on a monthly basis, less amounts incurred directly by GenOn. Management has concluded that this method of charging overhead costs is reasonable. For the three and six months endedJune 30, 2013, GenOn recorded costs related to these services of $14 million and $25 million, respectively, as selling, general and administrative — affiliate.

Administrative Services Provided by NRG for the Successor Period and Provided by GenOn Energy for the Predecessor Period

Prior to the NRG Merger, GenOn provided GenOn Americas Generation and GenOn Mid-Atlantic with various management, personnel and other services directly relating to their facilities. GenOn Americas Generation and GenOn Mid-Atlantic reimbursed GenOn for amounts equal to the costs of providing such services. In addition, GenOn's corporate overhead costs were allocated to its subsidiaries based on each operating subsidiary's planned operating expenses relative to all operating subsidiaries of GenOn. Subsequent to the NRG Merger, NRG provides GenOn Americas Generation and GenOn Mid-Atlantic with various management, personnel and other services consistent with those set forth in the Services Agreement discussed above between NRG and GenOn. GenOn's costs incurred under the Services Agreement with NRG are allocated to its subsidiaries based on each operating subsidiary's planned operating expenses relative to all operating subsidiaries of GenOn. These allocations and charges are not necessarily indicative of what would have been incurred had GenOn Americas Generation and GenOn Mid-Atlantic been unaffiliated entities. Management has concluded that this method of charging overhead costs is reasonable.

The following costs were incurred under these arrangements:

GenOn Americas Generation

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	35	$	38	$	70	$	79
Allocated costs:
Cost of operations — affiliate	1		8		5		17
Selling, general and administrative — affiliate	22		23		42		39
Total	$	58	$	69	$	117	$	135

GenOn Mid-Atlantic

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	21	$	24	$	44	$	48
Allocated costs:
Cost of operations — affiliate	—		2		3		6
Selling, general and administrative — affiliate	17		18		33		30
Total	$	38	$	44	$	80	$	84

In addition, for the successor period, NRG provided services to certain of GenOn's operating subsidiaries including the execution of contracts, including economic hedges to reduce price risk. These transactions are recorded as operating revenues — affiliate and cost of operations — affiliate in GenOn's consolidated statement of operations. Amounts due from and to NRG are recorded as accounts receivable — affiliate or accounts payable — affiliate.

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Services Provided by GenOn Energy Management (GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn Americas Generation

GenOn Energy Management provides services to certain of GenOn's indirect operating subsidiaries through power, fuel supply and services agreements. The services include the bidding and dispatch of the generating units, fuel procurement and the execution of contracts, including economic hedges to reduce price risk. These transactions are recorded as operating revenues — affiliate or cost of operations — affiliate in GenOn Americas Generation's consolidated statements of operations. Amounts due from and to GenOn's indirect operating subsidiaries are recorded as accounts receivable — affiliate or accounts payables — affiliate. Substantially all energy marketing overhead expenses are allocated to GenOn's operating subsidiaries by GenOn Energy Management. For the three months ended June 30, 2013 and 2012, GenOn Americas Generation recorded a reduction to cost of operations — affiliate of $2 million and $6 million, respectively, and for the six months ended June 30, 2013 and 2012, GenOn Americas Generation recorded a reduction to cost of operations — affiliate of $4 million and $12 million, respectively, related to the allocations of energy marketing overhead expenses to affiliates outside of GenOn Americas Generation.

GenOn Mid-Atlantic

GenOn Mid-Atlantic receives services from GenOn Energy Management which include the bidding and dispatch of the generating units, procurement of fuel and other products and the execution of contracts, including economic hedges, to reduce price risk. These transactions are recorded as operating revenues — affiliate or cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations. Amounts due to and from GenOn Energy Management under the power, fuel supply and services agreements are recorded as accounts payables — affiliate or accounts receivables — affiliate. Under these agreements, GenOn Energy Management resells GenOn Mid-Atlantic's energy products in the PJM spot and forward markets and to other third parties. GenOn Mid-Atlantic pays the amount received by GenOn Energy Management for such capacity and energy. GenOn Mid-Atlantic has counterparty credit risk in the event that GenOn Energy Management is unable to collect amounts owed from third parties for the resale of GenOn Mid-Atlantic's energy products. Substantially all energy marketing overhead expenses are allocated to GenOn's operating subsidiaries. For the three months ended June 30, 2013 and 2012, GenOn Mid-Atlantic incurred an insignificant amount and $1 million of energy marketing overhead expense, respectively. For the six months ended June 30, 2013 and 2012, GenOn Mid-Atlantic incurred $1 million and $2 million of energy marketing overhead expense, respectively. These costs were included in cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations.

Credit Agreement with NRG (GenOn)

In connection with the closing of the NRG Merger, GenOn and NRG Americas entered into a secured intercompany revolving credit agreement with NRG.  This credit agreement provides for a $500 million revolving credit facility, all of which is available for revolving loans and letters of credit. At June 30, 2013 and December 31, 2012, letters of credit of $296 million and $261 million, respectively, were issued and outstanding under the NRG credit agreement on behalf of GenOn. At June 30, 2013 and December 31, 2012, letters of credit of $108 million and $166 million, respectively, were issued on behalf of GenOn Americas Generation. At June 30, 2013 and December 31, 2012, letters of credit of $78 million and $113 million, respectively, were issued on behalf of GenOn Mid-Atlantic. At June 30, 2013 and December 31, 2012, no loans were outstanding under this credit agreement.  In connection with the execution of the agreement, certain of GenOn's subsidiaries, as guarantors, entered into a guarantee agreement pursuant to which these guarantors guaranteed amounts borrowed and obligations incurred under the credit agreement. The credit agreement has a three year maturity and is payable at maturity, subject to certain exceptions primarily related to asset sales not in the ordinary course of business and borrowings of debt. In addition, the guarantors are restricted from incurring additional liens on their assets. At GenOn's election, the interest rate per year applicable to the loans under the credit agreement will be determined by reference to either (i) the base rate plus 2.50% per year or (ii) the LIBOR rate plus 3.50% per year. In addition, the credit agreement contains customary covenants and events of default.

Intercompany Cash Management Program (GenOn Americas Generation)

GenOn Americas Generation and certain of its subsidiaries participate in separate intercompany cash management programs whereby cash balances at GenOn Americas Generation and the respective participating subsidiaries are transferred to central concentration accounts to fund working capital and other needs of the respective participants. The balances under this program are reflected as notes receivable — affiliate or notes payable — affiliate, as appropriate. The notes are due on demand and accrue interest on the net position, which is payable quarterly, at the short term yield of the Federated Investors Treasury Obligation Fund or such other fund designated by GenOn Energy Holdings. At June 30, 2013 and December 31, 2012, GenOn Americas Generation had a net current note receivable from GenOn Energy Holdings of $301 million and $198 million, respectively, related to its intercompany cash management program. For the three and six months ended June 30, 2013 and 2012, GenOn Americas Generation earned an insignificant amount of net interest income related to these notes.

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Purchased Emission Allowances (GenOn Mid-Atlantic)

GenOn Energy Management maintains an inventory of certain purchased emission allowances related to the Regional Greenhouse Gas Initiative on behalf of GenOn Mid-Atlantic. The emission allowances are sold by GenOn Energy Management to GenOn Mid-Atlantic as they are needed for operations. GenOn Mid-Atlantic purchases emission allowances from GenOn Energy Management at GenOn Energy Management's original cost to purchase the allowances. For allowances that have been purchased by GenOn Energy Management from a GenOn Energy affiliate, the price paid by GenOn Energy Management is determined by market indices.

Emission allowances purchased from GenOn Energy Management that were utilized during the three months ended June 30, 2013 and 2012 were $4 million and $4 million, respectively, and during the six months ended June 30, 2013 and 2012 were $8 million and $7 million, respectively, and were recorded in cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations.

Sale of NRG Marsh Landing Holdings LLC to NRG Yield LLC (GenOn)

On July 22, 2013, concurrent with the initial public offering of NRG Yield, Inc., GenOn sold its ownership interests in NRG Marsh Landing Holdings LLC to NRG Yield LLC for a purchase price of $199 million. The net assets of NRG Marsh Landing Holdings LLC were $168 million at the time of the sale resulting in the recognition of additional paid-in capital of $31 million.

Note 10 — Commitments and Contingencies (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Contingencies

Set forth below is a description of the Registrants’ material legal proceedings. The Registrants believe that they have valid defenses to these legal proceedings and intend to defend them vigorously. The Registrants record reserves for estimated losses from contingencies when information available indicates that a loss is probable and the amount of the loss, or range of loss, can be reasonably estimated. In addition, legal costs are expensed as incurred. Management has assessed each of the following matters based on current information and made a judgment concerning its potential outcome, considering the nature of the claim, the amount and nature of damages sought, and the probability of success. Unless specified below, the Registrants are unable to predict the outcome of these legal proceedings or reasonably estimate the scope or amount of any associated costs and potential liabilities. As additional information becomes available, management adjusts its assessment and estimates of such contingencies accordingly. Because litigation is subject to inherent uncertainties and unfavorable rulings or developments, it is possible that the ultimate resolution of the Registrants’ liabilities and contingencies could be at amounts that are different from currently recorded reserves and that such difference could be material.

In addition to the legal proceedings noted below, the Registrants are parties to other litigation or legal proceedings arising in the ordinary course of business. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect the Registrants’ respective consolidated financial position, results of operations, or cash flows.

Global Warming (GenOn)

In February 2008, the Native Village of Kivalina and the City of Kivalina, Alaska filed a suit in the U.S. District Court for the Northern District of California against GenOn and 23 other electric generating and oil and gas companies. The lawsuit sought damages of up to $400 million for the cost of relocating the village allegedly because of global warming caused by the greenhouse gas emissions of the defendants. In late 2009, the District Court ordered that the case be dismissed and the plaintiffs appealed. In September 2012, the U.S. Court of Appeals for the Ninth Circuit dismissed plaintiffs’ appeal. In October 2012, the plaintiffs petitioned for en banc rehearing of the case; which petition was denied in November 2012. In February 2013, plaintiffs filed a petition with the U.S. Supreme Court seeking review of the decision from the U.S. Court of Appeals. On May 20, 2013, the U.S. Supreme Court denied plaintiffs petition, thereby ending the case.

Actions Pursued by MC Asset Recovery (GenOn)

With Mirant Corporation's emergence from bankruptcy protection in 2006, certain actions filed by GenOn Energy Holdings and some of its subsidiaries against third parties were transferred to MC Asset Recovery, a wholly owned subsidiary of GenOn Energy Holdings.  MC Asset Recovery is governed by a manager who is independent of NRG and GenOn.  MC Asset Recovery is a disregarded entity for income tax purposes.

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Under one of the remaining actions transferred to MC Asset Recovery, MC Asset Recovery seeks to recover damages from Commerzbank AG and various other banks, or the Commerzbank Defendants, for alleged fraudulent transfers that occurred prior to GenOn Energy Holdings' bankruptcy proceedings.  In December 2010, the United States District Court for the Northern District of Texas dismissed MC Asset Recovery's complaint against the Commerzbank Defendants.  In January 2011, MC Asset Recovery appealed the United States District Court's dismissal of its complaint against the Commerzbank Defendants to the United States Court of Appeals for the Fifth Circuit.  In March 2012, the United States Court of Appeals for the Fifth Circuit reversed the United States District Court's dismissal and reinstated MC Asset Recovery's amended complaint against the Commerzbank Defendants.  If MC Asset Recovery succeeds in obtaining any recoveries from the Commerzbank Defendants, the Commerzbank Defendants have asserted that they will seek to file claims in GenOn Energy Holdings' bankruptcy proceedings for the amount of those recoveries.  GenOn Energy Holdings would vigorously contest the allowance of any such claims. If the Commerzbank Defendants were to receive an allowed claim as a result of a recovery by MC Asset Recovery on its claims against them, GenOn Energy Holdings would retain from the net amount recovered by MC Asset Recovery an amount equal to the dollar amount of the resulting allowed claim.

Pending Natural Gas Litigation (GenOn)

GenOn is party to five lawsuits, several of which are class action lawsuits, in state and federal courts in Kansas, Missouri, Nevada and Wisconsin. These lawsuits were filed in the aftermath of the California energy crisis in 2000 and 2001 and the resulting FERC investigations and relate to alleged conduct to increase natural gas prices in violation of antitrust and similar laws. The lawsuits seek treble or punitive damages, restitution and/or expenses. The lawsuits also name as parties a number of energy companies unaffiliated with GenOn. In July 2011, the U.S. District Court for the District of Nevada, which is handling four of the five cases, granted the defendants’ motion for summary judgment and dismissed all claims against GenOn in those cases. The plaintiffs appealed to the U.S. Court of Appeals for the Ninth Circuit. The Ninth Circuit reversed the decision of the U.S. District Court for the District of Nevada. In September 2012, the State of Nevada Supreme Court, which is handling the remaining case, affirmed dismissal by the Eighth Judicial District Court for Clark County, Nevada of all plaintiffs’ claims against GenOn. In February 2013, the plaintiffs filed a petition for certiorari to the U.S. Supreme Court. On June 24, 2013, the U.S. Supreme Court denied the petition for certiorari, thereby ending one of the five lawsuits. GenOn has agreed to indemnify CenterPoint against certain losses relating to these lawsuits.

New Source Review Matters

The EPA and various states are investigating compliance of coal-fueled electric generating facilities with the pre-construction permitting requirements of the CAA known as “new source review.” Since 2000, the EPA has made information requests concerning the Avon Lake, Chalk Point, Cheswick, Conemaugh, Dickerson, Elrama, Keystone, Morgantown, New Castle, Niles, Portland, Potomac River, Shawville and Titus generating facilities. The Registrants continue to correspond with the EPA regarding some of these requests. The EPA agreed to share information relating to its investigations with state environmental agencies. In January 2009, GenOn received an NOV from the EPA alleging that past work at its Shawville, Portland and Keystone generating facilities violated regulations regarding new source review. In June 2011, GenOn received an NOV from the EPA alleging that past work at the Niles and Avon Lake generating facilities violated regulations regarding new source review.

In December 2007, the NJDEP sued GenOn in the U.S. District Court for the Eastern District of Pennsylvania, alleging that new source review violations occurred at the Portland generating facility. The suit sought installation of “best available” control technologies for each pollutant, to enjoin GenOn from operating the generating facility if it is not in compliance with the CAA and civil penalties. The suit also named past owners of the plant as defendants, but the claims against the past owners have since been dismissed. In March 2009, the Connecticut Department of Energy and Environmental Protection became an intervening party to the suit. GenOn believes that the work listed by the EPA and the work subject to the NJDEP suit were conducted in compliance with applicable regulations. The parties appeared for mediation before the magistrate judge on April 10, 2013. The parties reached a settlement in principle of this matter on that date. On May 15, 2013, the parties submitted an agreed upon proposed Consent Decree to the court. No objections to the proposed Consent Decree were filed. On July 18, 2013, the court entered the Consent Decree resolving the matter.

In addition, the NJDEP filed two administrative petitions with the EPA in 2010 alleging that the Portland generating facility’s emissions were significantly contributing to nonattainment and/or interfering with the maintenance of certain NAAQS in New Jersey. In November 2011, the EPA published a final rule in response to one of the petitions that required GenOn to reduce maximum allowable SO₂ emissions from the two coal-fired units by about 60% starting in January 2013. In January 2012, GenOn challenged the rule in the U.S. Court of Appeals for the Third Circuit. On July 12, 2013, the Third Circuit denied GenOn's petition seeking review. GenOn has several compliance options until June 1, 2014 that include using lower sulfur coals (although this may at times reduce how much GenOn is able to generate) or running just one unit at a time.

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Cheswick Class Action Complaint (GenOn)

In April 2012, a putative class action lawsuit was filed against GenOn in the Court of Common Pleas of Allegheny County, Pennsylvania alleging that emissions from the Cheswick generating facility have damaged the property of neighboring residents.  GenOn disputes these allegations.  Plaintiffs have brought nuisance, negligence, trespass and strict liability claims seeking both damages and injunctive relief.  Plaintiffs seek to certify a class that consists of people who own property or live within one mile of the plant. In July 2012, GenOn removed the lawsuit to the U.S. District Court for the Western District of Pennsylvania. In October 2012, the court granted GenOn’s motion to dismiss, which Plaintiffs have appealed to the U.S. Court of Appeals for the Third Circuit. The Third Circuit heard oral argument on June 25, 2013.

Cheswick Monarch Mine NOV(GenOn)

In 2008, the PADEP issued an NOV related to the Monarch mine located near the Cheswick generating facility. It has not been mined for many years. GenOn uses it for disposal of low-volume wastewater from the Cheswick generating facility and for disposal of leachate collected from ash disposal facilities. The NOV addresses the alleged requirement to maintain a minimum pumping volume from the mine. The PADEP indicated it may assess a civil penalty in excess of $100,000. GenOn contests the allegations in the NOV and has not agreed to such penalty. GenOn is currently planning capital expenditures in connection with wastewater from Cheswick and leachate from ash disposal facilities.

Ormond Beach Alleged Federal Clean Water Act Violations (GenOn)

In October 2012, the Wishtoyo Foundation, a California-based cultural and environmental advocacy organization, through its Ventura Coastkeeper Program, filed suit in the U.S. District Court for the Central District of California regarding alleged violations of the Clean Water Act associated with discharges of stormwater from the Ormond Beach generating facility. The Wishtoyo Foundation alleges that elevated concentrations of pollutants in stormwater discharged from the Ormond Beach generating facility were affecting adjacent aquatic resources in violation of (i) the Statewide General Industrial Stormwater permit (a general National Pollution Discharge Elimination System permit issued by the California State Water Resources Control Board that authorizes stormwater discharges from industrial facilities in California) and (ii) the state’s Porter-Cologne Water Quality Control Act. The Wishtoyo Foundation further alleged that GenOn had not implemented effective stormwater control and treatment measures and that GenOn had not complied with the sampling and reporting requirements of the General Industrial Stormwater permit. GenOn settled this matter in May 2013 and agreed to make operational changes and pay $79,000 in legal fees, $65,000 for supplemental environmental projects and $15,000 for monitoring costs.

Maryland Fly Ash Facilities

GenOn MD Ash Management has three fly ash facilities in Maryland: Faulkner, Westland and Brandywine. GenOn MD Ash Management disposes of fly ash from the Morgantown and Chalk Point generating facilities at Brandywine. GenOn MD Ash Management disposes of fly ash from the Dickerson generating facility at Westland. GenOn MD Ash Management no longer disposes of fly ash at the Faulkner facility. As described below, the MDE had sued GenOn MD Ash Management and GenOn Mid-Atlantic regarding Faulkner, Brandywine and Westland. The MDE also had threatened not to renew the water discharge permits for all three facilities.

Faulkner Litigation. In May 2008, the MDE sued GenOn Mid-Atlantic and GenOn MD Ash Management in the Circuit Court for Charles County, Maryland alleging violations of Maryland’s water pollution laws at Faulkner. The MDE contended that the operation of Faulkner had resulted in the discharge of pollutants that exceeded Maryland’s water quality criteria and without the appropriate NPDES permit. The MDE also alleged that GenOn failed to perform certain sampling and reporting required under an applicable NPDES permit. The MDE complaint requested that the court (i) prohibit continuation of the alleged unpermitted discharges, (ii) require GenOn to cease from further disposal of any coal combustion byproducts at Faulkner and close and cap the existing disposal cells and (iii) assess civil penalties. In July 2008, GenOn filed a motion to dismiss the complaint, arguing that the discharges are permitted by a December 2000 Consent Order. In January 2011, the MDE dismissed without prejudice its complaint and informed GenOn that it intended to file a similar lawsuit in federal court. In May 2011, the MDE filed a complaint against GenOn Mid-Atlantic and GenOn MD Ash Management in the U.S. District Court for the District of Maryland alleging violations at Faulkner of the Clean Water Act and Maryland’s Water Pollution Control Law. The MDE contends that (i) certain of GenOn's water discharges are not authorized by the existing permit and (ii) operation of the Faulkner facility has resulted in discharges of pollutants that violate water quality criteria. The complaint asked the court to, among other things, (i) enjoin further disposal of coal ash; (ii) enjoin discharges that are not authorized by the existing permit; (iii) require numerous technical studies; (iv) impose civil penalties and (v) award MDE attorneys’ fees. GenOn disputed these allegations.

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Brandywine Litigation. In April 2010, the MDE filed a complaint against GenOn Mid-Atlantic and GenOn MD Ash Management in the U.S. District Court for the District of Maryland asserting violations at Brandywine of the Clean Water Act and Maryland’s Water Pollution Control Law. The MDE contended that the operation of Brandywine has resulted in discharges of pollutants that violate Maryland’s water quality criteria. The complaint requested that the court, among other things, (i) enjoin further disposal of coal combustion waste at Brandywine, (ii) require GenOn to close and cap the existing open disposal cells within one year, (iii) impose civil penalties and (iv) award MDE attorneys’ fees. GenOn disputed the allegations. In September 2010, four environmental advocacy groups became intervening parties in the proceeding.

Westland Litigation. In January 2011, the MDE informed GenOn that it intended to sue for alleged violations at Westland of Maryland’s water pollution laws, which suit was filed in the U.S. District Court for the District of Maryland in December 2012.

Permit Renewals. In March 2011, the MDE tentatively determined to deny GenOn MD Ash Management's application for the renewal of the water discharge permit for Brandywine, which could result in a significant increase in operating expenses for the Chalk Point and Morgantown generating facilities. The MDE also had indicated that it was planning to deny GenOn’s applications for the renewal of the water discharge permits for Faulkner and Westland. Denial of the renewal of the water discharge permit for the latter facility could have resulted in a significant increase in operating expenses for GenOn Mid-Atlantic's Dickerson generating facility.

Settlement. In June 2011, the MDE agreed to stay the litigation related to Faulkner and Brandywine while GenOn pursued settlement of allegations related to the three Maryland ash facilities. MDE also agreed not to pursue its tentative denial of GenOn’s application to renew the water discharge permit at Brandywine and agreed not to act on GenOn’s renewal applications for Faulkner or Westland while GenOn was discussing settlement. As a condition to obtaining the stay, GenOn agreed in principle to pay a civil penalty of $1.9 million (for alleged past violations) to the MDE if GenOn reached a comprehensive settlement regarding all of the allegations related to the three Maryland ash facilities. GenOn accrued $1.9 million during 2011 and an additional $0.6 million (for agreed prospective penalties while GenOn implements the settlement) during the second quarter of 2012 for a total of $2.5 million. GenOn also developed a technical solution, which includes installing synthetic caps on the closed cells of each of the three ash facilities. During 2011, GenOn accrued $47 million for the estimated cost of the technical solution. At this time, GenOn cannot reasonably estimate the upper range of its obligations for remediating the sites because GenOn has not (i) finished assessing each site including identifying the full impacts to both ground and surface water and the impacts to the surrounding habitat; (ii) finalized with the MDE the standards to which it must remediate; and (iii) identified the technologies required, if any, to meet the yet to be determined remediation standards at each site nor the timing of the design and installation of such technologies. A hearing was held on March 18, 2013 on entry of the Consent Decree. In April2013, GenOn MD Ash Management and MDE signed a slightly revised consent decree, which was approved by the court on April 30, 2013. Accordingly, these issues have been resolved.

Purported Class Actions related to July 22, 2012 Announcement of NRG Merger Agreement (GenOn)

GenOn was named as a defendant in eight purported class actions in Texas and Delaware, related to its announcement of its agreement for NRG to acquire all outstanding shares of GenOn. These cases were consolidated into one state court case in each of Delaware and Texas and a federal court case in Texas. The plaintiffs generally alleged breach of fiduciary duties, as well as conspiracy, aiding and abetting breaches of fiduciary duties. Plaintiffs generally sought to: be certified as a class; enjoin the merger; direct the defendants to exercise their fiduciary duties; rescind the acquisition and be awarded attorneys' fees and costs and other relief that the court deems appropriate. Plaintiffs also demanded that there be additional disclosures regarding the merger terms. On October 24, 2012, the parties to the Delaware state court case executed a Memorandum of Understanding to resolve the Delaware purported class action lawsuit. In March 2013, the parties finalized the settlement of the Delaware action. On June 3, 2013, the court approved the Delaware class action settlement thereby ending the Delaware lawsuit.

Maryland Department of the Environment v. GenOn Chalk Point and GenOn Mid-Atlantic

In January 2013, Food & Water Watch, the Patuxent Riverkeeper and the Potomac Riverkeeper (together, Citizens Group) sent GenOn Mid-Atlantic a letter alleging that the Chalk Point, Dickerson and Morgantown generating facilities were violating the terms of three National Pollution Discharge Elimination System Permits by discharging nitrogen and phosphorous in excess of the limits in each permit. On March 21, 2013 the MDE sent the Company a similar letter with respect to the Chalk Point and Dickerson facilities, threatening to sue within 60 days if the facilities were not brought into compliance. On June 11, 2013, the Maryland Attorney General on behalf of the MDE filed a complaint in the United States District Court for the District of Maryland alleging violations of the Clean Water Act and Maryland environmental laws related to water. The lawsuit seeks injunctive relief and civil penalties.

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Chapter 11 Proceedings (GenOn and GenOn Americas Generation)

In July 2003, and various dates thereafter, the Mirant Debtors filed voluntary petitions in the Bankruptcy Court for relief under Chapter 11 of the U.S. Bankruptcy Code. GenOn Energy Holdings and most of the other Mirant Debtors emerged from bankruptcy on January 3, 2006, when the Plan became effective. The remaining Mirant Debtors emerged from bankruptcy on various dates in 2007. Approximately 461,000 of the shares of GenOn Energy Holdings common stock to be distributed under the Plan have not yet been distributed and have been reserved for distribution with respect to claims disputed by the Mirant Debtors that have not been resolved. Upon the Mirant/RRI Merger, those reserved shares converted into a reserve for approximately 1.3 million shares of GenOn common stock. Upon the NRG Merger, those reserved shares converted into a reserve for approximately 159,000 shares of NRG common stock. Under the terms of the Plan, upon the resolution of such a disputed claim, the claimant will receive the same pro rata distributions of common stock, cash, or both as previously allowed claims, regardless of the price at which the common stock is trading at the time the claim is resolved. If the aggregate amount of any such payouts results in the number of reserved shares being insufficient, additional shares of common stock may be issued to address the shortfall.

Texas Franchise Audit (GenOn)

During the second quarter of 2013, GenOn settled the Texas Franchise tax dispute with the state relating to years 2001 through 2007. Prior to NRG Merger, the State of Texas issued franchise tax assessments against GenOn as a result of its audit indicating an underpayment of franchise tax of $72 million (including interest and penalties through June 30, 2013 of $29 million). These assessments relate primarily to a claim by Texas that would change the sourcing of intercompany receipts thereby increasing the amount of tax due. GenOn disagreed with most of the State's assessment and its determination and had accordingly accrued a portion of the liability but had protested the entire assessment.  In June 2013, the Company settled the matter with the State by agreeing to pay $11 million on issues arising from the audit, and reversed the remainder of the accrual. The reversal was recorded as a measurement period adjustment to the amounts recognized on the acquisition date.

Note 11 — Regulatory Matters (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The Registrants operate in a highly regulated industry and are subject to regulation by various federal and state agencies. As such, the Registrants are affected by regulatory developments at both the federal and state levels and in the regions in which they operate. In addition, the Registrants are subject to the market rules, procedures, and protocols of the various ISO markets in which they participate. These power markets are subject to ongoing legislative and regulatory changes that may impact the Registrants.

In addition to the regulatory proceedings noted below, the Registrants are a party to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect the Registrants’ respective consolidated financial position, results of operations, or cash flows.

East Region (GenOn)

RMR Agreements for Elrama and Niles — In May 2012, GenOn filed with FERC an RMR rate schedule governing operation of unit 4 of the Elrama generating facility and unit 1 of the Niles generating facility.  PJM determined that each of these units was needed past its planned deactivation date of June 1, 2012 to maintain transmission system reliability on the PJM system pending the completion of transmission upgrades.  The RMR rate schedule sets forth the terms, conditions and cost-based rates under which GenOn operated the units for reliability purposes through September 30, 2012, the date PJM indicated the units would no longer be needed for reliability.  In July 2012, FERC accepted GenOn's RMR rate schedule subject to hearing and settlement procedures.  In the settlement discussions ordered by FERC, or in any subsequent hearing, GenOn's RMR rate schedule may be modified from that which was filed.  The rates GenOn charged are subject to refund pending a ruling or settlement. GenOn filed a settlement of all outstanding issues in May 2013, which several parties are contesting. Any eventual settlement must be approved by FERC.

39

Note 12 — Environmental Matters (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The Registrants are subject to a wide range of environmental regulations in the development, ownership, construction and operation of projects. These laws and regulations generally require that governmental permits and approvals be obtained before construction and during operation of power plants. Environmental regulations have become increasingly stringent and the Registrants expect this trend to continue. The electric generation industry is likely to face new requirements to address various emissions, including greenhouse gases, as well as combustion byproducts, water discharge and use, and threatened and endangered species. In general, future laws and regulations are expected to require the addition of emissions controls or other environmental quality equipment or the imposition of certain restrictions on the operations of the Registrants' facilities, which could have a material effect on the Registrants' operations.

Environmental Capital Expenditures

Based on current rules, technology and plans based on proposed rules, GenOn estimates that environmental capital expenditures from 2013 through 2017 required to meet GenOn's regulatory environmental laws will be approximately $208 million for GenOn, which includes $46 million for GenOn Americas Generation. The amount for GenOn Americas Generation includes $4 million for GenOn Mid-Atlantic. These costs are primarily associated with controls to satisfy MATS at Conemaugh and NO_x controls for Sayreville and Gilbert. The Registrants continue to explore cost effective compliance alternatives to further reduce costs.

East Region

The EPA and various states are investigating compliance of coal-fueled electric generating facilities with the pre-construction permitting requirements of the CAA known as NSR. In January 2009, GenOn received an NOV from the EPA alleging that past work at Keystone, Portland and Shawville generating stations violated regulations regarding NSR. In June 2011, GenOn received an NOV from the EPA alleging that past work at Avon Lake and Niles generating stations violated NSR. In December 2007, the NJDEP filed suit alleging that NSR violations occurred at the Portland generating station. GenOn believes the suits are without merit and the subject work was conducted in compliance with applicable regulations. The Shawville, Niles and Portland generating units that are the subject of the NOVs are scheduled for retirement soon.

In 2008, the PADEP issued an NOV related to the inactive Monarch mine where low-volume wastewater from GenOn's Cheswick Generating Station and ash leachate was historically disposed. Resolution of the NOV could result in operational requirements such as pumping a minimum volume of water from the mine and a penalty in excess of $100,000.

The MDE sued GenOn Mid-Atlantic and GenOn MD Ash Management for alleged violations of water pollution laws at three fly ash disposal sites in Maryland: Faulkner (2008/2011), Brandywine (2010) and Westland (2012). On April 30, 2013, the court approved the consent decree resolving these issues. GenOn MD Ash Management has since discontinued use of the Faulkner disposal site and opened a new, state of the art carbon burnout facility at the Morgantown plant that allows greater beneficial reuse (as a cement substitute).

For further discussion of these matters, refer to Note 10, Commitments and Contingencies.

40

Item 2 — MANAGEMENT'S NARRATIVE ANALYSIS OF THE RESULTS OF OPERATIONS AND FINANCIAL CONDITION (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

As you read this discussion and analysis, refer to the Registrants' Condensed Consolidated Financial Statements to this Form 10-Q, which present the results of operations for the three and six months ended June 30, 2013 and 2012. Also, refer to the Registrants' 2012 Form 10-K, which includes detailed discussions of various items impacting the Registrants' business, results of operations and financial condition.

NRG Merger

On December 14, 2012, NRG completed the acquisition of GenOn.  NRG issued, as consideration for the acquisition, 0.1216 shares of NRG common stock for each outstanding share of GenOn, including restricted stock units outstanding, on the acquisition date, except for fractional shares which were paid in cash. See Note 3, NRG Merger, to the Condensed Consolidated Financial Statements.

The NRG Merger was accounted for by NRG using acquisition accounting and through the application of “push-down” accounting, the purchase price paid by NRG was allocated to the Registrants' assets, liabilities and equity as of the acquisition date based upon preliminary estimates. Accordingly, the successor financial statements reflect a new basis of accounting and predecessor and successor period financial results are presented, but not comparable.

The most significant impacts of the new basis of accounting during the successor periods were (i) reduced depreciation expense due to the step-down of depreciable assets, (ii) lower interest expense for the remaining life of long-term debt due to its revaluation and related debt premium amortization along with the repayment of the senior secured term loan due 2017, and (iii) reduced cost of operations due to the amortization of lease obligations and out-of-market contracts.

The results of operations for successor periods included herein reflect certain acquisition-related transaction and integration costs which are not expected to have a continuing impact on the results going forward, and those amounts are included within a separate line within the Registrants' consolidated results of operations.

Predecessor and Successor Reporting

As a result of the impact of pushdown accounting, the financial statements and certain note presentations separate GenOn’s, GenOn Americas Generation’s and GenOn Mid-Atlantic’s presentations into two distinct periods, the period before the consummation of the NRG Merger (labeled predecessor) and the period after that date (labeled successor), to indicate the application of different basis of accounting between the periods presented.

Environmental Matters

The Registrants are subject to a wide range of environmental regulations in the development, ownership, construction and operation of projects. These laws and regulations generally require that governmental permits and approvals be obtained before construction and during operation of power plants. Environmental regulations have become increasingly stringent and the Registrants expect this trend to continue. The electric generation industry is likely to face new requirements to address various emissions, including greenhouse gases, as well as combustion byproducts, water discharge and use, and threatened and endangered species. In general, future laws and regulations are expected to require the addition of emissions controls or other environmental quality equipment or the imposition of certain restrictions on the operations of the Registrants' facilities, which could have a material effect on the Registrants' operations. Complying with environmental requirements involves significant capital and operating expenses. The Registrants decide to invest capital for environmental controls based on relative certainty of the requirements, an evaluation of compliance options, and the expected economic returns on capital. See Note 10, Commitments and Contingencies and Note 12,Environmental Matters, to the Condensed Consolidated Financial Statements for further discussion.

East Region

RGGI — In February 2013, RGGI, Inc. released a proposed model rule that if promulgated by the nine RGGI member states, would reduce the CO₂ emissions cap from 165 million tons to 91 million tons in 2014 with a 2.5% reduction each year from 2015 to 2020. Each of Connecticut, Maryland, Massachusetts, New York, and Vermont have published a proposed rule. Each of the RGGI states may finalize these regulations later this year. If this occurs, the Registrants expect earnings at their plants in Massachusetts, New York, and particularly those in Maryland, to be negatively affected. The extent to which they would be negatively affected depends on the price of the CO₂ emissions allowances, which in turn will be significantly influenced by future natural gas prices, power prices, generation resource mix, dispatch order, and any nuclear plant retirements.

41

Regulatory Matters

As operators of power plants and participants in wholesale energy markets, certain of the Registrants' entities are subject to regulation by various federal and state government agencies. These include the Commodities Futures Trading Commission and FERC, as well as other public utility commissions in certain states where the Registrants' generating assets are located. In addition, the Registrants are subject to the market rules, procedures and protocols of the various ISO markets in which they participate. The Registrants must also comply with the mandatory reliability requirements imposed by NERC and the regional reliability entities in the regions where they operate.

East Region

PJM

Minimum Offer Price Rule, or MORP, Litigation — On April 12, 2011, FERC issued an order addressing a complaint filed by PJM Power Providers Group seeking to require PJM to address the potential adverse impacts of out-of-market generation on the PJM Reliability Pricing Model, capacity market, as well as PJM's subsequent submission seeking revisions to the capacity market design, in particular the MOPR. In its order, FERC generally strengthened the MOPR and the protections against market price distortion from out-of-market generation. On November 17, 2011, FERC largely denied rehearing of its April 12, 2011 order. Several parties have appealed FERC's decision to federal court, and those appeals have been consolidated in the Third Circuit Court of Appeals. The outcome of this proceeding could drive future capacity prices.

MOPR Revisions — On December 7, 2012, PJM filed comprehensive revisions to its MOPR rules at FERC. On May 2, 2013, FERC accepted PJM's proposal in part, and rejected it in part. Among other things, FERC approved the portions of the PJM proposal that exempt many new entrants from MOPR rules, including projects proposed by merchant generators, public power entities and certain self-supply entities. This exemption is subject to certain conditions designed to limit the financial incentive of such entities to suppress market prices. However, FERC rejected PJM's proposal to eliminate the unit specific review process, and instead directed PJM to continue allowing units to demonstrate their actual costs and revenues, and bid into the auction at that price. On June 3, 2013, NRG filed a request for rehearing of the FERC order and subsequently protested the manner in which PJM proposed to implement the FERC order. These challenges are both pending.

New England (GenOn and GenOn Americas Generation)

New England Power Generators Association, or NEPGA, Complaint — On May 17, 2013, the NEPGA, filed a complaint against ISO New England, Inc., or ISO-NE, asking FERC to clarify that under ISO-NE's existing tariff, a capacity resource's inability to procure or schedule fuel when called upon is not a tariff violation or an attempt to manipulate the ISO-NE energy markets. As an operator of gas fired generation facilities in New England, GenOn Americas Generation could be subject to sanction when gas is not available, unless FERC grants the NEPGA complaint. GenOn Americas Generation supports the NEPGA complaint. ISO-NE answered the NEPGA complaint and the matter is pending.

West Region (GenOn and GenOn Americas Generation)

The California Independent System Operator, or CAISO, and California Public Utilities Commission, or CPUC, launched a joint stakeholder initiative to develop a multiyear reliability market framework. In a whitepaper issued on July 10, 2013, the CAISO/CPUC proposed a joint reliability framework that combined multi-year resource adequacy obligations for Load Serving Entities with a multi-year market-based CAISO backstop capacity procurement mechanism. Specifically, the proposal (i) retains the current one-year forward system and local capacity procurement obligations and extends those procurement obligations to system, local and flexible capacity for two and three years forward; (ii) develops a CAISO-run capacity auction; and (iii) provides for an annual long-term reliability planning assessment focusing on the four to ten-year forward period. The CAISO and CPUC held a joint workshop to discuss the proposal on July 17, 2013, and stakeholders, including NRG, filed comments on the proposal on July 25, 2013. While the whitepaper lacks specificity, GenOn and GenOn Americas Generation view any attempt to extend the procurement obligations forward, and adopt a market structure to help meet those obligations, as a potentially positive step.

South Central Region (GenOn)

On July 5, 2013, AmerenEnergy Resources Generating Company, or Ameren, filed a complaint against MISO pertaining to the compensation for generators asked by MISO to provide service past their retirement date due to reliability concerns. Ameren asked FERC to require MISO to provide such generators their full cost of service as compensation and not merely cover the generator's incremental costs of operation going-forward costs. GenOn supports the Ameren complaint. The matter remains pending.

42

New and On-going Company Initiatives

Operational Improvement Activities

NRG has announced its intention to continue operations at the Avon Lake and New Castle facilities, which are currently in operation and had been scheduled for deactivation in April 2015. NRG intends to add natural gas capabilities at these facilities, which is expected to be completed by the summer of 2016. Additionally, NRG has accelerated the deactivation of the Portland and Titus facilities to 2014 and 2013, respectively.

Changes in Accounting Standards

See Note 2, Summary of Significant Accounting Policies, to this Form 10-Q as found in Item 1 for a discussion of recent accounting developments.

43

Consolidated Results of Operations

GenOn

The following table provides selected financial information for GenOn:

	Successor			Predecessor					Successor			Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013			Three months ended June 30, 2012			Change %		Six months ended June 30, 2013			Six months ended June 30, 2012			Change %
Operating Revenues
Energy revenue (a)	$	424		$	400		6	%	$	908		$	788		15	%
Capacity revenue (a)	246			185			33		409			359			14
Mark-to-market for economic hedging activities	44			(113		)	139		(190		)	37			N/M
Other revenues (b)	11			49			(78	)	28			58			(52	)
Total operating revenues	725			521			39		1,155			1,242			(7	)
Operating Costs and Expenses
Generation cost of sales (a)	262			284			(8	)	553			530			4
Mark-to-market for economic hedging activities	(18		)	40			(145	)	(31		)	83			(137	)
Contract and emissions credit amortization	(12		)	(17		)	29		(19		)	(29		)	34
Other cost of operations	223			199			12		442			450			(2	)
Total cost of operations	455			506			(10	)	945			1,034			(9	)
Depreciation and amortization	62			90			(31	)	121			178			(32	)
Selling, general and administrative	21			64			(67	)	54			114			(53	)
Selling, general and administrative - affiliate	19			—			N/M		36			—			N/M
Acquisition-related transaction and integration costs	22			—			N/M		41			—			N/M
Total operating costs and expenses	579			660			(12	)	1,197			1,326			(10	)
Operating Income/(Loss)	146			(139		)	205		(42		)	(84		)	50
Other Income/(Expense)
Other income, net	—			—			N/M		2			2			—
Interest expense	(56		)	(85		)	(34	)	(103		)	(174		)	(41	)
Loss on debt extinguishment	(11		)	—			N/M		(11		)	—			N/M
Total other expense	(67		)	(85		)	(21	)	(112		)	(172		)	(35	)
Income/(Loss) Before Income Taxes	79			(224		)	135		(154		)	(256		)	40
Income tax (benefit)/expense	(6		)	4			(250	)	(6		)	4			(250	)
Net Income/(Loss)	$	85		$	(228	)	137		$	(148	)	$	(260	)	43
Business Metrics
Average natural gas price — Henry Hub ($/MMBtu)	$	4.09		$	2.22		84	%	$	3.71		$	2.48		50	%
MWh sold (in thousands)	6,828			6,686					14,579			12,347
MWh generated (in thousands)	7,425			6,942					15,592			12,628

(a) Includes realized gains and losses from financially settled transactions.

(b) Includes unrealized trading gains and losses.

N/M - Not meaningful

44

Generation Gross Margin

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Energy revenue	$	424	$	400	$	908	$	788
Capacity revenue	246		185		409		359
Other revenues	11		49		28		58
Generation revenue	681		634		1,345		1,205
Generation cost of sales	262		284		553		530
Generation gross margin	$	419	$	350	$	792	$	675

Generation gross marginincreased by $69 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Higher gross margin due to an 8% increase in generation resulting primarily from Marsh Landing coming online in May 2013, higher generation at Ormond Beach and fewer outages at Bowline as well as a 20% increase in average realized prices	$	40
Higher gross margin from a decrease in purchased energy due to the expiration of tolling agreements	39
Changes in unrealized commercial optimization activities	(10		)
	$	69

Generation gross marginincreased by $117 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Higher gross margin due to an 24% increase in generation resulting primarily from Marsh Landing coming online in May 2013, higher generation at Ormond Beach and fewer outages at Bowline as well as a 5% increase in average realized prices	$	84
Higher gross margin from a decrease in purchased energy due to the expiration of tolling agreements	34
Other	(1		)
	$	117

Mark-to-market for Economic Hedging Activities

Mark-to-market for economic hedging activities includes asset-backed hedges that have not been designated as cash flow hedges. Total net mark-to-market results increased by $215 million and decreased by $113 million for the three and six months ended June 30, 2013, respectively, compared to the same periods in 2012.

The breakdown of gains and losses included in operating revenues and operating costs and expenses are as follows:

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Mark-to-market results in operating revenues
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(111	)	$	(136	)	$	(224	)	$	(292	)
Net unrealized gains on open positions related to economic hedges	155			23			34			329
Total mark-to-market gains/(losses) in operating revenues	$	44		$	(113	)	$	(190	)	$	37
Mark-to-market results in operating costs and expenses
Reversal of previously recognized unrealized losses on settled positions related to economic hedges	12			37			27			64
Net unrealized gains/(losses) on open positions related to economic hedges	6			(77		)	4			(147		)
Total mark-to-market gains/(losses) in operating costs and expenses	$	18		$	(40	)	$	31		$	(83	)

45

Mark-to-market results consist of unrealized gains and losses. The settlement of these transactions is reflected in the same caption as the items being hedged.

For the six months ended June 30, 2013, the loss in operating revenues from economic hedge positions was driven by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period offset by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain in operating costs and expenses from economic hedge positions was primarily driven by the reversal of previously recognized unrealized losses from fuel contracts that settled during the period. 

For the six months ended June 30, 2012, the gain in operating revenues from economic hedge positions was driven by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain was offset by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period. The loss in operating costs and expenses from economic hedge positions was driven by a decrease in the value of forward purchases of fuel contracts, primarily as a result of decreases in forward coal prices. The loss was partially offset by the reversal of previously recognized unrealized losses from fuel contracts that settled during the period.

In accordance with ASC 815, the following table represents the results of GenOn's financial and physical trading of energy commodities. The realized and unrealized financial and physical trading results are included in other operating revenues. GenOn's trading activities are subject to limits within the risk management policy.

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Trading gains/(losses)
Realized	$	2	$	—	$	2	$	(5	)
Unrealized	1		11		—		4
Total trading gains/(losses)	$	3	$	11	$	2	$	(1	)

Other Cost of Operations

Other cost of operations increased by $24 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Reversal of liability for Potomac River in connection with its deactivation	$	31
Decrease in operating costs primarily related to timing of maintenance work	(7		)
	$	24

Other cost of operations decreased by $8 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Decrease as prior year included inventory reserves for units already deactivated or scheduled to be deactivated	$	(35	)
Reversal of liability for Potomac River in connection with its deactivation	31
Other	(4		)
	$	(8	)

46

Acquisition-related Transaction and Integration Costs

Acquisition-related transaction and integration costs of $22 million and $41 million were incurred in the three months and six months ended June 30, 2013 and consisted primarily of severance costs.

Depreciation and Amortization

Depreciation and amortization expense decreased by $28 million and $57 million for the three and six months ended June 30, 2013, respectively, compared to the same period in 2012, which reflects the revaluation of the property, plant and equipment recorded in acquisition accounting in December 2012.

Interest Expense

Interest expense decreased by $29 million during the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Amortization of adjustments to fair value of debt	$	(22	)
Decrease for GenOn senior term loan	(10		)
Increase for NRG Marsh Landing senior term loans	4
Other	(1		)
	$	(29	)

Interest expense decreased by $71 million during the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Amortization of adjustments to fair value of debt	$	(45	)
Decrease for GenOn senior term loan	(20		)
Decrease for higher capitalized interest	(7		)
Increase for NRG Marsh Landing senior term loans	7
Other	(6		)
	$	(71	)

47

GenOn Americas Generation

The following table provides selected financial information for GenOn Americas Generation:

	Successor			Predecessor					Successor			Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013			Three months ended June 30, 2012			Change %		Six months ended June 30, 2013			Six months ended June 30, 2012			Change %
Operating Revenues
Energy revenue (a)	$	419		$	395		6	%	$	892		$	779		15	%
Capacity revenue (a)	212			160			33		361			313			15
Mark-to-market for economic hedging activities	(3		)	(79		)	96		(153		)	3			N/M
Other revenues (b)	10			78			(87	)	70			111			(37	)
Total operating revenues	638			554			15		1,170			1,206			(3	)
Operating Costs and Expenses
Generation cost of sales (a)	443			414			7		901			793			14
Mark-to-market for economic hedging activities	(14		)	40			(135	)	(30		)	66			(145	)
Other cost of operations	107			90			19		212			211			—
Total cost of operations	536			544			(1	)	1,083			1,070			1
Depreciation and amortization	20			41			(51	)	41			81			(49	)
Selling, general and administrative	23			28			(18	)	44			49			(10	)
Total operating costs and expenses	579			613			(6	)	1,168			1,200			(3	)
Operating Income/(Loss)	59			(59		)	200		2			6			(67	)
Other Expense
Interest expense	(18		)	(20		)	(10	)	(36		)	(39		)	(8	)
Total other expense	(18		)	(20		)	(10	)	(36		)	(39		)	(8	)
Income/(Loss) Before Income Taxes	41			(79		)	152		(34		)	(33		)	(3	)
Income taxes	—			—			N/M		—			—			N/M
Net Income/(Loss)	$	41		$	(79	)	152		$	(34	)	$	(33	)	(3	)
Business Metrics
Average natural gas price — Henry Hub ($/MMBtu)	$	4.09		$	2.22		84	%	$	3.71		$	2.48		50	%
MWh sold (in thousands)	1,957			3,173					4,598			5,000
MWh generated (in thousands)	2,016			3,201					4,708			5,022

(a)    Includes realized gains and losses from financially settled transactions.

(b)    Includes unrealized trading gains and losses.

N/M - Not meaningful

48

Generation Gross Margin

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Energy revenue	$	419	$	395	$	892	$	779
Capacity revenue	212		160		361		313
Other revenues	10		78		70		111
Generation revenue	641		633		1,323		1,203
Generation cost of sales	443		414		901		793
Generation gross margin	$	198	$	219	$	422	$	410

Generation gross margin decreased by $21 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Lower gross margin due to a 39% decrease in generation resulting from the deactivation of Potomac River and outages at Chalk Point, partially offset by a 40% increase in average realized prices	$	(18	)
Higher capacity revenues due primarily to a 29% increase in capacity prices	18
Primarily reflects activities that were transitioned to NRG or affiliated companies in the current year	(18		)
Other	(3		)
	$	(21	)

Generation gross margin increased by $12 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Higher capacity revenues due primarily to a 24% increase in capacity prices	$	27
Lower gross margin due to a 15% decrease in generation resulting from the deactivation of Potomac River and outages at Chalk Point, partially offset by a 10% increase in average realized prices	(16		)
Primarily reflects activities that were transitioned to NRG or affiliated companies in the current year	9
Other	(8		)
	$	12

Mark-to-market for Economic Hedging Activities

Mark-to-market for economic hedging activities includes asset-backed hedges that have not been designated as cash flow hedges. Total net mark-to-market results increased by $130 million and decreased by $60 million for the three and six months ended June 30, 2013, respectively, compared to the same periods in 2012.

The breakdown of gains and losses included in operating revenues and operating costs and expenses are as follows:

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Mark-to-market results in operating revenues
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(86	)	$	(106	)	$	(175	)	$	(230	)
Net unrealized gains on open positions related to economic hedges	83			27			22			233
Total mark-to-market (losses)/gains in operating revenues	(3		)	(79		)	(153		)	3
Mark-to-market results in operating costs and expenses
Reversal of previously recognized unrealized losses on settled positions related to economic hedges	11			33			26			57
Net unrealized gains/(losses) on open positions related to economic hedges	3			(73		)	4			(123		)
Total mark-to-market gains/(losses) in operating costs and expenses	$	14		$	(40	)	$	30		$	(66	)

49

Mark-to-market results consist of unrealized gains and losses. The settlement of these transactions is reflected in the same caption as the items being hedged.

For the six months ended June 30, 2013, the loss in operating revenues from economic hedge positions was driven by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period and offset by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain in operating costs and expenses from economic hedge positions was primarily driven by the reversal of previously recognized unrealized losses from fuel contracts that settled during the period. 

For the six months ended June 30, 2012, the gain in operating revenues from economic hedge positions was driven by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain was partially offset by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period. The loss in operating costs and expenses from economic hedge positions was driven by decrease in the value of forward purchases of fuel contracts, primarily as a result of decreases in forward coal prices. The loss was partially offset by the reversal of previously recognized unrealized losses from fuel contracts that settled during the period.

In accordance with ASC 815, the following table represents the results of GenOn Americas Generation's financial and physical trading of energy commodities. The realized and unrealized financial and physical trading results are included in other operating revenues. GenOn Americas Generation's trading activities are subject to limits within the risk management policy.

	Successor		Predecessors		Successor		Predecessors
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Trading gains/(losses)
Realized	$	2	$	—	$	2	$	(5	)
Unrealized	1		11		—		4
Total trading gains/(losses)	$	3	$	11	$	2	$	(1	)

Other Cost of Operations

Other cost of operations increased by $17 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Reversal of liability for Potomac River in connection with its deactivation	$	31
Decrease due to the revaluation of operating lease liabilities in acquisition accounting in December 2012	(12		)
Other	(2		)
	$	17

Other cost of operations decreased by $1 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Reversal of liability for Potomac River in connection with its deactivation	$	31
Decrease due to the revaluation of operating lease liabilities in acquisition accounting in December 2012	(24		)
Decrease in other costs primarily related to timing of maintenance and outage work	(6		)
	$	1

Depreciation and Amortization

Depreciation and amortization expense decreased by $21 million and $40 million for the three and six months ended June 30, 2013, respectively, compared to the same period in 2012, which reflects the revaluation of the property, plant and equipment recorded in acquisition accounting in December 2012.

50

GenOn Mid-Atlantic

The following table provides selected financial information for GenOn Mid-Atlantic:

	Successor			Predecessor					Successor			Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013			Three months ended June 30, 2012			Change %		Six months ended June 30, 2013			Six months ended June 30, 2012			Change %
Operating Revenues
Energy revenue (a)	$	180		$	222		(19	)%	$	372		$	425		(12	)%
Capacity revenue (a)	67			49			37		121			95			27
Mark-to-market for economic hedging activities	(4		)	(66		)	94		(152		)	1			N/M
Other revenues	—			3			(100	)	—			7			(100	)
Total operating revenues	243			208			17		341			528			(35	)
Operating Costs and Expenses
Generation cost of sales (a)	82			106			(23	)	159			196			(19	)
Mark-to-market for economic hedging activities	(14		)	47			(130	)	(30		)	72			(142	)
Other cost of operations	79			63			25		156			154			1
Total cost of operations	147			216			(32	)	285			422			(32	)
Depreciation and amortization	14			30			(53	)	30			59			(49	)
Selling, general and administrative — affiliate	17			18			(6	)	33			30			10
Total operating costs and expenses	178			264			(33	)	348			511			(32	)
Operating Income/(Loss)	65			(56		)	216		(7		)	17			(141	)
Other Expense
Interest expense	(1		)	(2		)	(50	)	(2		)	(3		)	(33	)
Total other expense	(1		)	(2		)	(50	)	(2		)	(3		)	(33	)
Income/(Loss) Before Income Taxes	64			(58		)	210		(9		)	14			(164	)
Income taxes	—			—			N/M		—			—			N/M
Net Income/(Loss)	$	64		$	(58	)	210		$	(9	)	$	14		(164	)
Business Metrics
Average natural gas price — Henry Hub ($/MMBtu)	$	4.09		$	2.22		84	%	$	3.71		$	2.48		50	%
MWh sold (in thousands)	1,690			2,785					3,596			4,251
MWh generated (in thousands)	1,690			2,785					3,596			4,251

(a)    Includes realized gains and losses from financially settled transactions.

N/M - Not meaningful

51

Generation Gross Margin

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Energy revenue	$	180	$	222	$	372	$	425
Capacity revenue	67		49		121		95
Other revenues	—		3		—		7
Generation revenue	247		274		493		527
Generation cost of sales	82		106		159		196
Generation gross margin	$	165	$	168	$	334	$	331

Generation gross margin decreased by $3 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Lower gross margin due to a 39% decrease in generation resulting from the deactivation of Potomac River and outages at Chalk Point, partially offset by a 40% increase in average realized prices	$	(18	)
Higher capacity revenues due primarily to a 29% increase in capacity prices	18
Other	(3		)
	$	(3	)

Generation gross margin increased by $3 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Higher capacity revenues due primarily to a 24% increase in capacity prices	$	27
Lower gross margin due to a 15% decrease in generation resulting from the deactivation of Potomac River and outages at Chalk Point, partially offset by a 10% increase in average realized prices	(16		)
Other	(8		)
	$	3

Mark-to-market for Economic Hedging Activities

Mark-to-market for economic hedging activities includes asset-backed hedges that have not been designated as cash flow hedges. Total net mark-to-market results increased by $123 million and decreased by $51 million for the three and six months ended June 30, 2013, respectively, compared to the same periods in 2012.

The breakdown of gains and losses included in operating revenues and operating costs and expenses are as follows:

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Mark-to-market results in operating revenues
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(87	)	$	(98	)	$	(176	)	$	(219	)
Net unrealized gains on open positions related to economic hedges	83			32			24			220
Total mark-to-market (losses)/gains in operating revenues	(4		)	(66		)	(152		)	1
Mark-to-market results in operating costs and expenses
Reversal of previously recognized unrealized losses on settled positions related to economic hedges	11			25			26			44
Net unrealized gains/(losses) on open positions related to economic hedges	3			(72		)	4			(116		)
Total mark-to-market gains/(losses) in operating costs and expenses	$	14		$	(47	)	$	30		$	(72	)

Mark-to-market results consist of unrealized gains and losses. The settlement of these transactions is reflected in the same caption as the items being hedged.

52

For the six months ended June 30, 2013, the loss in operating revenues from economic hedge positions was driven by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period partially offset by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain in operating costs and expenses from economic hedge positions was primarily driven by the reversal of previously recognized unrealized losses from fuel contracts that settled during the period. 

For the six months ended June 30, 2012, the gain in operating revenues from economic hedge positions was driven by an increase in the value of forward sales of electricity and natural gas contracts as a result of decreases in forward power and natural gas prices. The gain was partially offset by the reversal of previously recognized unrealized gains from electricity and natural gas contracts that settled during the period. The loss in operating costs and expenses from economic hedge positions was driven by decrease in the value of forward purchases of fuel contracts, primarily as a result of decreases in forward coal prices.

Other Cost of Operations

Other cost of operations increased by $16 million for the three months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Reversal of liability for Potomac River in connection with its deactivation	$	31
Decrease due to the revaluation of operating lease liabilities in acquisition accounting in December 2012	(12		)
Decrease in other costs primarily related to timing of maintenance and outage work	(3		)
	$	16

Other cost of operations increased by $2 million for the six months ended June 30, 2013, compared to the same period in 2012 due to:

	(In millions)
Reversal of liability for Potomac River in connection with its deactivation	$	31
Decrease due to the revaluation of operating lease liabilities in acquisition accounting in December 2012	(24		)
Other	(5		)
	$	2

Depreciation and Amortization

Depreciation and amortization expense decreased by $16 million and $29 million for the three and six months ended June 30, 2013, respectively, compared to the same period in 2012, which reflects the revaluation of the property, plant and equipment recorded in acquisition accounting in December 2012.

53

ITEM 3 — QUANTATITATIVE AND QUALITATIVE DISLCOSURES ABOUT MARKET RISK (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Item 3 has been omitted from this report pursuant to the reduced disclosure format permitted by General Instruction H(2) to Form 10-Q.

ITEM 4 — CONTROLS AND PROCEDURES (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Conclusion Regarding the Effectiveness of Disclosure Controls and Procedures

Under the supervision and with the participation of the Registrants’ management, including the principal executive officer, principal financial officer and principal accounting officer, the Registrants conducted an evaluation of the effectiveness of the design and operation of disclosure controls and procedures, as such term is defined in Rules 13a-15(e) or 15d-15(e) of the Exchange Act. Based on this evaluation, the Registrants’ principal executive officer, principal financial officer and principal accounting officer concluded that the disclosure controls and procedures were effective as of the end of the period covered by this report on Form 10-Q.

Changes in Internal Control over Financial Reporting

The Registrants continue to integrate certain business operations, information systems, processes and related internal control over financial reporting as a result of the NRG Merger. The Registrants will continue to assess the effectiveness of internal control over financial reporting as merger integration activities continue.

54

PART II

OTHER INFORMATION

Item 1 — LEGAL PROCEEDINGS (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

For a discussion of material legal proceedings in which the Registrants were involved through June 30, 2013, see Note 10, Commitments and Contingencies, to this Form 10-Q.

Item 1A — RISK FACTORS (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Information regarding risk factors appears in Part I, Item 1A, Risk Factors, in the Registrants' 2012 Form 10-K.

Item 2 — UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Item 2 has been omitted from this report for the Registrants pursuant to the reduced disclosure format permitted by General Instruction H(2) to Form 10-Q.

Item 3 — DEFAULTS UPON SENIOR SECURITIES (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Item 3 has been omitted from this report for the Registrants pursuant to the reduced disclosure format permitted by General Instruction H(2) to Form 10-Q.

Item 4 — MINE SAFETY DISCLOSURES (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Not applicable.

Item 5 — OTHER INFORMATION(GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

None.

55

Item 6 — EXHIBITS(GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn Energy, Inc. Exhibit Index

Number	Description	Method of Filing
31.1A1	Rule 13a-14(a)/15d-14(a) certification of David W. Crane	Filed herewith
31.2A1	Rule 13a-14(a)/15d-14(a) certification of Kirkland B. Andrews	Filed herewith
31.3A1	Rule 13a-14(a)/15d-14(a) certification of Ronald B. Stark	Filed herewith
32.A1	Section 1350 Certification	Filed herewith
101 INS	XBRL Instance Document	Filed herewith
101 SCH	XBRL Taxonomy Extension Schema	Filed herewith
101 CAL	XBRL Taxonomy Extension Calculation Linkbase	Filed herewith
101 DEF	XBRL Taxonomy Extension Definition Linkbase	Filed herewith
101 LAB	XBRL Taxonomy Extension Label Linkbase	Filed herewith
101 PRE	XBRL Taxonomy Extension Presentation Linkbase	Filed herewith

GenOn Americas Generation, LLC Exhibit Index

Number	Description	Method of Filing
31.1A2	Rule 13a-14(a)/15d-14(a) certification of David W. Crane	Filed herewith
31.2A2	Rule 13a-14(a)/15d-14(a) certification of Kirkland B. Andrews	Filed herewith
31.3A2	Rule 13a-14(a)/15d-14(a) certification of Ronald B. Stark	Filed herewith
32.A2	Section 1350 Certification	Filed herewith
101 INS	XBRL Instance Document	Filed herewith
101 SCH	XBRL Taxonomy Extension Schema	Filed herewith
101 CAL	XBRL Taxonomy Extension Calculation Linkbase	Filed herewith
101 DEF	XBRL Taxonomy Extension Definition Linkbase	Filed herewith
101 LAB	XBRL Taxonomy Extension Label Linkbase	Filed herewith
101 PRE	XBRL Taxonomy Extension Presentation Linkbase	Filed herewith

GenOn Mid-Atlantic, LLC Exhibit Index

Number	Description	Method of Filing
31.1A3	Rule 13a-14(a)/15d-14(a) certification of David W. Crane	Filed herewith
31.2A3	Rule 13a-14(a)/15d-14(a) certification of Kirkland B. Andrews	Filed herewith
31.3A3	Rule 13a-14(a)/15d-14(a) certification of Ronald B. Stark	Filed herewith
32.A3	Section 1350 Certification	Filed herewith
101 INS	XBRL Instance Document	Filed herewith
101 SCH	XBRL Taxonomy Extension Schema	Filed herewith
101 CAL	XBRL Taxonomy Extension Calculation Linkbase	Filed herewith
101 DEF	XBRL Taxonomy Extension Definition Linkbase	Filed herewith
101 LAB	XBRL Taxonomy Extension Label Linkbase	Filed herewith
101 PRE	XBRL Taxonomy Extension Presentation Linkbase	Filed herewith

56

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

GENON ENERGY, INC. (Registrant)
	/s/ DAVID W. CRANE
	David W. Crane Chief Executive Officer
	(Principal Executive Officer)
	/s/ KIRKLAND B. ANDREWS
	Kirkland B. Andrews Chief Financial Officer
	(Principal Financial Officer)
	/s/ RONALD B. STARK
	Ronald B. Stark Chief Accounting Officer
	(Principal Accounting Officer)

Date: August 9, 2013

57

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

GENON AMERICAS GENERATION, LLC (Registrant)
	/s/ DAVID W. CRANE
	David W. Crane Chief Executive Officer
	(Principal Executive Officer)
	/s/ KIRKLAND B. ANDREWS
	Kirkland B. Andrews Chief Financial Officer
	(Principal Financial Officer)
	/s/ RONALD B. STARK
	Ronald B. Stark Chief Accounting Officer
	(Principal Accounting Officer)

Date: August 9, 2013

58

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

GENON MID-ATLANTIC, LLC (Registrant)
	/s/ DAVID W. CRANE
	David W. Crane Chief Executive Officer
	(Principal Executive Officer)
	/s/ KIRKLAND B. ANDREWS
	Kirkland B. Andrews Chief Financial Officer
	(Principal Financial Officer)
	/s/ RONALD B. STARK
	Ronald B. Stark Chief Accounting Officer
	(Principal Accounting Officer)

Date: August 9, 2013

59

EX-31.1A1

EXHIBIT 31.1 A1

CERTIFICATION

I, David W. Crane, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Energy, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ DAVID W. CRANE

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

Date: August 9, 2013

EX-31.1A2

EXHIBIT 31.1 A2

CERTIFICATION

I, David W. Crane, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Americas Generation, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ DAVID W. CRANE

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

Date: August 9, 2013

EX-31.1A3

EXHIBIT 31.1 A3

CERTIFICATION

I, David W. Crane, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Mid-Atlantic, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ DAVID W. CRANE

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

Date: August 9, 2013

EX-31.2A1

EXHIBIT 31.2 A1

CERTIFICATION

I, Kirkland B. Andrews, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Energy, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

Date: August 9, 2013

EX-31.2A2

EXHIBIT 31.2 A2

CERTIFICATION

I, Kirkland B. Andrews, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Americas Generation, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

Date: August 9, 2013

EX-31.2A3

EXHIBIT 31.2 A3

CERTIFICATION

I, Kirkland B. Andrews, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Mid-Atlantic, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

Date: August 9, 2013

EX-31.3A1

EXHIBIT 31.3 A1

CERTIFICATION

I, Ronald B. Stark, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Energy, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ RONALD B. STARK

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer)

Date: August 9, 2013

EX-31.3A2

EXHIBIT 31.3 A2

CERTIFICATION

I, Ronald B. Stark, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Americas Generation, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ RONALD B. STARK

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer)

Date: August 9, 2013

EX-31.3A3

EXHIBIT 31.3 A3

CERTIFICATION

I, Ronald B. Stark, certify that:

1. I have reviewed this quarterly report on Form 10-Q of GenOn Mid-Atlantic, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

/s/ RONALD B. STARK

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer)

Date: August 9, 2013

EX-32.A1

EXHIBIT 32.A1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of GenOn Energy, Inc. on Form 10-Q for the quarter ended June 30, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Form 10-Q”), each of the undersigned officers of the Company certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer's knowledge:

(1) The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Form 10-Q.

Date: August 9, 2013

/s/ DAVID W. CRANE  

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

/s/ RONALD B. STARK  

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer) 

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of this Form 10-Q or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to GenOn Energy, Inc. and will be retained by GenOn Energy, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

EX-32.A2

EXHIBIT 32.A2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of GenOn Americas Generation, LLC on Form 10-Q for the quarter ended June 30, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Form 10-Q”), each of the undersigned officers of the Company certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer's knowledge:

(1) The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Form 10-Q.

Date: August 9, 2013

/s/ DAVID W. CRANE  

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

/s/ RONALD B. STARK  

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer) 

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of this Form 10-Q or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to GenOn Americas Generation, LLC and will be retained by GenOn Americas Generation, LLC and furnished to the Securities and Exchange Commission or its staff upon request.

EX-32.A3

EXHIBIT 32.A3

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of GenOn Mid-Atlantic, LLC on Form 10-Q for the quarter ended June 30, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Form 10-Q”), each of the undersigned officers of the Company certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer's knowledge:

(1) The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Form 10-Q.

Date: August 9, 2013

/s/ DAVID W. CRANE  

David W. Crane

Chief Executive Officer

(Principal Executive Officer)

/s/ KIRKLAND B. ANDREWS

Kirkland B. Andrews

Chief Financial Officer

(Principal Financial Officer)

/s/ RONALD B. STARK  

Ronald B. Stark

Chief Accounting Officer

(Principal Accounting Officer) 

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of this Form 10-Q or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to GenOn Mid-Atlantic, LLC and will be retained by GenOn Mid-Atlantic, LLC and furnished to the Securities and Exchange Commission or its staff upon request.

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2013

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Contingencies

Set forth below is a description of the Registrants’ material legal proceedings. The Registrants believe that they have valid defenses to these legal proceedings and intend to defend them vigorously. The Registrants record reserves for estimated losses from contingencies when information available indicates that a loss is probable and the amount of the loss, or range of loss, can be reasonably estimated. In addition, legal costs are expensed as incurred. Management has assessed each of the following matters based on current information and made a judgment concerning its potential outcome, considering the nature of the claim, the amount and nature of damages sought, and the probability of success. Unless specified below, the Registrants are unable to predict the outcome of these legal proceedings or reasonably estimate the scope or amount of any associated costs and potential liabilities. As additional information becomes available, management adjusts its assessment and estimates of such contingencies accordingly. Because litigation is subject to inherent uncertainties and unfavorable rulings or developments, it is possible that the ultimate resolution of the Registrants’ liabilities and contingencies could be at amounts that are different from currently recorded reserves and that such difference could be material.

In addition to the legal proceedings noted below, the Registrants are parties to other litigation or legal proceedings arising in the ordinary course of business. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect the Registrants’ respective consolidated financial position, results of operations, or cash flows.

Global Warming (GenOn)

In February 2008, the Native Village of Kivalina and the City of Kivalina, Alaska filed a suit in the U.S. District Court for the Northern District of California against GenOn and 23 other electric generating and oil and gas companies. The lawsuit sought damages of up to $400 million for the cost of relocating the village allegedly because of global warming caused by the greenhouse gas emissions of the defendants. In late 2009, the District Court ordered that the case be dismissed and the plaintiffs appealed. In September 2012, the U.S. Court of Appeals for the Ninth Circuit dismissed plaintiffs’ appeal. In October 2012, the plaintiffs petitioned for en banc rehearing of the case; which petition was denied in November 2012. In February 2013, plaintiffs filed a petition with the U.S. Supreme Court seeking review of the decision from the U.S. Court of Appeals. On May 20, 2013, the U.S. Supreme Court denied plaintiffs petition, thereby ending the case.

Actions Pursued by MC Asset Recovery (GenOn)

With Mirant Corporation's emergence from bankruptcy protection in 2006, certain actions filed by GenOn Energy Holdings and some of its subsidiaries against third parties were transferred to MC Asset Recovery, a wholly owned subsidiary of GenOn Energy Holdings.  MC Asset Recovery is governed by a manager who is independent of NRG and GenOn.  MC Asset Recovery is a disregarded entity for income tax purposes.

Under one of the remaining actions transferred to MC Asset Recovery, MC Asset Recovery seeks to recover damages from Commerzbank AG and various other banks, or the Commerzbank Defendants, for alleged fraudulent transfers that occurred prior to GenOn Energy Holdings' bankruptcy proceedings.  In December 2010, the United States District Court for the Northern District of Texas dismissed MC Asset Recovery's complaint against the Commerzbank Defendants.  In January 2011, MC Asset Recovery appealed the United States District Court's dismissal of its complaint against the Commerzbank Defendants to the United States Court of Appeals for the Fifth Circuit.  In March 2012, the United States Court of Appeals for the Fifth Circuit reversed the United States District Court's dismissal and reinstated MC Asset Recovery's amended complaint against the Commerzbank Defendants.  If MC Asset Recovery succeeds in obtaining any recoveries from the Commerzbank Defendants, the Commerzbank Defendants have asserted that they will seek to file claims in GenOn Energy Holdings' bankruptcy proceedings for the amount of those recoveries.  GenOn Energy Holdings would vigorously contest the allowance of any such claims. If the Commerzbank Defendants were to receive an allowed claim as a result of a recovery by MC Asset Recovery on its claims against them, GenOn Energy Holdings would retain from the net amount recovered by MC Asset Recovery an amount equal to the dollar amount of the resulting allowed claim.

Pending Natural Gas Litigation (GenOn)

GenOn is party to five lawsuits, several of which are class action lawsuits, in state and federal courts in Kansas, Missouri, Nevada and Wisconsin. These lawsuits were filed in the aftermath of the California energy crisis in 2000 and 2001 and the resulting FERC investigations and relate to alleged conduct to increase natural gas prices in violation of antitrust and similar laws. The lawsuits seek treble or punitive damages, restitution and/or expenses. The lawsuits also name as parties a number of energy companies unaffiliated with GenOn. In July 2011, the U.S. District Court for the District of Nevada, which is handling four of the five cases, granted the defendants’ motion for summary judgment and dismissed all claims against GenOn in those cases. The plaintiffs appealed to the U.S. Court of Appeals for the Ninth Circuit. The Ninth Circuit reversed the decision of the U.S. District Court for the District of Nevada. In September 2012, the State of Nevada Supreme Court, which is handling the remaining case, affirmed dismissal by the Eighth Judicial District Court for Clark County, Nevada of all plaintiffs’ claims against GenOn. In February 2013, the plaintiffs filed a petition for certiorari to the U.S. Supreme Court. On June 24, 2013, the U.S. Supreme Court denied the petition for certiorari, thereby ending one of the five lawsuits. GenOn has agreed to indemnify CenterPoint against certain losses relating to these lawsuits.

New Source Review Matters

The EPA and various states are investigating compliance of coal-fueled electric generating facilities with the pre-construction permitting requirements of the CAA known as “new source review.” Since 2000, the EPA has made information requests concerning the Avon Lake, Chalk Point, Cheswick, Conemaugh, Dickerson, Elrama, Keystone, Morgantown, New Castle, Niles, Portland, Potomac River, Shawville and Titus generating facilities. The Registrants continue to correspond with the EPA regarding some of these requests. The EPA agreed to share information relating to its investigations with state environmental agencies. In January 2009, GenOn received an NOV from the EPA alleging that past work at its Shawville, Portland and Keystone generating facilities violated regulations regarding new source review. In June 2011, GenOn received an NOV from the EPA alleging that past work at the Niles and Avon Lake generating facilities violated regulations regarding new source review.

In December 2007, the NJDEP sued GenOn in the U.S. District Court for the Eastern District of Pennsylvania, alleging that new source review violations occurred at the Portland generating facility. The suit sought installation of “best available” control technologies for each pollutant, to enjoin GenOn from operating the generating facility if it is not in compliance with the CAA and civil penalties. The suit also named past owners of the plant as defendants, but the claims against the past owners have since been dismissed. In March 2009, the Connecticut Department of Energy and Environmental Protection became an intervening party to the suit. GenOn believes that the work listed by the EPA and the work subject to the NJDEP suit were conducted in compliance with applicable regulations. The parties appeared for mediation before the magistrate judge on April 10, 2013. The parties reached a settlement in principle of this matter on that date. On May 15, 2013, the parties submitted an agreed upon proposed Consent Decree to the court. No objections to the proposed Consent Decree were filed. On July 18, 2013, the court entered the Consent Decree resolving the matter.

In addition, the NJDEP filed two administrative petitions with the EPA in 2010 alleging that the Portland generating facility’s emissions were significantly contributing to nonattainment and/or interfering with the maintenance of certain NAAQS in New Jersey. In November 2011, the EPA published a final rule in response to one of the petitions that required GenOn to reduce maximum allowable SO₂ emissions from the two coal-fired units by about 60% starting in January 2013. In January 2012, GenOn challenged the rule in the U.S. Court of Appeals for the Third Circuit. On July 12, 2013, the Third Circuit denied GenOn's petition seeking review. GenOn has several compliance options until June 1, 2014 that include using lower sulfur coals (although this may at times reduce how much GenOn is able to generate) or running just one unit at a time.

Cheswick Class Action Complaint (GenOn)

In April 2012, a putative class action lawsuit was filed against GenOn in the Court of Common Pleas of Allegheny County, Pennsylvania alleging that emissions from the Cheswick generating facility have damaged the property of neighboring residents.  GenOn disputes these allegations.  Plaintiffs have brought nuisance, negligence, trespass and strict liability claims seeking both damages and injunctive relief.  Plaintiffs seek to certify a class that consists of people who own property or live within one mile of the plant. In July 2012, GenOn removed the lawsuit to the U.S. District Court for the Western District of Pennsylvania. In October 2012, the court granted GenOn’s motion to dismiss, which Plaintiffs have appealed to the U.S. Court of Appeals for the Third Circuit. The Third Circuit heard oral argument on June 25, 2013.

Cheswick Monarch Mine NOV(GenOn)

In 2008, the PADEP issued an NOV related to the Monarch mine located near the Cheswick generating facility. It has not been mined for many years. GenOn uses it for disposal of low-volume wastewater from the Cheswick generating facility and for disposal of leachate collected from ash disposal facilities. The NOV addresses the alleged requirement to maintain a minimum pumping volume from the mine. The PADEP indicated it may assess a civil penalty in excess of $100,000. GenOn contests the allegations in the NOV and has not agreed to such penalty. GenOn is currently planning capital expenditures in connection with wastewater from Cheswick and leachate from ash disposal facilities.

Ormond Beach Alleged Federal Clean Water Act Violations (GenOn)

In October 2012, the Wishtoyo Foundation, a California-based cultural and environmental advocacy organization, through its Ventura Coastkeeper Program, filed suit in the U.S. District Court for the Central District of California regarding alleged violations of the Clean Water Act associated with discharges of stormwater from the Ormond Beach generating facility. The Wishtoyo Foundation alleges that elevated concentrations of pollutants in stormwater discharged from the Ormond Beach generating facility were affecting adjacent aquatic resources in violation of (i) the Statewide General Industrial Stormwater permit (a general National Pollution Discharge Elimination System permit issued by the California State Water Resources Control Board that authorizes stormwater discharges from industrial facilities in California) and (ii) the state’s Porter-Cologne Water Quality Control Act. The Wishtoyo Foundation further alleged that GenOn had not implemented effective stormwater control and treatment measures and that GenOn had not complied with the sampling and reporting requirements of the General Industrial Stormwater permit. GenOn settled this matter in May 2013 and agreed to make operational changes and pay $79,000 in legal fees, $65,000 for supplemental environmental projects and $15,000 for monitoring costs.

Maryland Fly Ash Facilities

GenOn MD Ash Management has three fly ash facilities in Maryland: Faulkner, Westland and Brandywine. GenOn MD Ash Management disposes of fly ash from the Morgantown and Chalk Point generating facilities at Brandywine. GenOn MD Ash Management disposes of fly ash from the Dickerson generating facility at Westland. GenOn MD Ash Management no longer disposes of fly ash at the Faulkner facility. As described below, the MDE had sued GenOn MD Ash Management and GenOn Mid-Atlantic regarding Faulkner, Brandywine and Westland. The MDE also had threatened not to renew the water discharge permits for all three facilities.

Faulkner Litigation. In May 2008, the MDE sued GenOn Mid-Atlantic and GenOn MD Ash Management in the Circuit Court for Charles County, Maryland alleging violations of Maryland’s water pollution laws at Faulkner. The MDE contended that the operation of Faulkner had resulted in the discharge of pollutants that exceeded Maryland’s water quality criteria and without the appropriate NPDES permit. The MDE also alleged that GenOn failed to perform certain sampling and reporting required under an applicable NPDES permit. The MDE complaint requested that the court (i) prohibit continuation of the alleged unpermitted discharges, (ii) require GenOn to cease from further disposal of any coal combustion byproducts at Faulkner and close and cap the existing disposal cells and (iii) assess civil penalties. In July 2008, GenOn filed a motion to dismiss the complaint, arguing that the discharges are permitted by a December 2000 Consent Order. In January 2011, the MDE dismissed without prejudice its complaint and informed GenOn that it intended to file a similar lawsuit in federal court. In May 2011, the MDE filed a complaint against GenOn Mid-Atlantic and GenOn MD Ash Management in the U.S. District Court for the District of Maryland alleging violations at Faulkner of the Clean Water Act and Maryland’s Water Pollution Control Law. The MDE contends that (i) certain of GenOn's water discharges are not authorized by the existing permit and (ii) operation of the Faulkner facility has resulted in discharges of pollutants that violate water quality criteria. The complaint asked the court to, among other things, (i) enjoin further disposal of coal ash; (ii) enjoin discharges that are not authorized by the existing permit; (iii) require numerous technical studies; (iv) impose civil penalties and (v) award MDE attorneys’ fees. GenOn disputed these allegations.

Brandywine Litigation. In April 2010, the MDE filed a complaint against GenOn Mid-Atlantic and GenOn MD Ash Management in the U.S. District Court for the District of Maryland asserting violations at Brandywine of the Clean Water Act and Maryland’s Water Pollution Control Law. The MDE contended that the operation of Brandywine has resulted in discharges of pollutants that violate Maryland’s water quality criteria. The complaint requested that the court, among other things, (i) enjoin further disposal of coal combustion waste at Brandywine, (ii) require GenOn to close and cap the existing open disposal cells within one year, (iii) impose civil penalties and (iv) award MDE attorneys’ fees. GenOn disputed the allegations. In September 2010, four environmental advocacy groups became intervening parties in the proceeding.

Westland Litigation. In January 2011, the MDE informed GenOn that it intended to sue for alleged violations at Westland of Maryland’s water pollution laws, which suit was filed in the U.S. District Court for the District of Maryland in December 2012.

Permit Renewals. In March 2011, the MDE tentatively determined to deny GenOn MD Ash Management's application for the renewal of the water discharge permit for Brandywine, which could result in a significant increase in operating expenses for the Chalk Point and Morgantown generating facilities. The MDE also had indicated that it was planning to deny GenOn’s applications for the renewal of the water discharge permits for Faulkner and Westland. Denial of the renewal of the water discharge permit for the latter facility could have resulted in a significant increase in operating expenses for GenOn Mid-Atlantic's Dickerson generating facility.

Settlement. In June 2011, the MDE agreed to stay the litigation related to Faulkner and Brandywine while GenOn pursued settlement of allegations related to the three Maryland ash facilities. MDE also agreed not to pursue its tentative denial of GenOn’s application to renew the water discharge permit at Brandywine and agreed not to act on GenOn’s renewal applications for Faulkner or Westland while GenOn was discussing settlement. As a condition to obtaining the stay, GenOn agreed in principle to pay a civil penalty of $1.9 million (for alleged past violations) to the MDE if GenOn reached a comprehensive settlement regarding all of the allegations related to the three Maryland ash facilities. GenOn accrued $1.9 million during 2011 and an additional $0.6 million (for agreed prospective penalties while GenOn implements the settlement) during the second quarter of 2012 for a total of $2.5 million. GenOn also developed a technical solution, which includes installing synthetic caps on the closed cells of each of the three ash facilities. During 2011, GenOn accrued $47 million for the estimated cost of the technical solution. At this time, GenOn cannot reasonably estimate the upper range of its obligations for remediating the sites because GenOn has not (i) finished assessing each site including identifying the full impacts to both ground and surface water and the impacts to the surrounding habitat; (ii) finalized with the MDE the standards to which it must remediate; and (iii) identified the technologies required, if any, to meet the yet to be determined remediation standards at each site nor the timing of the design and installation of such technologies. A hearing was held on March 18, 2013 on entry of the Consent Decree. In April2013, GenOn MD Ash Management and MDE signed a slightly revised consent decree, which was approved by the court on April 30, 2013. Accordingly, these issues have been resolved.

Purported Class Actions related to July 22, 2012 Announcement of NRG Merger Agreement (GenOn)

GenOn was named as a defendant in eight purported class actions in Texas and Delaware, related to its announcement of its agreement for NRG to acquire all outstanding shares of GenOn. These cases were consolidated into one state court case in each of Delaware and Texas and a federal court case in Texas. The plaintiffs generally alleged breach of fiduciary duties, as well as conspiracy, aiding and abetting breaches of fiduciary duties. Plaintiffs generally sought to: be certified as a class; enjoin the merger; direct the defendants to exercise their fiduciary duties; rescind the acquisition and be awarded attorneys' fees and costs and other relief that the court deems appropriate. Plaintiffs also demanded that there be additional disclosures regarding the merger terms. On October 24, 2012, the parties to the Delaware state court case executed a Memorandum of Understanding to resolve the Delaware purported class action lawsuit. In March 2013, the parties finalized the settlement of the Delaware action. On June 3, 2013, the court approved the Delaware class action settlement thereby ending the Delaware lawsuit.

Maryland Department of the Environment v. GenOn Chalk Point and GenOn Mid-Atlantic

In January 2013, Food & Water Watch, the Patuxent Riverkeeper and the Potomac Riverkeeper (together, Citizens Group) sent GenOn Mid-Atlantic a letter alleging that the Chalk Point, Dickerson and Morgantown generating facilities were violating the terms of three National Pollution Discharge Elimination System Permits by discharging nitrogen and phosphorous in excess of the limits in each permit. On March 21, 2013 the MDE sent the Company a similar letter with respect to the Chalk Point and Dickerson facilities, threatening to sue within 60 days if the facilities were not brought into compliance. On June 11, 2013, the Maryland Attorney General on behalf of the MDE filed a complaint in the United States District Court for the District of Maryland alleging violations of the Clean Water Act and Maryland environmental laws related to water. The lawsuit seeks injunctive relief and civil penalties.

Chapter 11 Proceedings (GenOn and GenOn Americas Generation)

In July 2003, and various dates thereafter, the Mirant Debtors filed voluntary petitions in the Bankruptcy Court for relief under Chapter 11 of the U.S. Bankruptcy Code. GenOn Energy Holdings and most of the other Mirant Debtors emerged from bankruptcy on January 3, 2006, when the Plan became effective. The remaining Mirant Debtors emerged from bankruptcy on various dates in 2007. Approximately 461,000 of the shares of GenOn Energy Holdings common stock to be distributed under the Plan have not yet been distributed and have been reserved for distribution with respect to claims disputed by the Mirant Debtors that have not been resolved. Upon the Mirant/RRI Merger, those reserved shares converted into a reserve for approximately 1.3 million shares of GenOn common stock. Upon the NRG Merger, those reserved shares converted into a reserve for approximately 159,000 shares of NRG common stock. Under the terms of the Plan, upon the resolution of such a disputed claim, the claimant will receive the same pro rata distributions of common stock, cash, or both as previously allowed claims, regardless of the price at which the common stock is trading at the time the claim is resolved. If the aggregate amount of any such payouts results in the number of reserved shares being insufficient, additional shares of common stock may be issued to address the shortfall.

Texas Franchise Audit (GenOn)

During the second quarter of 2013, GenOn settled the Texas Franchise tax dispute with the state relating to years 2001 through 2007. Prior to NRG Merger, the State of Texas issued franchise tax assessments against GenOn as a result of its audit indicating an underpayment of franchise tax of $72 million (including interest and penalties through June 30, 2013 of $29 million). These assessments relate primarily to a claim by Texas that would change the sourcing of intercompany receipts thereby increasing the amount of tax due. GenOn disagreed with most of the State's assessment and its determination and had accordingly accrued a portion of the liability but had protested the entire assessment.  In June 2013, the Company settled the matter with the State by agreeing to pay $11 million on issues arising from the audit, and reversed the remainder of the accrual. The reversal was recorded as a measurement period adjustment to the amounts recognized on the acquisition date.

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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor
Other comprehensive income/(loss), tax	$ 0	$ 0	$ 0	$ 0

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NRG Merger

6 Months Ended

Jun. 30, 2013

Business Combinations [Abstract]

NRG Merger (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

NRG Merger (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

On December 14, 2012, NRG completed the acquisition of GenOn.  Consideration for the acquisition was valued at $2.2 billion and was comprised of 0.1216 shares of NRG common stock for each outstanding share of GenOn, including restricted stock units outstanding, on the acquisition date, except for fractional shares which were paid in cash. 

The acquisition was recorded as a business combination, with identifiable assets acquired and liabilities assumed provisionally recorded at their estimated fair values on the acquisition date. The initial accounting for the business combination is not complete because the evaluations necessary to assess the fair value of certain net assets acquired is still in process. See Note 3, NRG Merger, in the Registrants' 2012 Form 10-K for additional information related to the NRG Merger.

The following tables summarize the historical carrying amounts, the acquisition accounting adjustments, the preliminary acquisition-date fair value and the measurement period adjustments through June 30, 2013 to the provisional allocation for assets acquired and liabilities assumed initially recorded in 2012 due to the ongoing evaluation of initial estimates. The allocation of the purchase price may be modified up to one year from the date of acquisition as more information is obtained about the fair value of assets acquired and liabilities assumed.

GenOn

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	983	$	—		$	983	$	—		$	983
Other current and non-current assets	2,049		(664		)	1,385		(18		)	1,367
Property, plant and equipment	6,286		(2,350		)	3,936		(27		)	3,909
Derivative assets	1,143		14			1,157		—			1,157
Deferred income taxes	220		—			220		—			220
Total assets	$	10,681	$	(3,000	)	$	7,681	$	(45	)	$	7,636
Liabilities
Other current and non-current liabilities	$	1,299	$	13		1,312		$	10		$	1,322
Out-of-market contracts and leases	331		733			1,064		15			1,079
Derivative liabilities	414		(15		)	399		—			399
Deferred income taxes	220		—			220		—			220
Long-term debt and capital leases	3,725		478			4,203		3			4,206
Total liabilities	$	5,989	$	1,209		$	7,198	$	28		$	7,226
Net assets	$	4,692	$	(4,209	)	$	483	$	(73	)	$	410

GenOn Americas Generation

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	171	$	—		$	171	$	—		$	171
Other current and non-current assets	1,509		(531		)	978		(14		)	964
Property, plant and equipment	2,875		(1,546		)	1,329		(60		)	1,269
Derivative assets	1,226		12			1,238		—			1,238
Total assets	$	5,781	$	(2,065	)	$	3,716	$	(74	)	$	3,642
Liabilities
Other current and non-current liabilities	$	705	$	(34	)	$	671	$	—		$	671
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	539		(10		)	529		—			529
Long-term debt and capital leases	862		99			961		—			961
Total liabilities	$	2,106	$	595		$	2,701	$	15		$	2,716
Net assets	$	3,675	$	(2,660	)	$	1,015	$	(89	)	$	926

GenOn Mid-Atlantic

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	163	$	—		$	163	$	—		$	163
Other current and non-current assets	700		(502		)	198		(12		)	186
Property, plant and equipment	2,399		(1,178		)	1,221		(110		)	1,111
Derivative assets	851		12			863		—			863
Total assets	$	4,113	$	(1,668	)	$	2,445	$	(122	)	$	2,323
Liabilities
Other current and non-current liabilities	$	198	$	6		$	204	—			$	204
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	172		(10		)	162		—			162
Long-term debt and capital leases	14		—			14		—			14
Total liabilities	$	384	$	536		$	920	$	15		$	935
Net assets	$	3,729	$	(2,204	)	$	1,525	$	(137	)	$	1,388

The estimated fair values of the property, plant and equipment were significantly lower than the book value, which reflects changes to expected market dynamics, including commodity prices, resulting in lower estimated cash flows and in some cases, shorter useful lives of the underlying assets. The measurement period adjustments for property, plant and equipment primarily reflect revisions of various estimates based on additional information available. In addition, the difference between the historical tax basis of the assets and liabilities over the net amount assigned to the assets and liabilities in acquisition accounting was recorded as a net deferred tax asset. Based on cumulative pre-tax losses, a valuation allowance for the full amount of the net deferred tax assets was also recorded.

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Income Taxes (Tables)

6 Months Ended

Jun. 30, 2013

Income Tax Disclosure [Abstract]

Income tax (benefit)/provision

GenOn’s income tax (benefit)/expense consisted of the following:

	Successor		Predecessor		Successor		Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Income/(loss) before income taxes	79		(224	)	(154	)	(256	)
Income tax (benefit)/expense	(6	)	4		(6	)	4
Effective tax rate	(7.59	)%	(1.79	)%	3.90	%	(1.56	)%

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Regulatory Matters

6 Months Ended

Jun. 30, 2013

Regulatory Matters Disclosure [Abstract]

Regulatory Matters (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Regulatory Matters (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The Registrants operate in a highly regulated industry and are subject to regulation by various federal and state agencies. As such, the Registrants are affected by regulatory developments at both the federal and state levels and in the regions in which they operate. In addition, the Registrants are subject to the market rules, procedures, and protocols of the various ISO markets in which they participate. These power markets are subject to ongoing legislative and regulatory changes that may impact the Registrants.

In addition to the regulatory proceedings noted below, the Registrants are a party to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect the Registrants’ respective consolidated financial position, results of operations, or cash flows.

East Region (GenOn)

RMR Agreements for Elrama and Niles — In May 2012, GenOn filed with FERC an RMR rate schedule governing operation of unit 4 of the Elrama generating facility and unit 1 of the Niles generating facility.  PJM determined that each of these units was needed past its planned deactivation date of June 1, 2012 to maintain transmission system reliability on the PJM system pending the completion of transmission upgrades.  The RMR rate schedule sets forth the terms, conditions and cost-based rates under which GenOn operated the units for reliability purposes through September 30, 2012, the date PJM indicated the units would no longer be needed for reliability.  In July 2012, FERC accepted GenOn's RMR rate schedule subject to hearing and settlement procedures.  In the settlement discussions ordered by FERC, or in any subsequent hearing, GenOn's RMR rate schedule may be modified from that which was filed.  The rates GenOn charged are subject to refund pending a ruling or settlement. GenOn filed a settlement of all outstanding issues in May 2013, which several parties are contesting. Any eventual settlement must be approved by FERC.

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Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended							1 Months Ended
	Jun. 30, 2013 GenOn Americas Generation GenOn Energy Holdings	Dec. 31, 2012 GenOn Americas Generation GenOn Energy Holdings	Jun. 30, 2013 Successor NRG Energy	Jun. 30, 2013 Successor NRG Energy	Jun. 30, 2013 Successor GenOn Americas Generation GenOn Energy Management	Jun. 30, 2013 Successor GenOn Americas Generation GenOn Energy Management	Jun. 30, 2013 Successor GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor GenOn Mid-Atlantic GenOn Energy Management	Jun. 30, 2013 Successor GenOn Mid-Atlantic GenOn Energy Management	Jun. 30, 2013 Successor GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Direct cost of operations GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Direct cost of operations GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Direct cost of operations GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Direct cost of operations GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Allocated cost of operations GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Allocated cost of operations GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Allocated cost of operations GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Allocated cost of operations GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Allocated selling, general and administrative GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Allocated selling, general and administrative GenOn Americas Generation NRG Energy	Jun. 30, 2013 Successor Allocated selling, general and administrative GenOn Mid-Atlantic NRG Energy	Jun. 30, 2013 Successor Allocated selling, general and administrative GenOn Mid-Atlantic NRG Energy	Jun. 30, 2012 Predecessor GenOn Americas Generation GenOn Energy Management	Jun. 30, 2012 Predecessor GenOn Americas Generation GenOn Energy Management	Jun. 30, 2012 Predecessor GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic GenOn Energy Management	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic GenOn Energy Management	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Direct cost of operations GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Direct cost of operations GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Direct cost of operations GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Direct cost of operations GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Allocated cost of operations GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Allocated cost of operations GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Allocated cost of operations GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Allocated cost of operations GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Allocated selling, general and administrative GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Allocated selling, general and administrative GenOn Americas Generation GenOn	Jun. 30, 2012 Predecessor Allocated selling, general and administrative GenOn Mid-Atlantic GenOn	Jun. 30, 2012 Predecessor Allocated selling, general and administrative GenOn Mid-Atlantic GenOn	Jun. 30, 2013 Letter of Credit Intercompany Credit Agreement NRG Energy	Dec. 31, 2012 Letter of Credit Intercompany Credit Agreement NRG Energy	Jun. 30, 2013 Letter of Credit Intercompany Credit Agreement GenOn Americas Generation NRG Energy	Dec. 31, 2012 Letter of Credit Intercompany Credit Agreement GenOn Americas Generation NRG Energy	Jun. 30, 2013 Letter of Credit Intercompany Credit Agreement GenOn Mid-Atlantic NRG Energy	Dec. 31, 2012 Letter of Credit Intercompany Credit Agreement GenOn Mid-Atlantic NRG Energy	Jul. 31, 2013 Subsequent Event	Jul. 22, 2013 Subsequent Event Marsh Landing NRG Yield LLC
Related Party Transaction
Annual fees under services agreement				$ 193
Affiliate cost recorded in selling, general and administrative			14	25																	22	42	17	33																	23	39	18	30
Affiliate cost recorded in cost of operations							58	117			38	80	35	70	21	44	1	5	0	3							69	135			44	84	38	79	24	48	8	17	2	6
Increase (decrease) in energy marketing overhead expense					(2)	(4)				1															(6)	(12)			1	2
Maximum borrowing capacity																																													500
Letters of credit issued and oustanding on behalf of entity by affiliate																																													296	261	108	166	78	113
Term of Facility																																													3 years
Debt instrument, interest rate over variable rate (as a percent)																																													2.50%
Basis points added to interest under LIBOR rate loans (as a percent)																																													3.50%
Current note receivable from affiliate	301	198
Emission allowances purchased and utilized									4	8																			4	7
Sale of Marsh Landing, GenOn to Yield, purchae price																																																				199
Sale of Marsh Landing, GenOn to Yield, acqusition-date net assets																																																				168
Sale of Marsh Landing, GenOn to Yield, GenOn APIC adjustment																																																			$ 31

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NRG Merger (Details) (USD $)			6 Months Ended		6 Months Ended		6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 GenOn	Dec. 14, 2012 GenOn	Jun. 30, 2013 GenOn Americas Generation	Dec. 14, 2012 GenOn Americas Generation	Jun. 30, 2013 GenOn Mid-Atlantic	Dec. 14, 2012 GenOn Mid-Atlantic
NRG Merger
Value of the consideration for the acquisition				$ 2,200,000,000
NRG merger exchange ratio				0.1216
Assets
Cash	248,000,000	825,000,000		983,000,000		171,000,000		163,000,000
Cash, acquisition-date fair value				983,000,000		171,000,000		163,000,000
Other current and non-current assets, historical carrying amount				2,049,000,000		1,509,000,000		700,000,000
Other current and non-current assets, acquisition accounting adjustment				(664,000,000)		(531,000,000)		(502,000,000)
Other current and non-current assets, acquisition-date fair value				1,385,000,000		978,000,000		198,000,000
Other current and non-current assets, measurement period adjustments			(18,000,000)		(14,000,000)		(12,000,000)
Other current and non-current assets, revised acquisition-date fair value				1,367,000,000		964,000,000		186,000,000
Property, plant and equipment, historical carrying amount	3,953,000,000	3,919,000,000		6,286,000,000		2,875,000,000		2,399,000,000
Property, plant and equipment, acquistion accounting adjustment				(2,350,000,000)		(1,546,000,000)		(1,178,000,000)
Property, plant and equipment, acquisition-date fair value				3,936,000,000		1,329,000,000		1,221,000,000
Property, plant and equipment, measurement period adjustments			(27,000,000)		(60,000,000)		(110,000,000)
Property, plant and equipment, revised acquistion-date fair value				3,909,000,000		1,269,000,000		1,111,000,000
Derivative assets, historical carrying amount				1,143,000,000		1,226,000,000		851,000,000
Derivative assets, acquisition accounting adjustment				14,000,000		12,000,000		12,000,000
Derivative assets, acquisition-date fair value				1,157,000,000		1,238,000,000		863,000,000
Deferred income taxes (assets), historical carrying amount				220,000,000
Deferred income taxes (assets), acquisition-date fair value				220,000,000
Total assets, historical carrying amount	6,542,000,000	7,461,000,000		10,681,000,000		5,781,000,000		4,113,000,000
Total assets, acquisition accounting adjustment				(3,000,000,000)		(2,065,000,000)		(1,668,000,000)
Total assets, acquisition-date fair value				7,681,000,000		3,716,000,000		2,445,000,000
Total assets, measurement period adjustments			(45,000,000)		(74,000,000)		(122,000,000)
Total assets, revised acquisition-date fair value				7,636,000,000		3,642,000,000		2,323,000,000
Liabilities
Other current and non-current liabilities, historical carrying amount				1,299,000,000		705,000,000		198,000,000
Other current and non-current liabilities, acquisition accounting adjustment				13,000,000		(34,000,000)		6,000,000
Other current and non-current liabilities, acquisition-date fair value				1,312,000,000		671,000,000		204,000,000
Other current and non-current liabilities, measurement period adjustments			10,000,000
Other current and non-current liabilities, revised acquisition-date fair value				1,322,000,000
Out-of-market contracts and leases, historical carrying amount	1,041,000,000	1,077,000,000		331,000,000
Out of market contracts and leases, acquisition accounting adjustment				733,000,000		540,000,000		540,000,000
Out-of-market contracts and leases, acquisition-date fair value				1,064,000,000		540,000,000		540,000,000
Out-of-market contracts and leases, measurement period adjustments			15,000,000		15,000,000		15,000,000
Out-of-market contracts and leases, revised acquistion-date fair value				1,079,000,000		555,000,000		555,000,000
Derivative liabilities, historical carrying amount				414,000,000		539,000,000		172,000,000
Derivative liabilities, acquisition accounting adjustment				(15,000,000)		(10,000,000)		(10,000,000)
Derivative liabilities, acquisition-date fair value				399,000,000		529,000,000		162,000,000
Deferred income taxes (liabilities), historical carrying amount				220,000,000
Deferred income taxes (liabilities), acquisition-date fair value				220,000,000
Long-term debt and capital leases, historical carrying amount				3,725,000,000		862,000,000		14,000,000
Long-term debt and capital leases, acquisition accounting adjustment				478,000,000		99,000,000
Long-term debt and capital leases, acquisition-date fair value				4,203,000,000		961,000,000		14,000,000
Long-term debt and capital leases, measurement period adjustments			3,000,000
Long-term debt and capital leases, revised acquisition-date fair value				4,206,000,000
Total liabilities, historical carrying amount	6,301,000,000	7,121,000,000		5,989,000,000		2,106,000,000		384,000,000
Total liabilities, acquisition accounting adjustment				1,209,000,000		595,000,000		536,000,000
Total liabilities, acquisition-date fair value				7,198,000,000		2,701,000,000		920,000,000
Total liabilities, measurement period adjustments			28,000,000		15,000,000		15,000,000
Total liabilities, revised acquisition-date fair value				7,226,000,000		2,716,000,000		935,000,000
Net assets
Net assets, historical carrying amount				4,692,000,000		3,675,000,000		3,729,000,000
Net assets, acquisition accounting adjustment				(4,209,000,000)		(2,660,000,000)		(2,204,000,000)
Net assets, acquisition-date fair value				483,000,000		1,015,000,000		1,525,000,000
Net assets, measurement period adjustments			(73,000,000)		(89,000,000)		(137,000,000)
Net assets, revised acquisition-date fair value				$ 410,000,000		$ 926,000,000		$ 1,388,000,000

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Basis of Presentation (Details)	Jun. 30, 2013 MW
Basis of Presentation
Generation capacity (in MW)	21,205
GenOn Americas Generation
Basis of Presentation
Generation capacity (in MW)	7,852
GenOn Mid-Atlantic
Basis of Presentation
Generation capacity (in MW)	4,683

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Accounting for Derivative Instruments and Hedging Activities (Details 3) (USD $) In Millions, unless otherwise specified			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 GenOn Americas Generation	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor Gains (losses) included in operating revenues	Jun. 30, 2013 Successor Gains (losses) included in operating revenues	Jun. 30, 2013 Successor Gains (losses) included in cost of operations	Jun. 30, 2013 Successor Gains (losses) included in cost of operations	Jun. 30, 2013 Successor GenOn Americas Generation	Jun. 30, 2013 Successor GenOn Americas Generation	Jun. 30, 2013 Successor GenOn Americas Generation Gains (losses) included in operating revenues	Jun. 30, 2013 Successor GenOn Americas Generation Gains (losses) included in operating revenues	Jun. 30, 2013 Successor GenOn Americas Generation Gains (losses) included in cost of operations	Jun. 30, 2013 Successor GenOn Americas Generation Gains (losses) included in cost of operations	Jun. 30, 2013 Successor GenOn Mid-Atlantic	Jun. 30, 2013 Successor GenOn Mid-Atlantic	Jun. 30, 2013 Successor GenOn Mid-Atlantic Gains (losses) included in operating revenues	Jun. 30, 2013 Successor GenOn Mid-Atlantic Gains (losses) included in operating revenues	Jun. 30, 2013 Successor GenOn Mid-Atlantic Gains (losses) included in cost of operations	Jun. 30, 2013 Successor GenOn Mid-Atlantic Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor GenOn Americas Generation	Jun. 30, 2012 Predecessor GenOn Americas Generation	Jun. 30, 2012 Predecessor GenOn Americas Generation Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor GenOn Americas Generation Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor GenOn Americas Generation Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor GenOn Americas Generation Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic Gains (losses) included in operating revenues	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic Gains (losses) included in cost of operations	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic Gains (losses) included in cost of operations
Unrealized mark-to-market results
Reversal of previously recognized unrealized losses/(gains) on settled positions related to economic hedges			$ (99)	$ (197)					$ (75)	$ (149)					$ (76)	$ (150)					$ (99)	$ (228)					$ (73)	$ (173)					$ (73)	$ (175)
Net unrealized gains/(losses) on open positions related to economic hedges			161	38					86	26					86	28					(54)	182					(46)	110					(40)	104
Total unrealized mark-to-market gains/(losses) for economic hedging activities			62	(159)					11	(123)											(153)	(46)					(119)	(63)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity			1	(2)					1	(2)											5	2					5	2
Net unrealized gains/(losses) on open positions related to trading activity			0	2					0	2											6	2					6	2
Total unrealized mark-to-market gains/(losses) for trading activity			1	0					1	0											11	4					11	4
Total unrealized gains/(losses)			63	(159)	45	(190)	18	31	12	(123)	(2)	(153)	14	30	10	(122)	(4)	(152)	14	30	(142)	(42)	(102)	41	(40)	(83)	(108)	(59)	(68)	7	(40)	(66)	(113)	(71)	(66)	1	(47)	(72)
Impact of derivative instruments to statement of operations
Total impact to statement of operations			63	(159)	45	(190)	18	31	12	(123)	(2)	(153)	14	30	10	(122)	(4)	(152)	14	30	(142)	(42)	(102)	41	(40)	(83)	(108)	(59)	(68)	7	(40)	(66)	(113)	(71)	(66)	1	(47)	(72)
Credit Risk Related Contingent Features
Collateral required for contracts with adequate assurance clauses in net liability positions	15	15
Collateral required for contracts with credit rating contingent features in net liability position	1	1
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	$ 4

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Environmental Matters (Details) (USD $)	12 Months Ended
	Dec. 31, 2008	Jun. 30, 2013
Environmental Matters Disclosure
Estimated environmental capital expenditures from 2013 through 2017		$ 208,000,000
Minimum Civil Penalties which May Be Assumed	100,000
GenOn Americas Generation
Environmental Matters Disclosure
Estimated environmental capital expenditures from 2013 through 2017		46,000,000
GenOn Mid-Atlantic
Environmental Matters Disclosure
Estimated environmental capital expenditures from 2013 through 2017		$ 4,000,000

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Fair Value of Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Derivative fair value measurements
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	2.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	5.00%
Credit reserve balance	$ (3)		$ (4)
Concentration of credit risk
Counterparty credit exposure	810
Collateral held (cash and letters of credit) against counterparty credit exposure	75
Counterparty credit exposure, net	735
Counterparty credit exposure before collateral expected to roll off by the end of 2014 (as a percent)	88.00%
Net exposure (as a percent)	100.00%	[1]
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)			10.00%
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	495
Investment grade
Concentration of credit risk
Net exposure (as a percent)	98.00%	[1]
Non-rated
Concentration of credit risk
Net exposure (as a percent)	2.00%	[1]
Financial institutions
Concentration of credit risk
Net exposure (as a percent)	60.00%	[1]
Utilities, energy merchants, marketers and other
Concentration of credit risk
Net exposure (as a percent)	20.00%	[1]
ISOs
Concentration of credit risk
Net exposure (as a percent)	19.00%	[1]
Coal
Concentration of credit risk
Net exposure (as a percent)	1.00%	[1]
GenOn Americas Generation
Derivative fair value measurements
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	2.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	4.00%
Credit reserve balance	(3)		(4)
Concentration of credit risk
Counterparty credit exposure	803
Collateral held (cash and letters of credit) against counterparty credit exposure	75
Counterparty credit exposure, net	728
Counterparty credit exposure before collateral expected to roll off by the end of 2014 (as a percent)	88.00%
Net exposure (as a percent)	100.00%	[1]
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)			10.00%
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	494
GenOn Americas Generation | Investment grade
Concentration of credit risk
Net exposure (as a percent)	98.00%	[1]
GenOn Americas Generation | Non-rated
Concentration of credit risk
Net exposure (as a percent)	2.00%	[1]
GenOn Americas Generation | Financial institutions
Concentration of credit risk
Net exposure (as a percent)	61.00%	[1]
GenOn Americas Generation | Utilities, energy merchants, marketers and other
Concentration of credit risk
Net exposure (as a percent)	19.00%	[1]
GenOn Americas Generation | ISOs
Concentration of credit risk
Net exposure (as a percent)	19.00%	[1]
GenOn Americas Generation | Coal
Concentration of credit risk
Net exposure (as a percent)	1.00%	[1]
GenOn Mid-Atlantic
Derivative fair value measurements
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	1.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	2.00%
Credit reserve balance	(5)		(4)
Concentration of credit risk
Counterparty credit exposure	512
Collateral held (cash and letters of credit) against counterparty credit exposure	75
Counterparty credit exposure, net	437
Counterparty credit exposure before collateral expected to roll off by the end of 2014 (as a percent)	89.00%
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)			10.00%
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	$ 407
GenOn Mid-Atlantic | Investment grade
Concentration of credit risk
Net exposure (as a percent)	100.00%	[1]
GenOn Mid-Atlantic | Financial institutions
Concentration of credit risk
Net exposure (as a percent)	100.00%	[1]

[1] Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

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Related Party Transactions (Tables)

6 Months Ended

Jun. 30, 2013

GenOn Americas Generation

Related Party Transaction

Summary of material related-party transactions with affiliates

The following costs were incurred under these arrangements:

GenOn Americas Generation

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	35	$	38	$	70	$	79
Allocated costs:
Cost of operations — affiliate	1		8		5		17
Selling, general and administrative — affiliate	22		23		42		39
Total	$	58	$	69	$	117	$	135

GenOn Mid-Atlantic

Related Party Transaction

Summary of material related-party transactions with affiliates

GenOn Mid-Atlantic

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	21	$	24	$	44	$	48
Allocated costs:
Cost of operations — affiliate	—		2		3		6
Selling, general and administrative — affiliate	17		18		33		30
Total	$	38	$	44	$	80	$	84

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CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Property, plant and equipment, accumulated depreciation	$ 129	$ 9
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	1	1
Common stock, shares issued (in shares)	1	1
Intangible assets, accumulated amortization	18	1
GenOn Americas Generation
Property, plant and equipment, accumulated depreciation	46	4
Intangible assets, accumulated amortization	17	1
GenOn Mid-Atlantic
Property, plant and equipment, accumulated depreciation	$ 34	$ 4

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Basis of Presentation

6 Months Ended

Jun. 30, 2013

Basis of Presentation Disclosure [Abstract]

Basis of Presentation (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Basis of Presentation (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn Energy, Inc., a wholly-owned subsidiary of NRG, is a wholesale power generator engaged in the ownership and operation of power generation facilities, with approximately 21,205 MW of net electric generating capacity located in the U.S.

GenOn Americas Generation is a wholesale power generator with approximately 7,852 MW of net electric generating capacity located, in many cases, near major metropolitan areas. GenOn Americas Generation's electric generating capacity is part of the 21,205 MW of net electric generating capacity of GenOn.

GenOn Mid-Atlantic operates and owns or leases 4,683 MW of net electric generating capacity in the Washington, D.C. and Baltimore areas. GenOn Mid-Atlantic’s electric generating capacity is part of the 7,852 MW of net electric generating capacity of GenOn Americas Generation. GenOn Mid-Atlantic’s generating facilities serve the Eastern PJM markets.

GenOn Americas Generation and GenOn Mid-Atlantic are Delaware limited liability companies and indirect wholly-owned subsidiaries of GenOn. GenOn Mid-Atlantic is a wholly-owned subsidiary of NRG North America and an indirect wholly-owned subsidiary of GenOn Americas Generation.

The Registrants sell power from their generation portfolio, offer capacity or similar products to retail electric providers and others, and provide Ancillary Services to support system reliability.

This is a combined quarterly report of the Registrants for the quarter ended June 30, 2013. The notes to the condensed consolidated financial statements apply to the Registrants as indicated parenthetically next to each corresponding disclosure. The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with the SEC's regulations for interim financial information and with the instructions to Form 10-Q. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The following notes should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the Registrants' financial statements set forth in the 2012 Form 10-K. Interim results are not necessarily indicative of results for a full year.

In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Registrants' consolidated financial positions as of June 30, 2013, and the results of operations, comprehensive loss and cash flows for the three months ended June 30, 2013, and 2012.

NRG Merger, Predecessor and Successor Reporting

On December 14, 2012, NRG completed the acquisition of GenOn with GenOn continuing as a wholly-owned subsidiary of NRG. The NRG Merger is accounted for under the acquisition method of accounting. Fair value adjustments related to the NRG Merger have been pushed down to GenOn, GenOn Americas Generation and GenOn Mid-Atlantic, resulting in certain assets and liabilities of the Registrants being recorded at fair value at December 15, 2012. See Note 3, NRG Merger, for further discussion.

The Registrants’ consolidated statements of operations subsequent to the NRG Merger include amortization expense relating to fair value adjustments and depreciation expense based on the fair value of the Registrants’ property, plant and equipment. In addition, effective with the NRG Merger, the Registrants adopted accounting policies of NRG. Therefore, the Registrants' financial information prior to the NRG Merger is not comparable to its financial information subsequent to the NRG Merger.

As a result of the impact of pushdown accounting, the financial statements and certain note presentations separate the Registrants' presentations into two distinct periods, the period before the consummation of the NRG Merger (labeled predecessor) and the period after that date (labeled successor), to indicate the application of different basis of accounting between the periods presented.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.

Reclassifications

Certain prior-year amounts have been reclassified for comparative purposes. The reclassifications did not affect results from operations or cash flows.

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Fair Value of Financial Instruments

6 Months Ended

Jun. 30, 2013

Fair Value of Financial Instruments Disclosure [Abstract]

Fair Value of Financial Instruments (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Fair Value of Financial Instruments (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

This footnote should be read in conjunction with the complete description under Note 5, Fair Value of Financial Instruments, to the Registrants' 2012 Form 10-K.

For cash and cash equivalents, funds deposited by counterparties (GenOn), accounts receivable, note receivable — affiliate (GenOn Americas Generation), accounts payable, accrued expenses and other current liabilities, restricted cash, and cash collateral paid and received in support of energy risk management activities, the carrying amount approximates fair value because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy.

The estimated carrying amounts and fair values of GenOn and GenOn Americas Generation’s long-term debt, including current portion, are as follows:

GenOn

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	3,649	$	3,545	$	4,185	$	4,195

GenOn Americas Generation

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	942	$	909	$	946	$	953

The fair value of GenOn and GenOn Americas Generation's publicly-traded long-term debt is based on quoted market prices and is classified as Level 1 within the fair value hierarchy. The fair value of GenOn's non publicly-traded long-term debt is estimated using current interest rates for similar instruments with equivalent credit quality and is classified as Level 3 within the fair value hierarchy.

Recurring Fair Value Measurements

Derivative assets and liabilities and trust fund investments are carried at fair market value. Realized and unrealized gains and losses included in earnings that are related to energy derivatives are recorded in operating revenues and cost of operations.

GenOn

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn’s consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	127	$	722	$	17	$	866
Derivative liabilities:
Commodity contracts	$	44	$	169	$	14	$	227
Interest rate contracts	—		33		—		33
Total liabilities	$	44	$	202	$	14	$	260
Other assets (a)	$	44	$	—	$	—	$	44

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	139	$	946	$	31	$	1,116
Derivative liabilities:
Commodity contracts	$	52	$	253	$	14	$	319
Interest rate contracts	—		50		—		50
Total liabilities	$	52	$	303	$	14	$	369
Other assets (a)	$	43	$	—	$	—	$	43

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30,2013 and 2012. The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for derivatives that are recognized at fair value in GenOn’s consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(36	)	$	17		$	(31	)
Total gains/(losses) included in earnings — realized/unrealized	3			(95		)	(16		)	(100		)
Purchases	6			—			2			—
Ending balance	$	3		$	(131	)	$	3		$	(131	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(131	)	$	1		$	(136	)

(a) Consists of derivative assets and liabilities, net.

GenOn Americas Generation

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Americas Generation's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	149	$	784	$	19	$	952
Derivative liabilities:
Commodity contracts	$	103	$	258	$	16	$	377

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	170	$	991	$	31	$	1,192
Derivative liabilities:
Commodity contracts	$	123	$	358	$	14	$	495

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30, 2013 and 2012. The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for GenOn Americas Generation's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(30	)	$	17		$	(32	)
Total gains/(losses) included in earnings — realized/unrealized	3			(83		)	(16		)	(81		)
Purchases	6			—			2			—
Ending balance	$	3		$	(113	)	$	3		$	(113	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(121	)	$	1		$	(120	)

(a)    Consists of derivative assets and liabilities, net.

GenOn Mid-Atlantic

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Mid-Atlantic's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	68	$	609	$	4	$	681
Derivative liabilities:
Commodity contracts	$	20	$	86	$	2	$	108

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	63	$	778	$	8	$	849
Derivative liabilities:
Commodity contracts	$	16	$	138	$	1	$	155

There were no transfers during the three and six months endedJune 30,2013 and 2012 between Levels 1 and 2. Transfers in/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. There were no transfers in/out of Level 3 during the three and six months endedJune 30,2013 and 2012. The following tables reconcile, for the three and six months endedJune 30, 2013 and 2012, the beginning and ending balances for GenOn Mid-Atlantic's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(88	)	$	7		$	(64	)
Total gains/(losses) included in earnings — realized/unrealized	2			(50		)	(7		)	(74		)
Purchases	6			—			2			—
Ending balance	$	2		$	(138	)	$	2		$	(138	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	8		$	(90	)	$	1		$	(115	)

(a) Consists of derivative assets and liabilities, net.

Derivative Fair Value Measurements

A portion of the Registrants' contracts are exchange-traded contracts with readily available quoted market prices. A majority of the Registrants' contracts are non-exchange-traded contracts valued using prices provided by external sources, primarily price quotations available through brokers or over-the-counter and on-line exchanges. For the majority of the Registrants' markets, the Registrants receive quotes from multiple sources. To the extent that the Registrants receive multiple quotes, the Registrants' prices reflect the average of the bid-ask mid-point prices obtained from all sources that the Registrants believe provide the most liquid market for the commodity. If the Registrants receive one quote, then the mid-point of the bid-ask spread for that quote is used. The terms for which such price information is available vary by commodity, region and product. A significant portion of the fair value of the Registrants' derivative portfolio is based on price quotes from brokers in active markets who regularly facilitate those transactions and the Registrants believe such price quotes are executable. The Registrants do not use third party sources that derive price based on proprietary models or market surveys. The remainder of the assets and liabilities represents contracts for which external sources or observable market quotes are not available for the whole term or for certain delivery months. These contracts are valued using various valuation techniques including but not limited to internal models that apply fundamental analysis of the market and corroboration with similar markets. As of June 30, 2013, contracts valued with prices provided by models and other valuation techniques make up 2% of GenOn's derivative assets and 5% of GenOn's derivative liabilities, 2% of GenOn Americas Generation’s derivative assets and 4% of GenOn Americas Generation's derivative liabilities and 1% of GenOn Mid-Atlantic’s derivative assets and 2% of GenOn Mid-Atlantic's derivative liabilities.

The fair value of each contract is discounted using a risk free interest rate. In addition, the Registrants apply a credit reserve to reflect credit risk which is calculated based on published default probabilities. To the extent that the Registrants’ net exposure under a specific master agreement is an asset, the Registrants use the counterparty's default swap rate. If the net exposure under a specific master agreement is a liability, the Registrants use their default swap rate. The credit reserve is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume the Registrants’ liabilities or that a market participant would be willing to pay for the Registrants’ assets. The Registrants' credit reserves were as follows:

	As of June 30, 2013			As of December 31, 2012
	(In millions)
GenOn	$	(3	)	$	(4	)
GenOn Americas Generation	$	(3	)	$	(4	)
GenOn Mid-Atlantic	$	(5	)	$	(4	)

Concentration of Credit Risk

In addition to the credit risk discussion as disclosed in Note 2, Summary of Significant Accounting Policies, to the Registrants' 2012 Form 10-K, the following is a discussion of the concentration of credit risk for the Registrants’ financial instruments. Credit risk relates to the risk of loss resulting from non-performance or non-payment by counterparties pursuant to the terms of their contractual obligations. The Registrants are exposed to counterparty credit risk through various activities including wholesale sales and fuel purchases.

Counterparty Credit Risk

The Registrants monitor and manage counterparty credit risk through credit policies that include: (i) an established credit approval process; (ii) daily monitoring of counterparties' credit limits; (iii) the use of credit mitigation measures such as margin, collateral, prepayment arrangements, or volumetric limits; (iv) the use of payment netting arrangements; and (v) the use of master netting agreements that allow for the netting of positive and negative exposures of various contracts associated with a single counterparty. Risk surrounding counterparty performance and credit could ultimately impact the amount and timing of expected cash flows. The Registrants seek to mitigate counterparty credit risk with a diversified portfolio of counterparties. The Registrants also have credit protection within various agreements to call on additional collateral support if and when necessary. Cash margin is collected and held to cover the credit risk of the counterparty until positions settle.

As of June 30, 2013, GenOn's counterparty credit exposure was $810 million and GenOn held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $735 million. Approximately 88% of GenOn's exposure before collateral is expected to roll off by the end of 2014. As of June 30, 2013, GenOn Americas Generation’s counterparty credit exposure was $803 million and GenOn Americas Generation held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $728 million. Approximately 88% of GenOn Americas Generation’s exposure before collateral is expected to roll off by the end of 2014. As of June 30, 2013, GenOn Mid-Atlantic’s counterparty credit exposure was $512 million and GenOn Mid-Atlantic held collateral (cash and letters of credit) against those positions of $75 million, resulting in a net exposure of $437 million. Approximately 89% of GenOn Mid-Atlantic’s exposure before collateral is expected to roll off by the end of 2014. Counterparty credit exposure is valued through observable market quotes and discounted at a risk free interest rate. The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for the Registrants with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market, NPNS and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables.

GenOn

Category	Net Exposure (a) (% of Total)
Financial institutions	60	%
Utilities, energy merchants, marketers and other	20	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a) Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $495 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

GenOn Americas Generation

Category	Net Exposure (a) (% of Total)
Financial institutions	61	%
Utilities, energy merchants, marketers and other	19	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a)    Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Americas Generation has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $494 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn Americas Generation does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

GenOn Mid-Atlantic

Category	Net Exposure (a) (% of Total)
Financial institutions	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	100	%

(a)Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Mid-Atlantic has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of the total net exposure discussed above. The aggregate of such counterparties' exposure was $407 million. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, GenOn Mid-Atlantic does not anticipate a material impact on its financial position or results of operations from nonperformance by any of its counterparties.

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Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2013

Significant Accounting Policies [Abstract]

Summary of Significant Accounting Policies (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Summary of Significant Accounting Policies (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Recent Accounting Developments

ASU 2011-11 —Effective January 1, 2013, the Registrants adopted the provisions of ASU No. 2011-11, Balance Sheet (Topic 210) Disclosures about Offsetting Assets and Liabilities, or ASU No. 2011-11, and began providing enhanced disclosures regarding the effect or potential effect of netting arrangements on an entity's financial position by improving information about financial instruments and derivative instruments that either (1) offset in accordance with either ASC 210-20-45 or ASC 810-20-45 or (2) are subject to an enforceable master netting arrangement or similar agreement, irrespective of whether they are offset. Reporting entities are required to disclose both gross and net information about both instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. The disclosures required by ASU No. 2011-11 are required to be adopted retroactively. As this guidance provides only disclosure requirements, the adoption of this standard will not impact the Registrants' results of operations, cash flows or financial position.

ASU 2013-02 (GenOn) - Effective January 1, 2013, GenOn adopted the provisions of ASU No. 2013-02, Other Comprehensive Income (Topic 220) Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, or ASU No. 2013-02, and began reporting the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in net income within the notes to the financial statements if the amount being reclassified is required under U.S. GAAP to be reclassified in its entirety to net income in the same reporting period. For other amounts not required by U.S. GAAP to be reclassified in their entirety to net income in the same reporting period, an entity is required to cross-reference other disclosures which provide additional information about the amounts. The provisions of ASU No. 2013-02 are required to be adopted prospectively. As this guidance provides only presentation requirements, the adoption of this standard did not impact GenOn's results of operations, cash flows or financial position.

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Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Carrying Amount
Fair Value of Financial Instruments
Long-term Debt	$ 3,649	$ 4,185
Fair Value
Fair Value of Financial Instruments
Long-term Debt	3,545	4,195
GenOn Americas Generation | Carrying Amount
Fair Value of Financial Instruments
Long-term Debt	942	946
GenOn Americas Generation | Fair Value
Fair Value of Financial Instruments
Long-term Debt	$ 909	$ 953

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Accounting for Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative
Maximum term of hedging exposure	10 years
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	$ 866	$ 1,116
Gross Amounts of Recognized Derivative Liabilities	(260)	(369)
Cash Collateral (Held)	(134)	(140)
Cash Collateral Posted	49	148
Gross Amounts of Recognized Assets / Liabilities	606	747
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	(219)	242
Net Amount	387	505
Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amounts of Recognized Assets / Liabilities	639	797
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	(219)	(242)
Net Amount	420	555
Interest rate contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amounts of Recognized Assets / Liabilities	(33)
Derivative Instruments	0
Cash Collateral (Held) / Posted	0
Net Amount	(33)
Derivatives Designated as Cash Flow Hedges
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	0	0
Gross Amounts of Recognized Derivative Liabilities	(33)	(50)
Derivatives Designated as Cash Flow Hedges | Interest rate contracts current
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	0	0
Gross Amounts of Recognized Derivative Liabilities	14	9
Derivatives Designated as Cash Flow Hedges | Interest rate contracts long-term
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	0	0
Gross Amounts of Recognized Derivative Liabilities	19	41
Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	866	1,116
Gross Amounts of Recognized Derivative Liabilities	(227)	(319)
Derivatives Not Designated as Cash Flow Hedges | Commodity contracts current
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	523	604
Gross Amounts of Recognized Derivative Liabilities	174	236
Derivatives Not Designated as Cash Flow Hedges | Commodity contracts long-term
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	343	512
Gross Amounts of Recognized Derivative Liabilities	53	83
GenOn Americas Generation
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash Collateral (Held)	(134)	(140)
Cash Collateral Posted	37	91
Gross Amounts of Recognized Assets / Liabilities	575	697
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	219	242
Net Amount	356	455
GenOn Americas Generation | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	952	1,192
Gross Amounts of Recognized Derivative Liabilities	(377)	(495)
GenOn Americas Generation | Derivatives Not Designated as Cash Flow Hedges | Commodity contracts current
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	594	656
Gross Amounts of Recognized Derivative Liabilities	287	362
GenOn Americas Generation | Derivatives Not Designated as Cash Flow Hedges | Commodity contracts long-term
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	358	536
Gross Amounts of Recognized Derivative Liabilities	90	133
GenOn Mid-Atlantic
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash Collateral (Held)	(75)	(57)
Gross Amounts of Recognized Assets / Liabilities	573	694
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	75	57
Net Amount	498	637
GenOn Mid-Atlantic | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	681	849
Gross Amounts of Recognized Derivative Liabilities	(108)	(155)
GenOn Mid-Atlantic | Derivatives Not Designated as Cash Flow Hedges | Commodity contracts current
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	378	394
Gross Amounts of Recognized Derivative Liabilities	73	100
GenOn Mid-Atlantic | Derivatives Not Designated as Cash Flow Hedges | Commodity contracts long-term
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	303	455
Gross Amounts of Recognized Derivative Liabilities	35	55
Short Ton | Coal
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	7,000,000	5,000,000
Short Ton | GenOn Americas Generation | Coal
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	4,000,000	4,000,000
Short Ton | GenOn Mid-Atlantic | Coal
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	4,000,000	4,000,000
MMbtu | Natural Gas
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(163,000,000)	(194,000,000)
MMbtu | GenOn Americas Generation | Natural Gas
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(121,000,000)	(150,000,000)
MMbtu | GenOn Mid-Atlantic | Natural Gas
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(121,000,000)	(150,000,000)
MWh | Power
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(33,000,000)	(43,000,000)
MWh | GenOn Americas Generation | Power
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(19,000,000)	(22,000,000)
MWh | GenOn Mid-Atlantic | Power
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions	(19,000,000)	(22,000,000)
Dollars | Interest Rate Swap
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions, monetary commodity	500	475
Dollars | GenOn Americas Generation | Interest Rate Swap
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions, monetary commodity	0	0
Dollars | GenOn Mid-Atlantic | Interest Rate Swap
Volumetric Underlying Derivative Transactions
Net notional volume buy/(sell) of open derivative transactions, monetary commodity	0	0
Non-affiliate | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	860	1,107
Gross Amounts of Recognized Derivative Liabilities	(214)	(310)
Derivative Instruments	(191)	(260)
Derivative Instruments	191	260
Cash Collateral (Held)	(219)	(243)
Cash Collateral Posted	0	1
Net Amount	450	604
Net Amount	23	(49)
Non-affiliate | Interest rate contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amounts of Recognized Derivative Liabilities	33	(50)
Derivative Instruments	0	0
Cash Collateral Posted	0	0
Net Amount	33	(50)
Non-affiliate | GenOn Americas Generation | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	859	1,107
Gross Amounts of Recognized Derivative Liabilities	(212)	(310)
Derivative Instruments	(191)	(260)
Derivative Instruments	191	260
Cash Collateral (Held)	(219)	(243)
Cash Collateral Posted	0	1
Net Amount	449	604
Net Amount	21	(49)
Non-affiliate | GenOn Mid-Atlantic | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	510	636
Gross Amounts of Recognized Derivative Liabilities	(5)	(3)
Derivative Instruments	(5)	(3)
Derivative Instruments	5	3
Cash Collateral (Held)	(75)	(57)
Cash Collateral Posted	0	0
Net Amount	430	576
Net Amount	0	0
Affiliate | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	6	9
Gross Amounts of Recognized Derivative Liabilities	(13)	(9)
Derivative Instruments	(6)	(9)
Derivative Instruments	6	9
Cash Collateral (Held)	0	0
Cash Collateral Posted	0	0
Net Amount	0	0
Net Amount	7	0
Affiliate | GenOn Americas Generation | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	93	85
Gross Amounts of Recognized Derivative Liabilities	(165)	(185)
Derivative Instruments	(93)	(85)
Derivative Instruments	93	85
Cash Collateral (Held)	0	0
Cash Collateral Posted	0	0
Net Amount	0	0
Net Amount	72	(100)
Affiliate | GenOn Mid-Atlantic | Commodity contracts
Fair Value of Derivative Instruments/Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amount of Recognized Derivative Assets	171	213
Gross Amounts of Recognized Derivative Liabilities	(103)	(152)
Derivative Instruments	(103)	(152)
Derivative Instruments	103	152
Cash Collateral (Held)	0	0
Cash Collateral Posted	0	0
Net Amount	68	61
Net Amount	$ 0	$ 0

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Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor	Jun. 30, 2013 GenOn Mid-Atlantic Successor	Jun. 30, 2013 GenOn Mid-Atlantic Successor	Jun. 30, 2012 GenOn Mid-Atlantic Predecessor	Jun. 30, 2012 GenOn Mid-Atlantic Predecessor	Jun. 30, 2013 Pro Forma GenOn Mid-Atlantic	Dec. 31, 2012 Pro Forma GenOn Mid-Atlantic	Jun. 30, 2013 Pro Forma GenOn Mid-Atlantic Successor	Jun. 30, 2013 Pro Forma GenOn Mid-Atlantic Successor	Jun. 30, 2012 Pro Forma GenOn Mid-Atlantic Predecessor	Jun. 30, 2012 Pro Forma GenOn Mid-Atlantic Predecessor
Income tax provision
Income/(loss) before income taxes	$ 79	$ (154)	$ (224)	$ (256)	$ 64	$ (9)	$ (58)	$ 14
Income tax (benefit)/expense	(6)	(6)	4	4	0	0	0	0			(23)	(4)	22	6
Effective tax rate (as a percent)	(7.59%)	3.90%	(1.79%)	(1.56%)
Statutory tax rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Deferred income taxes									$ 603	$ 598

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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor
Net Income/(Loss)	$ 85	$ (148)	$ (228)	$ (260)
Other comprehensive income net of reclassifications, net of tax of $0:
Unrealized gain/(loss) on derivatives	16	17	(16)	(12)
Defined benefit plans	29	30	1	2
Other, net			1	1
Other comprehensive income/(loss)	45	47	(14)	(9)
Comprehensive income/(loss)	$ 130	$ (101)	$ (242)	$ (269)

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Segment Reporting

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Segment Reporting (GenOn and GenOn Americas Generation)

Segment Reporting (GenOn and GenOn Americas Generation)

Prior to the NRG Merger, GenOn had the following segments: Eastern PJM, Western PJM/MISO, California, Energy Marketing and Other Operations. GenOn Americas Generation previously had the following segments: Eastern PJM, Northeast, California, Energy Marketing and Other Operations. In the fourth quarter of 2012, in conjunction with the NRG Merger, GenOn and GenOn Americas Generation began reporting the following segments: East, South Central, West and Corporate. All GenOn Mid-Atlantic entities are included within the GenOn East segment. There are distinct components with separate operating results and management structures for each segment, which are based on the geographical location of the power generation operations. GenOn and GenOn Americas Generation have recast the data from prior periods to reflect this change in reportable segments to conform to the current year presentation.

GenOn

Successor	Three months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	617		$	—		$	96	$	3		$	716
Operating revenues—affiliate	(4		)	13			—		—			9
Depreciation and amortization	47			2			9		4			62
Income/(loss) before income taxes	126			(2		)	37		(82		)	79
Net income/(loss)	$	126		$	(2	)	$	37	$	(76	)	$	85
Total assets	$	4,379		$	216		$	1,036	$	911		$	6,542

Predecessor	Three months ended June 30, 2012
	East			South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	455		$	8	$	58		$	—		$	521
Depreciation and amortization	71			2		12			5			90
(Loss)/income before income taxes	(115		)	3		(20		)	(92		)	(224		)
Net (loss)/income	$	(115	)	$	3	$	(20	)	$	(96	)	$	(228	)

Successor	Six months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	996		$	—		$	136	$	8		$	1,140
Operating revenues—affiliate	(4		)	19			—		—			15
Depreciation and amortization	91			3			20		7			121
(Loss)/income before income taxes	(9		)	(8		)	17		(154		)	(154		)
Net (loss)/income	$	(9	)	$	(8	)	$	17	$	(148	)	$	(148	)

Predecessor	Six months ended June 30, 2012
	East			South Central			West			Corporate			Total
	(In millions)
Operating revenues	$	1,141		$	8		$	93		$	—		$	1,242
Depreciation and amortization	140			5			23			10			178
Loss before income taxes	(39		)	(1		)	(29		)	(187		)	(256		)
Net loss	$	(39	)	$	(1	)	$	(29	)	$	(191	)	$	(260	)

GenOn Americas Generation

Successor	Three months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	598	$	—	$	68		$	—		$	666
Operating revenues—affiliate	1		14		(43		)	—			(28		)
Depreciation and amortization	19		—		1			—			20
Income/(loss) before income taxes	62		—		—			(21		)	41
Net income/(loss)	$	62	$	—	$	—		$	(21	)	$	41
Total assets	$	2,579	$	—	$	175		$	489		$	3,243

Predecessor	Three months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	427		$	6	$	56	$	—		$	489
Operating revenues—affiliate	54			6		5		—			65
Depreciation and amortization	36			—		3		2			41
(Loss)/income before income taxes	(67		)	5		5		(22		)	(79		)
Net (loss)/income	$	(67	)	$	5	$	5	$	(22	)	$	(79	)

Successor	Six months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	974	$	—	$	91		$	—		$	1,065
Operating revenues—affiliate	134		14		(43		)	—			105
Depreciation and amortization	38		—		3			—			41
Income/(loss) before income taxes	2		—		8			(44		)	(34		)
Net income/(loss)	$	2	$	—	$	8		$	(44	)	$	(34	)

Predecessor	Six months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	1,078		$	6	$	87	$	—		$	1,171
Operating revenues—affiliate	25			6		4		—			35
Depreciation and amortization	71			—		7		3			81
(Loss)/income before income taxes	(1		)	5		5		(42		)	(33		)
Net (loss)/income	$	(1	)	$	5	$	5	$	(42	)	$	(33	)

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CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current Assets
Cash and cash equivalents	$ 248	$ 825
Funds deposited by counterparties	134	140
Restricted cash	34	18
Accounts receivable — trade	186	138
Inventory	437	430
Cash collateral paid in support of energy risk management activities	49	148
Prepayments and other current assets	181	215
Total current assets	1,792	2,518
Property, Plant and Equipment
Property, plant and equipment, net of accumulated depreciation	3,953	3,919
Other Assets
Intangible assets, net of accumulated amortization	67	68
Deferred income taxes	197	209
Other non-current assets	190	235
Total other assets	797	1,024
Total Assets	6,542	7,461
Current Liabilities
Current portion of long-term debt and capital leases	41	32
Deferred income taxes	197	209
Cash collateral received in support of energy risk management activities	134	140
Accrued expenses and other current liabilities	266	338
Total current liabilities	1,013	1,159
Other Liabilities
Long-term debt and capital leases	3,623	4,170
Out-of-market contracts	1,041	1,077
Other non-current liabilities	552	591
Total non-current liabilities	5,288	5,962
Total Liabilities	6,301	7,121
Commitments and Contingencies
Stockholder's Equity
Common stock: $0.001 par value, 1 share authorized and issued at June 30, 2013 and December 31, 2012	0	0
Additional paid-in capital	412	410
Accumulated deficit	(220)	(72)
Accumulated other comprehensive income	49	2
Total Stockholder's Equity	241	340
Total Liabilities and Stockholder's Equity	6,542	7,461
GenOn Mid-Atlantic
Current Assets
Cash and cash equivalents	75	135
Accounts receivable — trade	2	4
Inventory	157	139
Prepayments and other current assets	99	43
Total current assets	711	715
Property, Plant and Equipment
Property, plant and equipment, net of accumulated depreciation	1,111	1,110
Other Assets
Intangible assets, net of accumulated amortization	1	1
Other non-current assets	32	0
Total other assets	336	456
Total Assets	2,158	2,281
Current Liabilities
Current portion of long-term debt and capital leases	7	5
Cash collateral received in support of energy risk management activities	75	57
Accrued expenses and other current liabilities	34	38
Total current liabilities	207	218
Other Liabilities
Long-term debt and capital leases	7	9
Out-of-market contracts	542	554
Other non-current liabilities	55	56
Total non-current liabilities	639	674
Total Liabilities	846	892
Member's Equity
Members' interest	1,312	1,389
Total member's equity	1,312	1,389
Total Liabilities and Member's Equity	2,158	2,281
GenOn Americas Generation
Current Assets
Cash and cash equivalents	75	148
Accounts receivable — trade	160	125
Inventory	222	226
Cash collateral paid in support of energy risk management activities	37	91
Prepayments and other current assets	111	61
Total current assets	1,500	1,505
Property, Plant and Equipment
Property, plant and equipment, net of accumulated depreciation	1,272	1,267
Other Assets
Intangible assets, net of accumulated amortization	66	66
Other non-current assets	47	13
Total other assets	471	615
Total Assets	3,243	3,387
Current Liabilities
Current portion of long-term debt and capital leases	5	5
Cash collateral received in support of energy risk management activities	134	140
Accrued expenses and other current liabilities	69	72
Total current liabilities	701	719
Other Liabilities
Long-term debt and capital leases	949	955
Out-of-market contracts	542	554
Other non-current liabilities	101	103
Total non-current liabilities	1,682	1,745
Total Liabilities	2,383	2,464
Commitments and Contingencies
Member's Equity
Members' interest	860	923
Total member's equity	860	923
Total Liabilities and Member's Equity	3,243	3,387
Non-affiliate
Current Assets
Derivative instruments	518	596
Other Assets
Derivative instruments	342	511
Current Liabilities
Accounts payable	134	189
Derivative instruments	177	237
Other Liabilities
Derivative instruments	70	123
Non-affiliate | GenOn Mid-Atlantic
Current Assets
Derivative instruments	300	285
Other Assets
Derivative instruments	210	351
Current Liabilities
Accounts payable	18	16
Derivative instruments	5	3
Non-affiliate | GenOn Americas Generation
Current Assets
Derivative instruments	517	596
Other Assets
Derivative instruments	342	511
Current Liabilities
Accounts payable	58	69
Derivative instruments	161	228
Other Liabilities
Derivative instruments	51	82
Affiliate
Current Assets
Derivative instruments	5	8
Other Assets
Derivative instruments	1	1
Current Liabilities
Accounts payable	53	6
Derivative instruments	11	8
Other Liabilities
Derivative instruments	2	1
Affiliate | GenOn Mid-Atlantic
Current Assets
Derivative instruments	78	109
Other Assets
Derivative instruments	93	104
Current Liabilities
Accounts payable	0	2
Derivative instruments	68	97
Other Liabilities
Derivative instruments	35	55
Affiliate | GenOn Americas Generation
Current Assets
Note receivable — affiliate	301	198
Derivative instruments	77	60
Other Assets
Derivative instruments	16	25
Current Liabilities
Accounts payable	148	71
Derivative instruments	126	134
Other Liabilities
Derivative instruments	$ 39	$ 51

XML

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor	Jun. 30, 2013 GenOn Americas Generation Successor	Jun. 30, 2013 GenOn Americas Generation Successor	Jun. 30, 2012 GenOn Americas Generation Predecessor	Jun. 30, 2012 GenOn Americas Generation Predecessor	Jun. 30, 2013 GenOn Mid-Atlantic Successor	Jun. 30, 2013 GenOn Mid-Atlantic Successor	Jun. 30, 2012 GenOn Mid-Atlantic Predecessor	Jun. 30, 2012 GenOn Mid-Atlantic Predecessor	Jun. 30, 2013 Non-affiliate Successor	Jun. 30, 2013 Non-affiliate Successor	Jun. 30, 2012 Non-affiliate Predecessor	Jun. 30, 2012 Non-affiliate Predecessor	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor	Jun. 30, 2013 Non-affiliate GenOn Mid-Atlantic Successor	Jun. 30, 2013 Non-affiliate GenOn Mid-Atlantic Successor	Jun. 30, 2012 Non-affiliate GenOn Mid-Atlantic Predecessor	Jun. 30, 2012 Non-affiliate GenOn Mid-Atlantic Predecessor	Jun. 30, 2013 Affiliate Successor	Jun. 30, 2013 Affiliate Successor	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor	Jun. 30, 2013 Affiliate GenOn Mid-Atlantic Successor	Jun. 30, 2013 Affiliate GenOn Mid-Atlantic Successor	Jun. 30, 2012 Affiliate GenOn Mid-Atlantic Predecessor	Jun. 30, 2012 Affiliate GenOn Mid-Atlantic Predecessor
Operating Revenues
Operating revenues													$ 716	$ 1,140	$ 521	$ 1,242	$ 666	$ 1,065	$ 489	$ 1,171	$ 46	$ 6	$ 8	$ 135	$ 9	$ 15	$ (28)	$ 105	$ 65	$ 35	$ 197	$ 335	$ 200	$ 393
Total operating revenues	725	1,155	521	1,242	638	1,170	554	1,206	243	341	208	528	716	1,140		1,242	666	1,065	489	1,171					9	15	(28)	105	65	35
Operating Costs and Expenses
Cost of operations													285	635	506	1,034	160	379	277	537	57	108	43	107	170	310	376	704	267	533	90	177	173	315
Depreciation and amortization	62	121	90	178	20	41	41	81	14	30	30	59
Selling, general and administrative													21	54	64	114	1	2	5	10					19	36	22	42	23	39	17	33	18	30
Acquisition-related transaction and integration costs	22	41
Total operating costs and expenses	579	1,197	660	1,326	579	1,168	613	1,200	178	348	264	511
Operating Income/(Loss)	146	(42)	(139)	(84)	59	2	(59)	6	65	(7)	(56)	17
Other Income/(Expense)
Other income/(expense), net		2		2
Interest expense	(56)	(103)	(85)	(174)													(17)	(33)	(18)	(36)			(1)	(1)			(1)	(3)	(2)	(3)	(1)	(2)	(1)	(2)
Loss on debt extinguishment	(11)	(11)
Total other income (expense), net	(67)	(112)	(85)	(172)	(18)	(36)	(20)	(39)	(1)	(2)	(2)	(3)
Income/(Loss) Before Income Taxes	79	(154)	(224)	(256)	41	(34)	(79)	(33)	64	(9)	(58)	14
Income tax expense/(benefit)	(6)	(6)	4	4	0	0	0	0	0	0	0	0
Net Income/(Loss)	$ 85	$ (148)	$ (228)	$ (260)	$ 41	$ (34)	$ (79)	$ (33)	$ 64	$ (9)	$ (58)	$ 14

XML

Fair Value of Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 866		$ 1,116
Fair Value, Measurements, Recurring | Level 1
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	44		52
Other assets	44	[1]	43	[1]
Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	127		139
Derivative liabilities	44		52
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0
Fair Value, Measurements, Recurring | Level 2
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	202		303
Other assets	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	722		946
Derivative liabilities	169		253
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	33		50
Fair Value, Measurements, Recurring | Level 3
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	14		14
Other assets	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	17		31
Derivative liabilities	14		14
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0
Fair Value, Measurements, Recurring | Fair Value
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	260		369
Other assets	44	[1]	43	[1]
Fair Value, Measurements, Recurring | Fair Value | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	866		1,116
Derivative liabilities	227		319
Fair Value, Measurements, Recurring | Fair Value | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	33		50
GenOn Americas Generation | Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	149		170
Derivative liabilities	103		123
GenOn Americas Generation | Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	784		991
Derivative liabilities	258		358
GenOn Americas Generation | Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	19		31
Derivative liabilities	16		14
GenOn Americas Generation | Fair Value, Measurements, Recurring | Fair Value | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	952		1,192
Derivative liabilities	377		495
GenOn Mid-Atlantic | Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	68		63
Derivative liabilities	20		16
GenOn Mid-Atlantic | Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	609		778
Derivative liabilities	86		138
GenOn Mid-Atlantic | Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	4		8
Derivative liabilities	2		1
GenOn Mid-Atlantic | Fair Value, Measurements, Recurring | Fair Value | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	681		849
Derivative liabilities	$ 108		$ 155

[1] Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

XML

Segment Reporting (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting Information

Schedule of segment reporting information, by segment

GenOn

Successor	Three months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	617		$	—		$	96	$	3		$	716
Operating revenues—affiliate	(4		)	13			—		—			9
Depreciation and amortization	47			2			9		4			62
Income/(loss) before income taxes	126			(2		)	37		(82		)	79
Net income/(loss)	$	126		$	(2	)	$	37	$	(76	)	$	85
Total assets	$	4,379		$	216		$	1,036	$	911		$	6,542

Predecessor	Three months ended June 30, 2012
	East			South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	455		$	8	$	58		$	—		$	521
Depreciation and amortization	71			2		12			5			90
(Loss)/income before income taxes	(115		)	3		(20		)	(92		)	(224		)
Net (loss)/income	$	(115	)	$	3	$	(20	)	$	(96	)	$	(228	)

Successor	Six months ended June 30, 2013
	East			South Central			West		Corporate			Total
	(In millions)
Operating revenues	$	996		$	—		$	136	$	8		$	1,140
Operating revenues—affiliate	(4		)	19			—		—			15
Depreciation and amortization	91			3			20		7			121
(Loss)/income before income taxes	(9		)	(8		)	17		(154		)	(154		)
Net (loss)/income	$	(9	)	$	(8	)	$	17	$	(148	)	$	(148	)

Predecessor	Six months ended June 30, 2012
	East			South Central			West			Corporate			Total
	(In millions)
Operating revenues	$	1,141		$	8		$	93		$	—		$	1,242
Depreciation and amortization	140			5			23			10			178
Loss before income taxes	(39		)	(1		)	(29		)	(187		)	(256		)
Net loss	$	(39	)	$	(1	)	$	(29	)	$	(191	)	$	(260	)

GenOn Americas Generation

Segment Reporting Information

Schedule of segment reporting information, by segment

GenOn Americas Generation

Successor	Three months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	598	$	—	$	68		$	—		$	666
Operating revenues—affiliate	1		14		(43		)	—			(28		)
Depreciation and amortization	19		—		1			—			20
Income/(loss) before income taxes	62		—		—			(21		)	41
Net income/(loss)	$	62	$	—	$	—		$	(21	)	$	41
Total assets	$	2,579	$	—	$	175		$	489		$	3,243

Predecessor	Three months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	427		$	6	$	56	$	—		$	489
Operating revenues—affiliate	54			6		5		—			65
Depreciation and amortization	36			—		3		2			41
(Loss)/income before income taxes	(67		)	5		5		(22		)	(79		)
Net (loss)/income	$	(67	)	$	5	$	5	$	(22	)	$	(79	)

Successor	Six months ended June 30, 2013
	East		South Central		West			Corporate			Total
	(In millions)
Operating revenues	$	974	$	—	$	91		$	—		$	1,065
Operating revenues—affiliate	134		14		(43		)	—			105
Depreciation and amortization	38		—		3			—			41
Income/(loss) before income taxes	2		—		8			(44		)	(34		)
Net income/(loss)	$	2	$	—	$	8		$	(44	)	$	(34	)

Predecessor	Six months ended June 30, 2012
	East			South Central		West		Corporate			Total
	(In millions)
Operating revenues	$	1,078		$	6	$	87	$	—		$	1,171
Operating revenues—affiliate	25			6		4		—			35
Depreciation and amortization	71			—		7		3			81
(Loss)/income before income taxes	(1		)	5		5		(42		)	(33		)
Net (loss)/income	$	(1	)	$	5	$	5	$	(42	)	$	(33	)

XML

Commitments and Contingencies (Details) (USD $)		1 Months Ended						1 Months Ended	12 Months Ended	1 Months Ended			18 Months Ended					1 Months Ended					1 Months Ended
	Feb. 29, 2008 Global Warming Environmental Matters company	Feb. 28, 2013 Pending Natural Gas Litigation Pending Litigation lawsuit	Jul. 31, 2011 Pending Natural Gas Litigation Pending Litigation lawsuit	Jan. 31, 2013 New Source Review Matters Environmental Matters generatingunit	Jun. 30, 2013 New Source Review Matters Environmental Matters generatingunit	Nov. 30, 2011 New Source Review Matters Environmental Matters petition	Dec. 31, 2010 New Source Review Matters Environmental Matters petition	Apr. 30, 2012 Cheswick Class Action Complaint Environmental Matters	Dec. 31, 2008 Cheswick Monarch Mine NOV Environmental Matters	Oct. 31, 2012 Ormond Beach Alleged Federal Clean Water Act Violations Environmental Matters	Sep. 30, 2010 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters Groups	Apr. 30, 2010 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters	Jun. 30, 2012 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters	Jun. 30, 2013 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters facility	Dec. 31, 2011 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters	Jun. 30, 2011 Maryland Fly Ash Facilities GenOn Mid-Atlantic Environmental Matters facility	Jun. 30, 2013 NRG Merger Litigation Pending Litigation lawsuit	Mar. 31, 2013 MDE v. GenOn Chalk Point and GenOn Mid-Atlantic GenOn Mid-Atlantic Environmental Matters	Jan. 31, 2013 MDE v. GenOn Chalk Point and GenOn Mid-Atlantic GenOn Mid-Atlantic Environmental Matters	Jun. 30, 2013 Chapter Eleven Proceedings GenOn Americas Generation Bankruptcy	Dec. 14, 2012 Chapter Eleven Proceedings GenOn Americas Generation Bankruptcy	Dec. 02, 2010 Chapter Eleven Proceedings GenOn Americas Generation Bankruptcy	Jun. 30, 2013 Texas Franchise Audit Tax Matters
Global Warming
Number of Other Companies Named in Lawsuit Filed	23
Loss Contingency, Range of Possible Loss, Maximum	$ 400,000,000
Pending Natural Gas Litigation
Number Lawsuits Filed			5														8
Number of Lawsuits Dismissed		1	4
New Source Review Matters
Number of Administrative Petitions							2
Number Of Administrative Petitions With Published Final Rule						1
Number of Coal Fired Units				2
Reduction In Maximum Allowable So2 Emissions				0.6
Number of Units that Could be Running Option Year Two					1
Cheswick Class Action Complaint
Maximum Distance from Plant Class Action Plaintiffs Live Work								1
Cheswick Monarch Mine NOV
Minimum Civil Penalties which May be Assessed									100,000
Ormond Beach Alleged Federal Clean Water Act Violations
Legal Fees										79,000
Supplemental Environmental Projects										65,000
Monitoring Costs										15,000
Maryland Fly Ash Facilities
Number of Fly Ash Facilities														3
Number of Fly Ash Facilities with Threat of Non Renewal of Water Discharge Permits														3
Period to close and cap existing open disposal cells												1 year
Number of intervening parties in the proceeding											4
Number of Matters to Settle																3
Amount accrued for alleged past violations															1,900,000
Amount accrued for alleged prospective violations													600,000
Amount accrued for civil pnalty due													2,500,000
Amount accrued for estimated cost of proposed technical solution															47,000,000
Purported class actions related to NRG Merger
Number of consolidated court cases																	1
Maryland Department of the Environment v. GenOn Chalk Point and GenOn Mid-Atlantic
Number of Permits That Regulate Polution Discharge Elimination																			3
Days to Comply																		60 days
Chapter Eleven Proceedings
GenOn Energy Holdings common stock shares reserved for unresolved claims																				461,000
Number of reserved shares for disputed Chapter 11 claims converted into reserved of GenOn common stock																						1,300,000
Number of reserved shares for disputed Chapter 11 claims converted into reserved of NRG common stock																					159,000
Texas Franchise Audit
Income Tax Examination, Penalties and Interest Accrued																							72,000,000
Income Tax Examination, Interest Accrued																							29,000,000
Tax Adjustments, Settlements, and Unusual Provisions																							$ 11,000,000

XML

Debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		1 Months Ended
	Jun. 30, 2013 Senior Secured Notes 2014	Jun. 30, 2013 Senior Secured Notes 2014	Jun. 30, 2013 Marsh Landing	May 31, 2013 GenOn Energy Holdings Marsh Landing
Debt
Redeemed debt, face value	$ 575	$ 575
Repurchase/redemption price, percentage of face amount (as a percent)	1.06778
Loss on debt extinguishment		11
Letters of credit issued and outstanding at period end, amount			26
Issued letters of credit returned, amount				$ 80

XML

Segment Reporting (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended						3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor Conventional Power Generation East	Jun. 30, 2013 Successor Conventional Power Generation East	Jun. 30, 2013 Successor Conventional Power Generation South Central	Jun. 30, 2013 Successor Conventional Power Generation South Central	Jun. 30, 2013 Successor Conventional Power Generation West	Jun. 30, 2013 Successor Conventional Power Generation West	Jun. 30, 2013 Successor Corporate	Jun. 30, 2013 Successor Corporate	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor Conventional Power Generation East	Jun. 30, 2012 Predecessor Conventional Power Generation East	Jun. 30, 2012 Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Predecessor Conventional Power Generation West	Jun. 30, 2012 Predecessor Conventional Power Generation West	Jun. 30, 2012 Predecessor Corporate	Jun. 30, 2012 Predecessor Corporate	Jun. 30, 2013 GenOn Americas Generation	Dec. 31, 2012 GenOn Americas Generation	Jun. 30, 2013 GenOn Americas Generation Successor	Jun. 30, 2013 GenOn Americas Generation Successor	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 GenOn Americas Generation Successor Corporate	Jun. 30, 2013 GenOn Americas Generation Successor Corporate	Jun. 30, 2012 GenOn Americas Generation Predecessor	Jun. 30, 2012 GenOn Americas Generation Predecessor	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 GenOn Americas Generation Predecessor Corporate	Jun. 30, 2012 GenOn Americas Generation Predecessor Corporate	Jun. 30, 2013 Non-affiliate Successor	Jun. 30, 2013 Non-affiliate Successor	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation East	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation East	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation South Central	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation South Central	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation West	Jun. 30, 2013 Non-affiliate Successor Conventional Power Generation West	Jun. 30, 2013 Non-affiliate Successor Corporate	Jun. 30, 2013 Non-affiliate Successor Corporate	Jun. 30, 2012 Non-affiliate Predecessor	Jun. 30, 2012 Non-affiliate Predecessor Conventional Power Generation East	Jun. 30, 2012 Non-affiliate Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Non-affiliate Predecessor Conventional Power Generation West	Jun. 30, 2012 Non-affiliate Predecessor Corporate	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Corporate	Jun. 30, 2013 Non-affiliate GenOn Americas Generation Successor Corporate	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Corporate	Jun. 30, 2012 Non-affiliate GenOn Americas Generation Predecessor Corporate	Jun. 30, 2013 Affiliate Successor	Jun. 30, 2013 Affiliate Successor	Jun. 30, 2013 Affiliate Successor Conventional Power Generation East	Jun. 30, 2013 Affiliate Successor Conventional Power Generation East	Jun. 30, 2013 Affiliate Successor Conventional Power Generation South Central	Jun. 30, 2013 Affiliate Successor Conventional Power Generation South Central	Jun. 30, 2013 Affiliate Successor Conventional Power Generation West	Jun. 30, 2013 Affiliate Successor Conventional Power Generation West	Jun. 30, 2013 Affiliate Successor Corporate	Jun. 30, 2013 Affiliate Successor Corporate	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation East	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation South Central	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Conventional Power Generation West	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Corporate	Jun. 30, 2013 Affiliate GenOn Americas Generation Successor Corporate	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation East	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation South Central	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Conventional Power Generation West	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Corporate	Jun. 30, 2012 Affiliate GenOn Americas Generation Predecessor Corporate
Segment Reporting Information
Operating revenues			$ 725	$ 1,155									$ 521	$ 1,242	$ 455		$ 8		$ 58		$ 0				$ 638	$ 1,170									$ 554	$ 1,206									$ 716	$ 1,140	$ 617	$ 996	$ 0	$ 0	$ 96	$ 136	$ 3	$ 8	$ 1,242	$ 1,141	$ 8	$ 93	$ 0	$ 666	$ 1,065	$ 598	$ 974	$ 0	$ 0	$ 68	$ 91	$ 0	$ 0	$ 489	$ 1,171	$ 427	$ 1,078	$ 6	$ 6	$ 56	$ 87	$ 0	$ 0	$ 9	$ 15	$ (4)	$ (4)	$ 13	$ 19	$ 0	$ 0	$ 0	$ 0	$ (28)	$ 105	$ 1	$ 134	$ 14	$ 14	$ (43)	$ (43)	$ 0	$ 0	$ 65	$ 35	$ 54	$ 25	$ 6	$ 6	$ 5	$ 4	$ 0	$ 0
Depreciation and amortization			62	121	47	91	2	3	9	20	4	7	90	178	71	140	2	5	12	23	5	10			20	41	19	38	0	0	1	3	0	0	41	81	36	71	0	0	3	7	2	3
Income/(loss) before income taxes			79	(154)	126	(9)	(2)	(8)	37	17	(82)	(154)	(224)	(256)	(115)	(39)	3	(1)	(20)	(29)	(92)	(187)			41	(34)	62	2	0	0	0	8	(21)	(44)	(79)	(33)	(67)	(1)	5	5	5	5	(22)	(42)
Net income/(loss)			85	(148)	126	(9)	(2)	(8)	37	17	(76)	(148)	(228)	(260)	(115)	(39)	3	(1)	(20)	(29)	(96)	(191)			41	(34)	62	2	0	0	0	8	(21)	(44)	(79)	(33)	(67)	(1)	5	5	5	5	(22)	(42)
Total assets	$ 6,542	$ 7,461	$ 6,542	$ 6,542	$ 4,379	$ 4,379	$ 216	$ 216	$ 1,036	$ 1,036	$ 911	$ 911											$ 3,243	$ 3,387	$ 3,243	$ 3,243	$ 2,579	$ 2,579	$ 0	$ 0	$ 175	$ 175	$ 489	$ 489

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Debt

6 Months Ended

Jun. 30, 2013

Long Term Debt Disclosure [Abstract]

Debt (GenOn)

Debt (GenOn)

Redemption of Senior Unsecured Notes, Due 2014, or 2014 Senior Notes

In June 2013, GenOn redeemed all of the 2014 Senior Notes, with an aggregate outstanding principal amount of $575 million, at a redemption percentage of 106.778% of face value, as well, as any accrued and unpaid interest as of the redemption date. In connection with the redemption, an $11 million loss on the debt extinguishment of the 2014 Senior Notes was recorded during the three months ended June 30, 2013 which primarily consisted of a make whole premium payment offset by the write-off of unamortized premium.

NRG Marsh Landing Credit Agreement Term Conversion

In May 2013, NRG Marsh Landing met the conditions under the credit agreement to convert the construction loan for the facility to a term loan which will amortize on a predetermined basis. Prior to term conversion, NRG Marsh Landing drew the remaining funds available under the facility in order to pay costs due for construction. NRG Marsh Landing also issued a $26 million letter of credit under the facility in support of its debt service requirements. Concurrently with the term conversion, the $80 million cash collateralized letter of credit issued by GenOn Energy Holdings on behalf of NRG Marsh Landing in support of its collateral requirements under the PPA with PG&E was returned and the related letter of credit facility was terminated.

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Fair Value of Financial Instruments (Details 3) (Derivatives, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		18 Months Ended		3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		18 Months Ended		3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		18 Months Ended
	Jun. 30, 2013 Successor		Jun. 30, 2013 Successor		Jun. 30, 2012 Predecessor		Jun. 30, 2012 Predecessor		Jun. 30, 2012 Predecessor		Jun. 30, 2013 GenOn Americas Generation Successor		Jun. 30, 2012 GenOn Americas Generation Successor	Jun. 30, 2013 GenOn Americas Generation Successor		Jun. 30, 2012 GenOn Americas Generation Predecessor		Jun. 30, 2012 GenOn Americas Generation Predecessor		Jun. 30, 2012 GenOn Americas Generation Predecessor		Jun. 30, 2013 GenOn Mid-Atlantic Successor		Jun. 30, 2012 GenOn Mid-Atlantic Successor	Jun. 30, 2013 GenOn Mid-Atlantic Successor		Jun. 30, 2012 GenOn Mid-Atlantic Predecessor		Jun. 30, 2012 GenOn Mid-Atlantic Predecessor		Jun. 30, 2012 GenOn Mid-Atlantic Predecessor
Fair Value Asset and Liabilities, Measured on Recurring Basis, Unobservable Input Changes
Fair Value, Assets And Liabilities, Level 1 to Level 2 Transfers Amount	$ 0		$ 0		$ 0		$ 0		$ 0		$ 0			$ 0		$ 0		$ 0		$ 0		$ 0			$ 0		$ 0		$ 0		$ 0
Fair Value, Assets And Liabilities, Level 2 To Level 1 Transfers Amount	0		0		0		0		0		0			0		0		0		0		0			0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability Transfers into Level 3	0		0						0		0		0	0						0		0		0	0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability, Transfers out of Level 3	0		0		0				0		0			0		0				0		0			0		0				0
Reconciliation of the beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements
Beginning Balance	(6)	[1]	17	[1]	(36)	[1]	(31)	[1]			(6)	[1]		17	[1]	(30)	[1]	(32)	[1]			(6)	[2]		7	[2]	(88)	[2]	(64)	[2]
Total gains and losses (realized/unrealized) included in earnings	3	[1]	(16)	[1]	(95)	[1]	(100)	[1]			3	[1]		(16)	[1]	(83)	[1]	(81)	[1]			2	[2]		(7)	[2]	(50)	[2]	(74)	[2]
Purchases	6	[1]	2	[1]	0	[1]	0	[1]			6	[1]		2	[1]	0	[1]	0	[1]			6	[2]		2	[2]	0	[2]	0	[2]
Ending Balance	3	[1]	3	[1]	(131)	[1]	(131)	[1]	(131)	[1]	3	[1]		3	[1]	(113)	[1]	(113)	[1]	(113)	[1]	2			2		(138)		(138)		(138)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end	$ 14	[1]	$ 1	[1]	$ (131)	[1]	$ (136)	[1]			$ 14			$ 1	[1]	$ (121)	[1]	$ (120)	[1]			$ 8	[2]		$ 1	[2]	$ (90)	[2]	$ (115)	[2]

[1] Consists of derivative assets and liabilities, net.

[2] Consists of derivative assets and liabilities, net

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Related Party Transactions

6 Months Ended

Jun. 30, 2013

Related Party Transactions [Abstract]

Related Party Transactions (GenOn, GenOn Americas Generaiton, GenOn Mid-Atlantic)

Related Party Transactions (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Services Agreement with NRG (GenOn)

Subsequent to the NRG Merger, NRG provides GenOn with various management, personnel and other services, which include human resources, regulatory and public affairs, accounting, tax, legal, information systems, treasury, risk management, commercial operations, and asset management, as set forth in the Services Agreement. The initial term of the Services Agreement is through December 31, 2013, with an automatic renewal absent a request for termination. The fee charged is determined based on a fixed amount as described in the Services Agreement and was calculated based on historical GenOn expenses prior to the NRG Merger. The annual fees under the Services Agreement are approximately $193 million. NRG charges these fees on a monthly basis, less amounts incurred directly by GenOn. Management has concluded that this method of charging overhead costs is reasonable. For the three and six months endedJune 30, 2013, GenOn recorded costs related to these services of $14 million and $25 million, respectively, as selling, general and administrative — affiliate.

Administrative Services Provided by NRG for the Successor Period and Provided by GenOn Energy for the Predecessor Period

Prior to the NRG Merger, GenOn provided GenOn Americas Generation and GenOn Mid-Atlantic with various management, personnel and other services directly relating to their facilities. GenOn Americas Generation and GenOn Mid-Atlantic reimbursed GenOn for amounts equal to the costs of providing such services. In addition, GenOn's corporate overhead costs were allocated to its subsidiaries based on each operating subsidiary's planned operating expenses relative to all operating subsidiaries of GenOn. Subsequent to the NRG Merger, NRG provides GenOn Americas Generation and GenOn Mid-Atlantic with various management, personnel and other services consistent with those set forth in the Services Agreement discussed above between NRG and GenOn. GenOn's costs incurred under the Services Agreement with NRG are allocated to its subsidiaries based on each operating subsidiary's planned operating expenses relative to all operating subsidiaries of GenOn. These allocations and charges are not necessarily indicative of what would have been incurred had GenOn Americas Generation and GenOn Mid-Atlantic been unaffiliated entities. Management has concluded that this method of charging overhead costs is reasonable.

The following costs were incurred under these arrangements:

GenOn Americas Generation

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	35	$	38	$	70	$	79
Allocated costs:
Cost of operations — affiliate	1		8		5		17
Selling, general and administrative — affiliate	22		23		42		39
Total	$	58	$	69	$	117	$	135

GenOn Mid-Atlantic

	Successor		Predecessor		Successor		Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Direct costs:
Cost of operations — affiliate	$	21	$	24	$	44	$	48
Allocated costs:
Cost of operations — affiliate	—		2		3		6
Selling, general and administrative — affiliate	17		18		33		30
Total	$	38	$	44	$	80	$	84

In addition, for the successor period, NRG provided services to certain of GenOn's operating subsidiaries including the execution of contracts, including economic hedges to reduce price risk. These transactions are recorded as operating revenues — affiliate and cost of operations — affiliate in GenOn's consolidated statement of operations. Amounts due from and to NRG are recorded as accounts receivable — affiliate or accounts payable — affiliate.

Services Provided by GenOn Energy Management (GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn Americas Generation

GenOn Energy Management provides services to certain of GenOn's indirect operating subsidiaries through power, fuel supply and services agreements. The services include the bidding and dispatch of the generating units, fuel procurement and the execution of contracts, including economic hedges to reduce price risk. These transactions are recorded as operating revenues — affiliate or cost of operations — affiliate in GenOn Americas Generation's consolidated statements of operations. Amounts due from and to GenOn's indirect operating subsidiaries are recorded as accounts receivable — affiliate or accounts payables — affiliate. Substantially all energy marketing overhead expenses are allocated to GenOn's operating subsidiaries by GenOn Energy Management. For the three months ended June 30, 2013 and 2012, GenOn Americas Generation recorded a reduction to cost of operations — affiliate of $2 million and $6 million, respectively, and for the six months ended June 30, 2013 and 2012, GenOn Americas Generation recorded a reduction to cost of operations — affiliate of $4 million and $12 million, respectively, related to the allocations of energy marketing overhead expenses to affiliates outside of GenOn Americas Generation.

GenOn Mid-Atlantic

GenOn Mid-Atlantic receives services from GenOn Energy Management which include the bidding and dispatch of the generating units, procurement of fuel and other products and the execution of contracts, including economic hedges, to reduce price risk. These transactions are recorded as operating revenues — affiliate or cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations. Amounts due to and from GenOn Energy Management under the power, fuel supply and services agreements are recorded as accounts payables — affiliate or accounts receivables — affiliate. Under these agreements, GenOn Energy Management resells GenOn Mid-Atlantic's energy products in the PJM spot and forward markets and to other third parties. GenOn Mid-Atlantic pays the amount received by GenOn Energy Management for such capacity and energy. GenOn Mid-Atlantic has counterparty credit risk in the event that GenOn Energy Management is unable to collect amounts owed from third parties for the resale of GenOn Mid-Atlantic's energy products. Substantially all energy marketing overhead expenses are allocated to GenOn's operating subsidiaries. For the three months ended June 30, 2013 and 2012, GenOn Mid-Atlantic incurred an insignificant amount and $1 million of energy marketing overhead expense, respectively. For the six months ended June 30, 2013 and 2012, GenOn Mid-Atlantic incurred $1 million and $2 million of energy marketing overhead expense, respectively. These costs were included in cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations.

Credit Agreement with NRG (GenOn)

In connection with the closing of the NRG Merger, GenOn and NRG Americas entered into a secured intercompany revolving credit agreement with NRG.  This credit agreement provides for a $500 million revolving credit facility, all of which is available for revolving loans and letters of credit. At June 30, 2013 and December 31, 2012, letters of credit of $296 million and $261 million, respectively, were issued and outstanding under the NRG credit agreement on behalf of GenOn. At June 30, 2013 and December 31, 2012, letters of credit of $108 million and $166 million, respectively, were issued on behalf of GenOn Americas Generation. At June 30, 2013 and December 31, 2012, letters of credit of $78 million and $113 million, respectively, were issued on behalf of GenOn Mid-Atlantic. At June 30, 2013 and December 31, 2012, no loans were outstanding under this credit agreement.  In connection with the execution of the agreement, certain of GenOn's subsidiaries, as guarantors, entered into a guarantee agreement pursuant to which these guarantors guaranteed amounts borrowed and obligations incurred under the credit agreement. The credit agreement has a three year maturity and is payable at maturity, subject to certain exceptions primarily related to asset sales not in the ordinary course of business and borrowings of debt. In addition, the guarantors are restricted from incurring additional liens on their assets. At GenOn's election, the interest rate per year applicable to the loans under the credit agreement will be determined by reference to either (i) the base rate plus 2.50% per year or (ii) the LIBOR rate plus 3.50% per year. In addition, the credit agreement contains customary covenants and events of default.

Intercompany Cash Management Program (GenOn Americas Generation)

GenOn Americas Generation and certain of its subsidiaries participate in separate intercompany cash management programs whereby cash balances at GenOn Americas Generation and the respective participating subsidiaries are transferred to central concentration accounts to fund working capital and other needs of the respective participants. The balances under this program are reflected as notes receivable — affiliate or notes payable — affiliate, as appropriate. The notes are due on demand and accrue interest on the net position, which is payable quarterly, at the short term yield of the Federated Investors Treasury Obligation Fund or such other fund designated by GenOn Energy Holdings. At June 30, 2013 and December 31, 2012, GenOn Americas Generation had a net current note receivable from GenOn Energy Holdings of $301 million and $198 million, respectively, related to its intercompany cash management program. For the three and six months ended June 30, 2013 and 2012, GenOn Americas Generation earned an insignificant amount of net interest income related to these notes.

Purchased Emission Allowances (GenOn Mid-Atlantic)

GenOn Energy Management maintains an inventory of certain purchased emission allowances related to the Regional Greenhouse Gas Initiative on behalf of GenOn Mid-Atlantic. The emission allowances are sold by GenOn Energy Management to GenOn Mid-Atlantic as they are needed for operations. GenOn Mid-Atlantic purchases emission allowances from GenOn Energy Management at GenOn Energy Management's original cost to purchase the allowances. For allowances that have been purchased by GenOn Energy Management from a GenOn Energy affiliate, the price paid by GenOn Energy Management is determined by market indices.

Emission allowances purchased from GenOn Energy Management that were utilized during the three months ended June 30, 2013 and 2012 were $4 million and $4 million, respectively, and during the six months ended June 30, 2013 and 2012 were $8 million and $7 million, respectively, and were recorded in cost of operations — affiliate in GenOn Mid-Atlantic's consolidated statements of operations.

Sale of NRG Marsh Landing Holdings LLC to NRG Yield LLC (GenOn)

On July 22, 2013, concurrent with the initial public offering of NRG Yield, Inc., GenOn sold its ownership interests in NRG Marsh Landing Holdings LLC to NRG Yield LLC for a purchase price of $199 million. The net assets of NRG Marsh Landing Holdings LLC were $168 million at the time of the sale resulting in the recognition of additional paid-in capital of $31 million.

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Accounting for Derivative Instruments and Hedging Activities

6 Months Ended

Jun. 30, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Accounting for Derivative Instruments and Hedging Activities (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Accounting for Derivative Instruments and Hedging Activities (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

This footnote should be read in conjunction with the complete description under Note 6, Accounting for Derivative Instruments and Hedging Activities, to the Registrants' 2012 Form 10-K.

Energy-Related Commodities(GenOn)

As of June 30, 2013, GenOn had energy-related derivative financial instruments extending through 2017.

Interest Rate Swaps (GenOn)

In 2010, NRG Marsh Landing entered into interest rate protection agreements (interest rate swaps) in connection with its project financing, which have been designated as cash flow hedges. NRG Marsh Landing entered into the interest rate swaps to reduce the risks with respect to the variability of the interest rates for the term loans. As of June 30, 2013, the maximum length of time GenOn is hedging its exposure to the variability in future cash flows that may result from changes in interest rates is 10 years.

Volumetric Underlying Derivative Transactions (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The following table summarizes the net notional volume buy/(sell) of the Registrants’ open derivative transactions broken out by commodity, excluding those derivatives that qualified for the NPNS exception as of June 30, 2013 and December 31, 2012. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date.

		GenOn				GenOn Americas Generation				GenOn Mid-Atlantic
		Total Volume				Total Volume				Total Volume
		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012
Commodity	Units	(In millions)
Coal	Short Ton	7		5		4		4		4		4
Natural Gas	MMBtu	(163)		(194)		(121)		(150)		(121)		(150)
Power	MWh	(33)		(43)		(19)		(22)		(19)		(22)
Interest	Dollars	$	500	$	475	$	—	$	—	$	—	$	—

Fair Value of Derivative Instruments (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The following tables summarize the fair value within the derivative instrument valuation on the balance sheet:

GenOn

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Designated as Cash Flow Hedges:
Interest rate contracts current	$	—	$	—	$	14	$	9
Interest rate contracts long-term	—		—		19		41
Total Derivatives Designated as Cash Flow Hedges	—		—		33		50
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	523		604		174		236
Commodity contracts long-term	343		512		53		83
Total Derivatives Not Designated as Cash Flow Hedges	866		1,116		227		319
Total Derivatives	$	866	$	1,116	$	260	$	369

GenOn Americas Generation

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	594	$	656	$	287	$	362
Commodity contracts long-term	358		536		90		133
Total Derivatives Not Designated as Cash Flow Hedges	$	952	$	1,192	$	377	$	495

GenOn Mid-Atlantic

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	378	$	394	$	73	$	100
Commodity contracts long-term	303		455		35		55
Total Derivatives Not Designated as Cash Flow Hedges	$	681	$	849	$	108	$	155

The Registrants have elected to present derivative assets and liabilities on the balance sheet on a trade-by-trade basis and do not offset amounts at the counterparty master agreement level. In addition, collateral received or paid on the Registrants' derivative assets or liabilities are recorded on a separate line item on the balance sheet. The following tables summarize the offsetting of derivatives by counterparty master agreement level and collateral received or paid:

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	860		$	(191	)	$	(219	)	$	450
Derivative assets - affiliate	6			(6		)	—			—
Derivative liabilities	(214		)	191			—			(23		)
Derivative liabilities - affiliate	(13		)	6			—			(7		)
Total commodity contracts	639			—			(219		)	420
Interest rate contracts:
Derivative liabilities	(33		)	—			—			(33		)
Total interest rate contracts	(33		)	—			—			(33		)
Total derivative instruments	$	606		$	—		$	(219	)	$	387

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	859		$	(191	)	$	(219	)	$	449
Derivative assets - affiliate	93			(93		)	—			—
Derivative liabilities	(212		)	191			—			(21		)
Derivative liabilities - affiliate	(165		)	93			—			(72		)
Total derivative instruments	$	575		$	—		$	(219	)	$	356

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	510		$	(5	)	$	(75	)	$	430
Derivative assets - affiliate	171			(103		)	—			68
Derivative liabilities	(5		)	5			—			—
Derivative liabilities - affiliate	(103		)	103			—			—
Total derivative instruments	$	573		$	—		$	(75	)	$	498

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	9			(9		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(9		)	9			—			—
Total commodity contracts	797			—			(242		)	555
Interest rate contracts:
Derivative liabilities	(50		)	—			—			(50		)
Total derivative instruments	$	747		$	—		$	(242	)	$	505

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	85			(85		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(185		)	85			—			(100		)
Total derivative instruments	$	697		$	—		$	(242	)	$	455

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	636		$	(3	)	$	(57	)	$	576
Derivative assets - affiliate	213			(152		)	—			61
Derivative liabilities	(3		)	3			—			—
Derivative liabilities - affiliate	(152		)	152			—			—
Total derivative instruments	$	694		$	—		$	(57	)	$	637

Accumulated Other Comprehensive Loss (GenOn)

The following table summarizes the effects on GenOn's accumulated OCI balance attributable to cash flow hedge derivatives:

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Accumulated OCI balance, beginning of period	$	2		$	(30	)	$	1		$	(34	)
Recognized in OCI on interest rate derivatives	17			(15		)	19			(11		)
Reclassified from accumulated OCI into earnings(a)(b)	(1		)	(1		)	(2		)	(1		)
Accumulated OCI balance, end of period	$	18		$	(46	)	$	18		$	(46	)

(a) Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded in interest expense.

(b) All of the forecasted transactions (future interest payments) were deemed probable of occurring; therefore, no cash flow hedges were discontinued and no amount was recognized in GenOn’s results of operations as a result of discontinued cash flow hedges.

Because a significant portion of the interest expense incurred by NRG Marsh Landing during construction was capitalized, amounts included in accumulated other comprehensive loss associated with construction period interest payments will be reclassified into earnings over the expected useful life of the Marsh Landing generating facility, which commenced commercial operations on May 1, 2013.

Impact of Derivative Instruments on the Statements of Operations (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow hedges are reflected in current period earnings.

The following tables summarize the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Registrants’ statements of operations. These amounts are included within operating revenues and cost of operations.

GenOn

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(99	)	$	(99	)	$	(197	)	$	(228	)
Net unrealized gains/(losses) on open positions related to economic hedges	161			(54		)	38			182
Total unrealized mark-to-market gains/(losses) for economic hedging activities	62			(153		)	(159		)	(46		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	63		$	(142	)	$	(159	)	$	(42	)

	Successor		Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	45	$	(102	)	$	(190	)	$	41
Cost of operations	18		(40		)	31			(83		)
Total impact to statements of operations	$	63	$	(142	)	$	(159	)	$	(42	)

GenOn Americas Generation

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(75	)	$	(73	)	$	(149	)	$	(173	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(46		)	26			110
Total unrealized mark-to-market gains/(losses) for economic hedging activities	11			(119		)	(123		)	(63		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	12		$	(108	)	$	(123	)	$	(59	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(2	)	$	(68	)	$	(153	)	$	7
Cost of operations	14			(40		)	30			(66		)
Total impact to statements of operations	$	12		$	(108	)	$	(123	)	$	(59	)

GenOn Mid-Atlantic

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(76	)	$	(73	)	$	(150	)	$	(175	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(40		)	28			104
Total unrealized gains/(losses)	$	10		$	(113	)	$	(122	)	$	(71	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(4	)	$	(66	)	$	(152	)	$	1
Cost of operations	14			(47		)	30			(72		)
Total impact to statements of operations	$	10		$	(113	)	$	(122	)	$	(71	)

Credit Risk Related Contingent Features (GenOn and GenOn Americas Generation)

Certain of GenOn and GenOn Americas Generation’s hedging agreements contain provisions that require the Registrants to post additional collateral if the counterparty determines that there has been deterioration in credit quality, generally termed "adequate assurance" under the agreements, or require the Registrants to post additional collateral if there were a one notch downgrade in the Registrants’ credit rating. The collateral required for contracts that have adequate assurance clauses that are in net liability positions as of June 30, 2013 was $15 million for GenOn and GenOn Americas Generation. The collateral required for contracts with credit rating contingent features that are in a net liability position as of June 30, 2013, was $1 million for GenOn and GenOn Americas Generation. In addition, GenOn and GenOn Americas Generation are parties to certain marginable agreements under which they have net liability positions, but the counterparties have not called for collateral due, which is approximately $4 million for GenOn and GenOn Americas Generation as of June 30, 2013. At June 30, 2013, GenOn Mid-Atlantic did not have any financial instruments with credit risk related contingent features.

See Note 4, Fair Value of Financial Instruments, for discussion regarding concentration of credit risk.

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CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 Successor	Jun. 30, 2013 Successor GenOn Americas Generation	Jun. 30, 2013 Successor GenOn Mid-Atlantic	Jun. 30, 2013 Successor Affiliate GenOn Americas Generation	Jun. 30, 2013 Successor Affiliate GenOn Mid-Atlantic	Jun. 30, 2012 Predecessor	Jun. 30, 2012 Predecessor GenOn Americas Generation	Jun. 30, 2012 Predecessor GenOn Mid-Atlantic	Jun. 30, 2012 Predecessor Affiliate GenOn Americas Generation	Jun. 30, 2012 Predecessor Affiliate GenOn Mid-Atlantic
Cash Flows from Operating Activities
Net Income/(Loss)	$ (148)	$ (34)	$ (9)			$ (260)	$ (33)	$ 14
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Depreciation and amortization	121	41	30			178	81	59
Amortization of financing costs and debt discount/premiums	(43)	(4)				8
Amortization of acquired and out-of-market contracts	(36)	(12)	(12)			(22)
Amortization of unearned equity compensation	7					9
Adjustment to loss on debt extinguishment	(28)
Loss/(gain) on disposals and sales of assets	1	4	4			(8)	(1)	(1)
Changes in derivative instruments	159	122	121			42	58	71
Excess materials and supplies inventory reserve						35	6	4
Lower of cost or market inventory adjustments						65	34	34
Advance settlement of out-of-market contract obligation						(20)
Potomac River settlement reversal						(31)	(31)	(31)
Large scale remediation and settlement costs						(3)	(3)	(3)
Other, net						2
Changes in collateral deposits supporting energy risk management activities	99	48	18			9	230	168
Cash provided/(used) by changes in other working capital	(22)	(51)	(112)			(203)	(123)	(113)
Net Cash Provided/(Used) by Operating Activities	110	114	40			(199)	218	202
Cash Flows from Investing Activities:
Capital expenditures	(190)	(35)	(30)			(342)	(151)	(134)
Proceeds from sale of assets, net	1					14
(Increase)/decrease in restricted cash, net	(16)					167	166	166
Decrease/(increase) in notes receivable - affiliate				(103)					13
Purchase of emission allowances, net of proceeds	(14)	(14)
Net Cash Provided/(Used) by Investing Activities	(219)	(152)	(30)			(161)	28	32
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	110					148
Payments for short and long-term debt	(578)	(2)	(2)			(6)	(2)	(2)
Increase/(decrease) of notes payable-affiliate					2				32
Capital contributions				37
Distributions to member				(70)	(70)				(100)	(100)
Net Cash Provided/(Used) by Fnancing Activities	(468)	(35)	(70)			142	(70)	(102)
Net Increase (Decrease) in Cash and Cash Equivalents	(577)	(73)	(60)			(218)	176	132
Cash and Cash Equivalents at Beginning of Period						1,539	267	68
Cash and Cash Equivalents at End of Period	248	75	75			1,321	443	200
Supplemental Disclosures
Interest paid, net of amounts capitalized	137	36				165	35
Income taxes paid, net of refunds received	$ (79)					$ 11

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Accounting for Derivative Instruments and Hedging Activities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013 Successor		Jun. 30, 2013 Successor		Jun. 30, 2012 Predecessor		Jun. 30, 2012 Predecessor
Effects GenOn's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives
Accumulated OCI balance, beginning of period	$ 2		$ 1		$ (30)		$ (34)
Recognized in OCI on interest rate derivatives	17		19		(15)		(11)
Reclassified from accumulated OCI into earnings	(1)	[1],[2]	(2)	[1],[2]	(1)	[1],[2]	(1)	[1],[2]
Accumulated OCI balance, end of period	$ 18		$ 18		$ (46)		$ (46)

[1] All of the forecasted transactions (future interest payments) were deemed probable of occurring; therefore, no cash flow hedges were discontinued and no amount was recognized in GenOn’s results of operations as a result of discontinued cash flow hedges.

[2] Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded in interest expense.

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Environmental Matters

6 Months Ended

Jun. 30, 2013

Environmental Matters Disclosure [Abstract]

Environmental Matters (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Environmental Matters (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

The Registrants are subject to a wide range of environmental regulations in the development, ownership, construction and operation of projects. These laws and regulations generally require that governmental permits and approvals be obtained before construction and during operation of power plants. Environmental regulations have become increasingly stringent and the Registrants expect this trend to continue. The electric generation industry is likely to face new requirements to address various emissions, including greenhouse gases, as well as combustion byproducts, water discharge and use, and threatened and endangered species. In general, future laws and regulations are expected to require the addition of emissions controls or other environmental quality equipment or the imposition of certain restrictions on the operations of the Registrants' facilities, which could have a material effect on the Registrants' operations.

Environmental Capital Expenditures

Based on current rules, technology and plans based on proposed rules, GenOn estimates that environmental capital expenditures from 2013 through 2017 required to meet GenOn's regulatory environmental laws will be approximately $208 million for GenOn, which includes $46 million for GenOn Americas Generation. The amount for GenOn Americas Generation includes $4 million for GenOn Mid-Atlantic. These costs are primarily associated with controls to satisfy MATS at Conemaugh and NO_x controls for Sayreville and Gilbert. The Registrants continue to explore cost effective compliance alternatives to further reduce costs.

East Region

The EPA and various states are investigating compliance of coal-fueled electric generating facilities with the pre-construction permitting requirements of the CAA known as NSR. In January 2009, GenOn received an NOV from the EPA alleging that past work at Keystone, Portland and Shawville generating stations violated regulations regarding NSR. In June 2011, GenOn received an NOV from the EPA alleging that past work at Avon Lake and Niles generating stations violated NSR. In December 2007, the NJDEP filed suit alleging that NSR violations occurred at the Portland generating station. GenOn believes the suits are without merit and the subject work was conducted in compliance with applicable regulations. The Shawville, Niles and Portland generating units that are the subject of the NOVs are scheduled for retirement soon.

In 2008, the PADEP issued an NOV related to the inactive Monarch mine where low-volume wastewater from GenOn's Cheswick Generating Station and ash leachate was historically disposed. Resolution of the NOV could result in operational requirements such as pumping a minimum volume of water from the mine and a penalty in excess of $100,000.

The MDE sued GenOn Mid-Atlantic and GenOn MD Ash Management for alleged violations of water pollution laws at three fly ash disposal sites in Maryland: Faulkner (2008/2011), Brandywine (2010) and Westland (2012). On April 30, 2013, the court approved the consent decree resolving these issues. GenOn MD Ash Management has since discontinued use of the Faulkner disposal site and opened a new, state of the art carbon burnout facility at the Morgantown plant that allows greater beneficial reuse (as a cement substitute).

For further discussion of these matters, refer to Note 10, Commitments and Contingencies.

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Income Taxes

6 Months Ended

Jun. 30, 2013

Income Tax Disclosure [Abstract]

Income Taxes (GenOn, GenOn Americas Generation, GenOn Mid-Atlantic)

Income Taxes (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic)

GenOn

GenOn’s income tax (benefit)/expense consisted of the following:

	Successor		Predecessor		Successor		Predecessor
(In millions except otherwise noted)	Three months ended June 30, 2013		Three months ended June 30, 2012		Six months ended June 30, 2013		Six months ended June 30, 2012
Income/(loss) before income taxes	79		(224	)	(154	)	(256	)
Income tax (benefit)/expense	(6	)	4		(6	)	4
Effective tax rate	(7.59	)%	(1.79	)%	3.90	%	(1.56	)%

GenOn

For the three and six months ended June 30,2013 and 2012, GenOn's overall effective tax rate was different than the statutory rate of 35% primarily due to the recording of a valuation allowance against NOLs generated during the period.

Tax allocation — NRG will allocate taxes to GenOn Americas Generation and GenOn Mid-Atlantic, subsidiaries of GenOn using the pro rata method of income tax allocation as prescribed in ASC 740, Income Taxes. Electing to use the pro rata method requires presentation of a pro forma income statement for the most recent year and interim period reflecting a tax provision calculated on a separate return basis. Due to historical losses and the uncertainty surrounding the ability to generate future earnings, GenOn has recorded a full valuation allowance against its net deferred tax assets. Any change in the valuation allowance will be offset to the corresponding income tax expense or benefit. For the three and six months ended June 30, 2013 and 2012, GenOn recorded an income tax benefit and expense which relate to FIN 48 reserves for uncertain tax benefits.

GenOn Americas Generation

GenOn Americas Generation and most of its subsidiaries are limited liability companies that are treated as branches of NRG Americas for income tax purposes. As a result, NRG Americas, GenOn and NRG have direct liability for the majority of the federal and state income taxes relating to GenOn Americas Generation's operations. Several of GenOn Americas Generation's subsidiaries exist as regarded corporate entities for income tax purposes. For the subsidiaries that continue to exist as corporate regarded entities, GenOn Americas Generation allocates current and deferred income taxes to each corporate regarded entity as if such entity were a single taxpayer utilizing the asset and liability method to account for income taxes. To the extent GenOn Americas Generation provides tax expense or benefit, any related tax payable or receivable to NRG is reclassified to equity in the same period since GenOn Americas Generation does not have a tax sharing agreement with NRG.

GenOn Americas Generation would not be allocated income taxes attributable to its operations as of June 30,2013 and December 31, 2012, respectively as the income tax expense and benefit relate to FIN 48 reserves for uncertain tax benefits.

GenOn Mid-Atlantic

GenOn Mid-Atlantic and GenOn Mid-Atlantic's subsidiaries are limited liability companies that are treated as branches of NRG Americas for income tax purposes. As a result, NRG Americas, GenOn and NRG have direct liability for the majority of the federal and state income taxes relating to GenOn Mid-Atlantic's operations. If GenOn Mid-Atlantic were to be allocated income taxes attributable to its operations, the pro forma income tax provision attributable to income before taxes would be an expense of $23 million and tax benefit of $22 million during the three months ended June 30,2013 and 2012, respectively. The pro forma income tax provision attributable to income before taxes for the six months ended June 30, 2013 and 2012 would be a tax benefit of $4 million and tax expense of $6 million, respectively. The balance of GenOn Mid-Atlantic's pro forma deferred income taxes would be a net deferred tax asset of $603 million and $598 million as of June 30, 2013 and December 31, 2012, respectively.

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Accounting for Derivative Instruments and Hedging Activities (Tables)

6 Months Ended

Jun. 30, 2013

Accounting for Derivative Instruments and Hedging Activities

Net notional volume buy/(sell) of open derivative transactions broken out by commodity

The following table summarizes the net notional volume buy/(sell) of the Registrants’ open derivative transactions broken out by commodity, excluding those derivatives that qualified for the NPNS exception as of June 30, 2013 and December 31, 2012. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date.

		GenOn				GenOn Americas Generation				GenOn Mid-Atlantic
		Total Volume				Total Volume				Total Volume
		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012		As of June 30, 2013		As of December 31, 2012
Commodity	Units	(In millions)
Coal	Short Ton	7		5		4		4		4		4
Natural Gas	MMBtu	(163)		(194)		(121)		(150)		(121)		(150)
Power	MWh	(33)		(43)		(19)		(22)		(19)		(22)
Interest	Dollars	$	500	$	475	$	—	$	—	$	—	$	—

Fair value within the derivative instrument valuation on the balance sheets

The following tables summarize the fair value within the derivative instrument valuation on the balance sheet:

GenOn

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Designated as Cash Flow Hedges:
Interest rate contracts current	$	—	$	—	$	14	$	9
Interest rate contracts long-term	—		—		19		41
Total Derivatives Designated as Cash Flow Hedges	—		—		33		50
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	523		604		174		236
Commodity contracts long-term	343		512		53		83
Total Derivatives Not Designated as Cash Flow Hedges	866		1,116		227		319
Total Derivatives	$	866	$	1,116	$	260	$	369

Offsetting of derivatives by counterparty master agreement level and collateral received or paid

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	9			(9		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(9		)	9			—			—
Total commodity contracts	797			—			(242		)	555
Interest rate contracts:
Derivative liabilities	(50		)	—			—			(50		)
Total derivative instruments	$	747		$	—		$	(242	)	$	505

GenOn

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	860		$	(191	)	$	(219	)	$	450
Derivative assets - affiliate	6			(6		)	—			—
Derivative liabilities	(214		)	191			—			(23		)
Derivative liabilities - affiliate	(13		)	6			—			(7		)
Total commodity contracts	639			—			(219		)	420
Interest rate contracts:
Derivative liabilities	(33		)	—			—			(33		)
Total interest rate contracts	(33		)	—			—			(33		)
Total derivative instruments	$	606		$	—		$	(219	)	$	387

Effects of ASC 815 on accumulated OCI balance attributable to cash flow hedge derivatives, net of tax

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Accumulated OCI balance, beginning of period	$	2		$	(30	)	$	1		$	(34	)
Recognized in OCI on interest rate derivatives	17			(15		)	19			(11		)
Reclassified from accumulated OCI into earnings(a)(b)	(1		)	(1		)	(2		)	(1		)
Accumulated OCI balance, end of period	$	18		$	(46	)	$	18		$	(46	)

(a) Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded in interest expense.

(b) All of the forecasted transactions (future interest payments) were deemed probable of occurring; therefore, no cash flow hedges were discontinued and no amount was recognized in GenOn’s results of operations as a result of discontinued cash flow hedges

Pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the statements of operations

The following tables summarize the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Registrants’ statements of operations. These amounts are included within operating revenues and cost of operations.

GenOn

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(99	)	$	(99	)	$	(197	)	$	(228	)
Net unrealized gains/(losses) on open positions related to economic hedges	161			(54		)	38			182
Total unrealized mark-to-market gains/(losses) for economic hedging activities	62			(153		)	(159		)	(46		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	63		$	(142	)	$	(159	)	$	(42	)

	Successor		Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013		Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	45	$	(102	)	$	(190	)	$	41
Cost of operations	18		(40		)	31			(83		)
Total impact to statements of operations	$	63	$	(142	)	$	(159	)	$	(42	)

GenOn Americas Generation

Accounting for Derivative Instruments and Hedging Activities

Fair value within the derivative instrument valuation on the balance sheets

GenOn Americas Generation

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	594	$	656	$	287	$	362
Commodity contracts long-term	358		536		90		133
Total Derivatives Not Designated as Cash Flow Hedges	$	952	$	1,192	$	377	$	495

Offsetting of derivatives by counterparty master agreement level and collateral received or paid

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	859		$	(191	)	$	(219	)	$	449
Derivative assets - affiliate	93			(93		)	—			—
Derivative liabilities	(212		)	191			—			(21		)
Derivative liabilities - affiliate	(165		)	93			—			(72		)
Total derivative instruments	$	575		$	—		$	(219	)	$	356

GenOn Americas Generation

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	1,107		$	(260	)	$	(243	)	$	604
Derivative assets - affiliate	85			(85		)	—			—
Derivative liabilities	(310		)	260			1			(49		)
Derivative liabilities - affiliate	(185		)	85			—			(100		)
Total derivative instruments	$	697		$	—		$	(242	)	$	455

Pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the statements of operations

GenOn Americas Generation

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(75	)	$	(73	)	$	(149	)	$	(173	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(46		)	26			110
Total unrealized mark-to-market gains/(losses) for economic hedging activities	11			(119		)	(123		)	(63		)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	1			5			(2		)	2
Net unrealized gains on open positions related to trading activity	—			6			2			2
Total unrealized mark-to-market gains for trading activity	1			11			—			4
Total unrealized gains/(losses)	$	12		$	(108	)	$	(123	)	$	(59	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(2	)	$	(68	)	$	(153	)	$	7
Cost of operations	14			(40		)	30			(66		)
Total impact to statements of operations	$	12		$	(108	)	$	(123	)	$	(59	)

GenOn Mid-Atlantic

Accounting for Derivative Instruments and Hedging Activities

Fair value within the derivative instrument valuation on the balance sheets

GenOn Mid-Atlantic

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
	(In millions)
Derivatives Not Designated as Cash Flow Hedges:
Commodity contracts current	$	378	$	394	$	73	$	100
Commodity contracts long-term	303		455		35		55
Total Derivatives Not Designated as Cash Flow Hedges	$	681	$	849	$	108	$	155

Offsetting of derivatives by counterparty master agreement level and collateral received or paid

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
June 30, 2013	(In millions)
Commodity contracts:
Derivative assets	$	510		$	(5	)	$	(75	)	$	430
Derivative assets - affiliate	171			(103		)	—			68
Derivative liabilities	(5		)	5			—			—
Derivative liabilities - affiliate	(103		)	103			—			—
Total derivative instruments	$	573		$	—		$	(75	)	$	498

GenOn Mid-Atlantic

	Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
December 31, 2012	(In millions)
Commodity contracts:
Derivative assets	$	636		$	(3	)	$	(57	)	$	576
Derivative assets - affiliate	213			(152		)	—			61
Derivative liabilities	(3		)	3			—			—
Derivative liabilities - affiliate	(152		)	152			—			—
Total derivative instruments	$	694		$	—		$	(57	)	$	637

Pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the statements of operations

GenOn Mid-Atlantic

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$	(76	)	$	(73	)	$	(150	)	$	(175	)
Net unrealized gains/(losses) on open positions related to economic hedges	86			(40		)	28			104
Total unrealized gains/(losses)	$	10		$	(113	)	$	(122	)	$	(71	)

	Successor			Predecessor			Successor			Predecessor
(In millions)	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
Revenue from operations — energy commodities	$	(4	)	$	(66	)	$	(152	)	$	1
Cost of operations	14			(47		)	30			(72		)
Total impact to statements of operations	$	10		$	(113	)	$	(122	)	$	(71	)

XML

NRG Merger (Tables)

6 Months Ended

Jun. 30, 2013

NRG Merger

Schedule of provisional allocation of assets and liabilities

GenOn

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	983	$	—		$	983	$	—		$	983
Other current and non-current assets	2,049		(664		)	1,385		(18		)	1,367
Property, plant and equipment	6,286		(2,350		)	3,936		(27		)	3,909
Derivative assets	1,143		14			1,157		—			1,157
Deferred income taxes	220		—			220		—			220
Total assets	$	10,681	$	(3,000	)	$	7,681	$	(45	)	$	7,636
Liabilities
Other current and non-current liabilities	$	1,299	$	13		1,312		$	10		$	1,322
Out-of-market contracts and leases	331		733			1,064		15			1,079
Derivative liabilities	414		(15		)	399		—			399
Deferred income taxes	220		—			220		—			220
Long-term debt and capital leases	3,725		478			4,203		3			4,206
Total liabilities	$	5,989	$	1,209		$	7,198	$	28		$	7,226
Net assets	$	4,692	$	(4,209	)	$	483	$	(73	)	$	410

GenOn Americas Generation

NRG Merger

Schedule of provisional allocation of assets and liabilities

GenOn Americas Generation

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	171	$	—		$	171	$	—		$	171
Other current and non-current assets	1,509		(531		)	978		(14		)	964
Property, plant and equipment	2,875		(1,546		)	1,329		(60		)	1,269
Derivative assets	1,226		12			1,238		—			1,238
Total assets	$	5,781	$	(2,065	)	$	3,716	$	(74	)	$	3,642
Liabilities
Other current and non-current liabilities	$	705	$	(34	)	$	671	$	—		$	671
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	539		(10		)	529		—			529
Long-term debt and capital leases	862		99			961		—			961
Total liabilities	$	2,106	$	595		$	2,701	$	15		$	2,716
Net assets	$	3,675	$	(2,660	)	$	1,015	$	(89	)	$	926

GenOn Mid-Atlantic

NRG Merger

Schedule of provisional allocation of assets and liabilities

GenOn Mid-Atlantic

	Historical carrying amount		Acquisition accounting adjustment			Acquisition-date fair value as reported in 2012 10-K		Measurement period adjustments			Revised acquisition-date fair value
	(In millions)
Assets
Cash	$	163	$	—		$	163	$	—		$	163
Other current and non-current assets	700		(502		)	198		(12		)	186
Property, plant and equipment	2,399		(1,178		)	1,221		(110		)	1,111
Derivative assets	851		12			863		—			863
Total assets	$	4,113	$	(1,668	)	$	2,445	$	(122	)	$	2,323
Liabilities
Other current and non-current liabilities	$	198	$	6		$	204	—			$	204
Out-of-market contracts and leases	—		540			540		15			555
Derivative liabilities	172		(10		)	162		—			162
Long-term debt and capital leases	14		—			14		—			14
Total liabilities	$	384	$	536		$	920	$	15		$	935
Net assets	$	3,729	$	(2,204	)	$	1,525	$	(137	)	$	1,388

XML

Document and Entity Information	6 Months Ended
	Jun. 30, 2013
Entity Information
Entity Registrant Name	GenOn Energy, Inc.
Entity Central Index Key	0001126294
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Entity Common Stock, Shares Outstanding	1
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	Yes
Entity Current Reporting Status	Yes
GenOn Americas Generation
Entity Information
Entity Registrant Name	GenOn Americas Generation, LCC
Entity Central Index Key	0001140761
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Amendment Flag	false
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Entity Common Stock, Shares Outstanding	0
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	Yes
Entity Current Reporting Status	Yes
GenOn Mid-Atlantic
Entity Information
Entity Registrant Name	GenOn Mid-Atlantic, LLC
Entity Central Index Key	0001138258
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Amendment Flag	false
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Entity Common Stock, Shares Outstanding	0
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	Yes
Entity Current Reporting Status	Yes

XML

Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value of Financial Instruments

Estimated carrying amounts and fair values of recorded financial instruments not carried at fair market value

GenOn

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	3,649	$	3,545	$	4,185	$	4,195

Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis

GenOn

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn’s consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	127	$	722	$	17	$	866
Derivative liabilities:
Commodity contracts	$	44	$	169	$	14	$	227
Interest rate contracts	—		33		—		33
Total liabilities	$	44	$	202	$	14	$	260
Other assets (a)	$	44	$	—	$	—	$	44

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	139	$	946	$	31	$	1,116
Derivative liabilities:
Commodity contracts	$	52	$	253	$	14	$	319
Interest rate contracts	—		50		—		50
Total liabilities	$	52	$	303	$	14	$	369
Other assets (a)	$	43	$	—	$	—	$	43

(a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees.

Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs

The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for derivatives that are recognized at fair value in GenOn’s consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(36	)	$	17		$	(31	)
Total gains/(losses) included in earnings — realized/unrealized	3			(95		)	(16		)	(100		)
Purchases	6			—			2			—
Ending balance	$	3		$	(131	)	$	3		$	(131	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(131	)	$	1		$	(136	)

(a) Consists of derivative assets and liabilities, net.

Schedule of credit reserves for derivative contract assets

The Registrants' credit reserves were as follows:

	As of June 30, 2013			As of December 31, 2012
	(In millions)
GenOn	$	(3	)	$	(4	)
GenOn Americas Generation	$	(3	)	$	(4	)
GenOn Mid-Atlantic	$	(5	)	$	(4	)

Net counterparty credit exposure by industry sector and by counterparty credit quality

GenOn

Category	Net Exposure (a) (% of Total)
Financial institutions	60	%
Utilities, energy merchants, marketers and other	20	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a) Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Americas Generation

Fair Value of Financial Instruments

Estimated carrying amounts and fair values of recorded financial instruments not carried at fair market value

GenOn Americas Generation

	As of June 30, 2013				As of December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(In millions)
Long-term debt, including current portion	$	942	$	909	$	946	$	953

Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis

GenOn Americas Generation

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Americas Generation's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	149	$	784	$	19	$	952
Derivative liabilities:
Commodity contracts	$	103	$	258	$	16	$	377

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	170	$	991	$	31	$	1,192
Derivative liabilities:
Commodity contracts	$	123	$	358	$	14	$	495

Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs

The following tables reconcile, for the three and six months ended June 30, 2013 and 2012, the beginning and ending balances for GenOn Americas Generation's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(30	)	$	17		$	(32	)
Total gains/(losses) included in earnings — realized/unrealized	3			(83		)	(16		)	(81		)
Purchases	6			—			2			—
Ending balance	$	3		$	(113	)	$	3		$	(113	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	14		$	(121	)	$	1		$	(120	)

(a)    Consists of derivative assets and liabilities, net.

Net counterparty credit exposure by industry sector and by counterparty credit quality

GenOn Americas Generation

Category	Net Exposure (a) (% of Total)
Financial institutions	61	%
Utilities, energy merchants, marketers and other	19	%
ISOs	19	%
Coal	1	%
Total as of June 30, 2013	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	98	%
Non-rated	2	%
Total as of June 30, 2013	100	%

(a)    Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.

GenOn Mid-Atlantic

Fair Value of Financial Instruments

Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis

GenOn Mid-Atlantic

The following tables present assets and liabilities (including affiliate amounts) measured and recorded at fair value on GenOn Mid-Atlantic's consolidated balance sheet on a recurring basis and their level within the fair value hierarchy:

	As of June 30, 2013
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	68	$	609	$	4	$	681
Derivative liabilities:
Commodity contracts	$	20	$	86	$	2	$	108

	As of December 31, 2012
	Fair Value
	Level 1		Level 2		Level 3		Total
	(In millions)
Derivative assets:
Commodity contracts	$	63	$	778	$	8	$	849
Derivative liabilities:
Commodity contracts	$	16	$	138	$	1	$	155

Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs

The following tables reconcile, for the three and six months endedJune 30, 2013 and 2012, the beginning and ending balances for GenOn Mid-Atlantic's derivatives that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs:

	Fair Value Measurement Using Significant Unobservable Inputs (Level 3)
	Successor			Predecessor			Successor			Predecessor
	Three months ended June 30, 2013			Three months ended June 30, 2012			Six months ended June 30, 2013			Six months ended June 30, 2012
(In millions)	Derivatives (a)			Derivatives (a)			Derivatives (a)			Derivatives (a)
Beginning balance	$	(6	)	$	(88	)	$	7		$	(64	)
Total gains/(losses) included in earnings — realized/unrealized	2			(50		)	(7		)	(74		)
Purchases	6			—			2			—
Ending balance	$	2		$	(138	)	$	2		$	(138	)
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of June 30	$	8		$	(90	)	$	1		$	(115	)

(a) Consists of derivative assets and liabilities, net.

Net counterparty credit exposure by industry sector and by counterparty credit quality

GenOn Mid-Atlantic

Category	Net Exposure (a) (% of Total)
Financial institutions	100	%

Category	Net Exposure (a) (% of Total)
Investment grade	100	%

(a)Counterparty credit exposure excludes transportation contracts because of the unavailability of market prices.