Fair Value Measurements

6 Months Ended

Jun. 30, 2011

Fair Value Measurements

NOTE 7 - FAIR VALUE MEASUREMENTS

We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

See Note 8 - Fair Value Measurements under Part II, Item 8, of the Form 10-K for additional information of the definition of fair value and the fair value hierarchy.

In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. Ameren recorded losses totaling less than $1 million in the first six months of 2011 and gains totaling less than $1 million in the first six months of 2010 related to valuation adjustments for counterparty default risk. At June 30, 2011, the counterparty default risk valuation adjustment related to net derivative assets totaled $1 million and less than $1 million for Ameren and Genco, respectively. The counterparty default risk valuation adjustment related to net derivative liabilities totaled less than $1 million and $11 million for Ameren Missouri and Ameren Illinois, respectively. At December 31, 2010, the counterparty default risk valuation adjustment related to derivative contracts totaled $2 million, less than $1 million, $21 million, and less than $1 million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2011:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	72	$	72
	Natural gas		3		-		3		6
	Power		-		18		174		192
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		43		43
	Power		-		2		28		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		69		69
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		22		22
	Natural gas		1		-		-		1
	Power		-		-		4		4
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	4	$	4
	Natural gas		18		-		120		138
	Power		-		16		57		73
	Uranium		-		-		2		2
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		2		2
	Natural gas		9		-		11		20
	Power		-		1		3		4
	Uranium		-		-		2		2
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		5		-		108		113
	Power		-		-		273		273
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		1		1
	Natural gas		2		-		-		2
	Power		-		-		3		3

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2010:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	64	$	64
	Natural gas		3		-		2		5
	Power		-		17		86		103
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		37		37
	Natural gas		-		-		1		1
	Power		-		3		5		8
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		4		4
	Natural gas		2		-		-		2
	Power		-		-		8		8

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

In January 2010, the FASB issued amended authoritative guidance regarding fair value measurements. This guidance required disclosures regarding significant transfers into and out of Level 1 and Level 2 fair value measurements. It also required information on purchases, sales, issuances, and settlements on a gross basis in the reconciliation of Level 3 fair value measurements. This guidance was effective for us as of January 1, 2010, with the exception of guidance applicable to detailed Level 3 reconciliation disclosures, which became effective for us as of January 1, 2011. The adoption of this guidance did not have a material impact on our results of operations, financial position, or liquidity because it provides enhanced disclosure requirements only.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2011:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2011	$	96		$	57		$	(a	)	$	29		$	10
Realized and unrealized gains (losses):
Included in earnings(b)		(5	)		-			(a	)		(3	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(14	)		(9	)		(a	)		(3	)		(2	)
Purchases		1			1			(a	)		-			-
Settlements		(15	)		(8	)		(a	)		(5	)		(2	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(14	)	$	(8	)	$	(a	)	$	(4	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2011	$	(120	)	$	(12	)	$	(108	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(1	)		(19	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(20	)		(1	)		(19	)		-			-
Purchases		1			-			1			-			-
Settlements		22			2			20			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(18	)	$	(1	)	$	(17	)	$	-		$	-
Power:
Beginning balance at April 1, 2011	$	31		$	2		$	(325	)	$	3		$	351
Realized and unrealized gains (losses):
Included in earnings(b)		(15	)		-			-			(1	)		(14	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		66			(1	)		77			(a	)		(10	)
Total realized and unrealized gains (losses)		56			(1	)		77			(1	)		(19	)
Purchases		50			29			-			-			21
Sales		(7	)		-			-			-			(7	)
Settlements		(16	)		(6	)		44			(1	)		(53	)
Transfers into Level 3		1			-			-			-			1
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	(1	)	$	68		$	(1	)	$	(7	)
Uranium:
Beginning balance at April 1, 2011	$	1		$	1		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(3	)		(3	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2010:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2010	$	54		$	31		$	(a	)	$	18		$	5
Realized and unrealized gains (losses):
Included in earnings(b)		(8	)		-			(a	)		(6	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(17	)		(9	)		(a	)		(6	)		(2	)
Purchases		33			17			(a	)		11			5
Settlements		(41	)		(23	)		(a	)		(13	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(16	)	$	(9	)	$	(a	)	$	(5	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2010	$	(162	)	$	(18	)	$	(144	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(6	)		(1	)		(5	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(6	)		(1	)		(5	)		-			-
Purchases		-			-			-			-			-
Settlements		30			4			26			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(6	)	$	(1	)	$	(5	)	$	-		$	-
Power:
Beginning balance at April 1, 2010	$	37		$	5		$	(554	)	$	3		$	583
Realized and unrealized gains (losses):
Included in earnings(b)		6			-			-			-			6
Included in OCI		(18	)		-			-			-			(18	)
Included in regulatory assets/liabilities		29			1			98			(a	)		(70	)
Total realized and unrealized gains (losses)		17			1			98			-			(82	)
Purchases		25			5			17			(2	)		5
Sales		2			-			-			3			(1	)
Settlements		(19	)		(6	)		33			(1	)		(45	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(7	)		-			-			-			(7	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(5	)	$	(3	)	$	67		$	-		$	(69	)
Uranium:
Beginning balance at April 1, 2010	$	(3	)	$	(3	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(1	)		(1	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(1	)		(1	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2011:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2011	$	51		$	30		$	(a	)	$	17		$	4
Realized and unrealized gains (losses):
Included in earnings(b)		17			-			(a	)		12			5
Included in regulatory assets/liabilities		22			22			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		39			22			(a	)		12			5
Purchases		2			2			(a	)		-			-
Settlements		(24	)		(13	)		(a	)		(8	)		(3	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	30		$	18		$	(a	)	$	9		$	3
Natural gas:
Beginning balance at January 1, 2011	$	(148	)	$	(14	)	$	(134	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(13	)		(1	)		(12	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(13	)		(1	)		(12	)		-			-
Purchases		1			-			1			-			-
Settlements		43			4			39			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	9		$	1		$	8		$	-		$	-
Power:
Beginning balance at January 1, 2011	$	36		$	2		$	(352	)	$	3		$	383
Realized and unrealized gains (losses):
Included in earnings(b)		(18	)		-			-			(1	)		(17	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		64			6			47			(a	)		11
Total realized and unrealized gains (losses)		51			6			47			(1	)		(1	)
Purchases		59			29			-			-			30
Sales		(16	)		-			-			-			(16	)
Settlements		(16	)		(12	)		101			(1	)		(104	)
Transfers into Level 3		1			(1	)		-			-			2
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	-		$	64		$	(1	)	$	(4	)
Uranium:
Beginning balance at January 1, 2011	$	2		$	2		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(4	)		(4	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(4	)		(4	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2010:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2010	$	60		$	32		$	(a	)	$	21		$	7
Realized and unrealized gains (losses):
Included in earnings(b)		(10	)		-			(a	)		(8	)		(2	)
Included in regulatory assets/liabilities		(11	)		(11	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(21	)		(11	)		(a	)		(8	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(42	)		(23	)		(a	)		(14	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(18	)	$	(10	)	$	(a	)	$	(6	)	$	(2	)
Natural gas:
Beginning balance at January 1, 2010	$	(67	)	$	(6	)	$	(61	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(109	)		(14	)		(95	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(109	)		(14	)		(95	)		-			-
Purchases		(4	)		-			(4	)		-			-
Settlements		42			5			37			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(81	)	$	(10	)	$	(71	)	$	-		$	-
Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings(b)		24			-			-			2			22
Included in OCI		6			-			-			-			6
Included in regulatory assets/liabilities		7			13			(69	)		(a	)		63
Total realized and unrealized gains (losses)		37			13			(69	)		2			91
Purchases		38			4			17			(4	)		21
Sales		(5	)		1			-			5			(11	)
Settlements		(29	)		(9	)		68			(1	)		(87	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(24	)		(3	)		-			-			(21	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(7	)	$	1		$	(79	)	$	1		$	70
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(2	)		(2	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(2	)		(2	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

Transfers out of Level 3 represent existing assets and liabilities that were previously classified as Level 3 but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers into Level 3 represent existing assets and liabilities that were previously classified as a higher level but were recategorized to Level 3 because the lowest significant input became unobservable during the period. Transfers between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable in active markets compared with previous periods for the quarters ended June 30, 2011, and 2010. Any reclassifications are reported at the fair value measurement reported at the beginning of the period in which the changes occur. For the three and six months ended June 30, 2011, and 2010, there were no transfers into or out of Level 1.

The Ameren Companies' carrying amounts of cash and cash equivalents, accounts receivable, short-term borrowings, and accounts payable approximate fair value because of the short-term nature of these instruments. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments.

The following table presents the carrying amounts and estimated fair values of our long-term debt and capital lease obligations and preferred stock at June 30, 2011, and December 31, 2010:

	June 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,859	$	7,666	$	7,008	$	7,661
Preferred stock		142		102		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,954	$	4,378	$	3,954	$	4,281
Preferred stock		80		61		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,956	$	1,807	$	2,067
Preferred stock		62		41		62		40
Genco:
Long-term debt (including current portion)	$	824	$	843	$	824	$	826

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) Preferred stock not subject to mandatory redemption of the Ameren subsidiaries along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.

Ameren Illinois [Member]

Fair Value Measurements

NOTE 7 - FAIR VALUE MEASUREMENTS

We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

See Note 8 - Fair Value Measurements under Part II, Item 8, of the Form 10-K for additional information of the definition of fair value and the fair value hierarchy.

In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. Ameren recorded losses totaling less than $1 million in the first six months of 2011 and gains totaling less than $1 million in the first six months of 2010 related to valuation adjustments for counterparty default risk. At June 30, 2011, the counterparty default risk valuation adjustment related to net derivative assets totaled $1 million and less than $1 million for Ameren and Genco, respectively. The counterparty default risk valuation adjustment related to net derivative liabilities totaled less than $1 million and $11 million for Ameren Missouri and Ameren Illinois, respectively. At December 31, 2010, the counterparty default risk valuation adjustment related to derivative contracts totaled $2 million, less than $1 million, $21 million, and less than $1 million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2011:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	72	$	72
	Natural gas		3		-		3		6
	Power		-		18		174		192
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		43		43
	Power		-		2		28		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		69		69
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		22		22
	Natural gas		1		-		-		1
	Power		-		-		4		4
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	4	$	4
	Natural gas		18		-		120		138
	Power		-		16		57		73
	Uranium		-		-		2		2
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		2		2
	Natural gas		9		-		11		20
	Power		-		1		3		4
	Uranium		-		-		2		2
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		5		-		108		113
	Power		-		-		273		273
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		1		1
	Natural gas		2		-		-		2
	Power		-		-		3		3

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2010:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	64	$	64
	Natural gas		3		-		2		5
	Power		-		17		86		103
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		37		37
	Natural gas		-		-		1		1
	Power		-		3		5		8
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		4		4
	Natural gas		2		-		-		2
	Power		-		-		8		8

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

In January 2010, the FASB issued amended authoritative guidance regarding fair value measurements. This guidance required disclosures regarding significant transfers into and out of Level 1 and Level 2 fair value measurements. It also required information on purchases, sales, issuances, and settlements on a gross basis in the reconciliation of Level 3 fair value measurements. This guidance was effective for us as of January 1, 2010, with the exception of guidance applicable to detailed Level 3 reconciliation disclosures, which became effective for us as of January 1, 2011. The adoption of this guidance did not have a material impact on our results of operations, financial position, or liquidity because it provides enhanced disclosure requirements only.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2011:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2011	$	96		$	57		$	(a	)	$	29		$	10
Realized and unrealized gains (losses):
Included in earnings(b)		(5	)		-			(a	)		(3	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(14	)		(9	)		(a	)		(3	)		(2	)
Purchases		1			1			(a	)		-			-
Settlements		(15	)		(8	)		(a	)		(5	)		(2	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(14	)	$	(8	)	$	(a	)	$	(4	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2011	$	(120	)	$	(12	)	$	(108	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(1	)		(19	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(20	)		(1	)		(19	)		-			-
Purchases		1			-			1			-			-
Settlements		22			2			20			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(18	)	$	(1	)	$	(17	)	$	-		$	-
Power:
Beginning balance at April 1, 2011	$	31		$	2		$	(325	)	$	3		$	351
Realized and unrealized gains (losses):
Included in earnings(b)		(15	)		-			-			(1	)		(14	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		66			(1	)		77			(a	)		(10	)
Total realized and unrealized gains (losses)		56			(1	)		77			(1	)		(19	)
Purchases		50			29			-			-			21
Sales		(7	)		-			-			-			(7	)
Settlements		(16	)		(6	)		44			(1	)		(53	)
Transfers into Level 3		1			-			-			-			1
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	(1	)	$	68		$	(1	)	$	(7	)
Uranium:
Beginning balance at April 1, 2011	$	1		$	1		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(3	)		(3	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2010:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2010	$	54		$	31		$	(a	)	$	18		$	5
Realized and unrealized gains (losses):
Included in earnings(b)		(8	)		-			(a	)		(6	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(17	)		(9	)		(a	)		(6	)		(2	)
Purchases		33			17			(a	)		11			5
Settlements		(41	)		(23	)		(a	)		(13	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(16	)	$	(9	)	$	(a	)	$	(5	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2010	$	(162	)	$	(18	)	$	(144	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(6	)		(1	)		(5	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(6	)		(1	)		(5	)		-			-
Purchases		-			-			-			-			-
Settlements		30			4			26			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(6	)	$	(1	)	$	(5	)	$	-		$	-
Power:
Beginning balance at April 1, 2010	$	37		$	5		$	(554	)	$	3		$	583
Realized and unrealized gains (losses):
Included in earnings(b)		6			-			-			-			6
Included in OCI		(18	)		-			-			-			(18	)
Included in regulatory assets/liabilities		29			1			98			(a	)		(70	)
Total realized and unrealized gains (losses)		17			1			98			-			(82	)
Purchases		25			5			17			(2	)		5
Sales		2			-			-			3			(1	)
Settlements		(19	)		(6	)		33			(1	)		(45	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(7	)		-			-			-			(7	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(5	)	$	(3	)	$	67		$	-		$	(69	)
Uranium:
Beginning balance at April 1, 2010	$	(3	)	$	(3	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(1	)		(1	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(1	)		(1	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2011:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2011	$	51		$	30		$	(a	)	$	17		$	4
Realized and unrealized gains (losses):
Included in earnings(b)		17			-			(a	)		12			5
Included in regulatory assets/liabilities		22			22			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		39			22			(a	)		12			5
Purchases		2			2			(a	)		-			-
Settlements		(24	)		(13	)		(a	)		(8	)		(3	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	30		$	18		$	(a	)	$	9		$	3
Natural gas:
Beginning balance at January 1, 2011	$	(148	)	$	(14	)	$	(134	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(13	)		(1	)		(12	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(13	)		(1	)		(12	)		-			-
Purchases		1			-			1			-			-
Settlements		43			4			39			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	9		$	1		$	8		$	-		$	-
Power:
Beginning balance at January 1, 2011	$	36		$	2		$	(352	)	$	3		$	383
Realized and unrealized gains (losses):
Included in earnings(b)		(18	)		-			-			(1	)		(17	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		64			6			47			(a	)		11
Total realized and unrealized gains (losses)		51			6			47			(1	)		(1	)
Purchases		59			29			-			-			30
Sales		(16	)		-			-			-			(16	)
Settlements		(16	)		(12	)		101			(1	)		(104	)
Transfers into Level 3		1			(1	)		-			-			2
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	-		$	64		$	(1	)	$	(4	)
Uranium:
Beginning balance at January 1, 2011	$	2		$	2		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(4	)		(4	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(4	)		(4	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2010:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2010	$	60		$	32		$	(a	)	$	21		$	7
Realized and unrealized gains (losses):
Included in earnings(b)		(10	)		-			(a	)		(8	)		(2	)
Included in regulatory assets/liabilities		(11	)		(11	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(21	)		(11	)		(a	)		(8	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(42	)		(23	)		(a	)		(14	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(18	)	$	(10	)	$	(a	)	$	(6	)	$	(2	)
Natural gas:
Beginning balance at January 1, 2010	$	(67	)	$	(6	)	$	(61	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(109	)		(14	)		(95	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(109	)		(14	)		(95	)		-			-
Purchases		(4	)		-			(4	)		-			-
Settlements		42			5			37			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(81	)	$	(10	)	$	(71	)	$	-		$	-
Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings(b)		24			-			-			2			22
Included in OCI		6			-			-			-			6
Included in regulatory assets/liabilities		7			13			(69	)		(a	)		63
Total realized and unrealized gains (losses)		37			13			(69	)		2			91
Purchases		38			4			17			(4	)		21
Sales		(5	)		1			-			5			(11	)
Settlements		(29	)		(9	)		68			(1	)		(87	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(24	)		(3	)		-			-			(21	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(7	)	$	1		$	(79	)	$	1		$	70
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(2	)		(2	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(2	)		(2	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

Transfers out of Level 3 represent existing assets and liabilities that were previously classified as Level 3 but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers into Level 3 represent existing assets and liabilities that were previously classified as a higher level but were recategorized to Level 3 because the lowest significant input became unobservable during the period. Transfers between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable in active markets compared with previous periods for the quarters ended June 30, 2011, and 2010. Any reclassifications are reported at the fair value measurement reported at the beginning of the period in which the changes occur. For the three and six months ended June 30, 2011, and 2010, there were no transfers into or out of Level 1.

The Ameren Companies' carrying amounts of cash and cash equivalents, accounts receivable, short-term borrowings, and accounts payable approximate fair value because of the short-term nature of these instruments. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments.

The following table presents the carrying amounts and estimated fair values of our long-term debt and capital lease obligations and preferred stock at June 30, 2011, and December 31, 2010:

	June 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,859	$	7,666	$	7,008	$	7,661
Preferred stock		142		102		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,954	$	4,378	$	3,954	$	4,281
Preferred stock		80		61		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,956	$	1,807	$	2,067
Preferred stock		62		41		62		40
Genco:
Long-term debt (including current portion)	$	824	$	843	$	824	$	826

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) Preferred stock not subject to mandatory redemption of the Ameren subsidiaries along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.

Ameren Energy Generating Company [Member]

Fair Value Measurements

NOTE 7 - FAIR VALUE MEASUREMENTS

We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

See Note 8 - Fair Value Measurements under Part II, Item 8, of the Form 10-K for additional information of the definition of fair value and the fair value hierarchy.

In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. Ameren recorded losses totaling less than $1 million in the first six months of 2011 and gains totaling less than $1 million in the first six months of 2010 related to valuation adjustments for counterparty default risk. At June 30, 2011, the counterparty default risk valuation adjustment related to net derivative assets totaled $1 million and less than $1 million for Ameren and Genco, respectively. The counterparty default risk valuation adjustment related to net derivative liabilities totaled less than $1 million and $11 million for Ameren Missouri and Ameren Illinois, respectively. At December 31, 2010, the counterparty default risk valuation adjustment related to derivative contracts totaled $2 million, less than $1 million, $21 million, and less than $1 million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2011:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	72	$	72
	Natural gas		3		-		3		6
	Power		-		18		174		192
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		43		43
	Power		-		2		28		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		69		69
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		22		22
	Natural gas		1		-		-		1
	Power		-		-		4		4
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	4	$	4
	Natural gas		18		-		120		138
	Power		-		16		57		73
	Uranium		-		-		2		2
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		2		2
	Natural gas		9		-		11		20
	Power		-		1		3		4
	Uranium		-		-		2		2
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		5		-		108		113
	Power		-		-		273		273
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		1		1
	Natural gas		2		-		-		2
	Power		-		-		3		3

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2010:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	64	$	64
	Natural gas		3		-		2		5
	Power		-		17		86		103
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		37		37
	Natural gas		-		-		1		1
	Power		-		3		5		8
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		4		4
	Natural gas		2		-		-		2
	Power		-		-		8		8

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

In January 2010, the FASB issued amended authoritative guidance regarding fair value measurements. This guidance required disclosures regarding significant transfers into and out of Level 1 and Level 2 fair value measurements. It also required information on purchases, sales, issuances, and settlements on a gross basis in the reconciliation of Level 3 fair value measurements. This guidance was effective for us as of January 1, 2010, with the exception of guidance applicable to detailed Level 3 reconciliation disclosures, which became effective for us as of January 1, 2011. The adoption of this guidance did not have a material impact on our results of operations, financial position, or liquidity because it provides enhanced disclosure requirements only.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2011:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2011	$	96		$	57		$	(a	)	$	29		$	10
Realized and unrealized gains (losses):
Included in earnings(b)		(5	)		-			(a	)		(3	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(14	)		(9	)		(a	)		(3	)		(2	)
Purchases		1			1			(a	)		-			-
Settlements		(15	)		(8	)		(a	)		(5	)		(2	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(14	)	$	(8	)	$	(a	)	$	(4	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2011	$	(120	)	$	(12	)	$	(108	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(1	)		(19	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(20	)		(1	)		(19	)		-			-
Purchases		1			-			1			-			-
Settlements		22			2			20			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(18	)	$	(1	)	$	(17	)	$	-		$	-
Power:
Beginning balance at April 1, 2011	$	31		$	2		$	(325	)	$	3		$	351
Realized and unrealized gains (losses):
Included in earnings(b)		(15	)		-			-			(1	)		(14	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		66			(1	)		77			(a	)		(10	)
Total realized and unrealized gains (losses)		56			(1	)		77			(1	)		(19	)
Purchases		50			29			-			-			21
Sales		(7	)		-			-			-			(7	)
Settlements		(16	)		(6	)		44			(1	)		(53	)
Transfers into Level 3		1			-			-			-			1
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	(1	)	$	68		$	(1	)	$	(7	)
Uranium:
Beginning balance at April 1, 2011	$	1		$	1		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(3	)		(3	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2010:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2010	$	54		$	31		$	(a	)	$	18		$	5
Realized and unrealized gains (losses):
Included in earnings(b)		(8	)		-			(a	)		(6	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(17	)		(9	)		(a	)		(6	)		(2	)
Purchases		33			17			(a	)		11			5
Settlements		(41	)		(23	)		(a	)		(13	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(16	)	$	(9	)	$	(a	)	$	(5	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2010	$	(162	)	$	(18	)	$	(144	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(6	)		(1	)		(5	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(6	)		(1	)		(5	)		-			-
Purchases		-			-			-			-			-
Settlements		30			4			26			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(6	)	$	(1	)	$	(5	)	$	-		$	-
Power:
Beginning balance at April 1, 2010	$	37		$	5		$	(554	)	$	3		$	583
Realized and unrealized gains (losses):
Included in earnings(b)		6			-			-			-			6
Included in OCI		(18	)		-			-			-			(18	)
Included in regulatory assets/liabilities		29			1			98			(a	)		(70	)
Total realized and unrealized gains (losses)		17			1			98			-			(82	)
Purchases		25			5			17			(2	)		5
Sales		2			-			-			3			(1	)
Settlements		(19	)		(6	)		33			(1	)		(45	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(7	)		-			-			-			(7	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(5	)	$	(3	)	$	67		$	-		$	(69	)
Uranium:
Beginning balance at April 1, 2010	$	(3	)	$	(3	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(1	)		(1	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(1	)		(1	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2011:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2011	$	51		$	30		$	(a	)	$	17		$	4
Realized and unrealized gains (losses):
Included in earnings(b)		17			-			(a	)		12			5
Included in regulatory assets/liabilities		22			22			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		39			22			(a	)		12			5
Purchases		2			2			(a	)		-			-
Settlements		(24	)		(13	)		(a	)		(8	)		(3	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	30		$	18		$	(a	)	$	9		$	3
Natural gas:
Beginning balance at January 1, 2011	$	(148	)	$	(14	)	$	(134	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(13	)		(1	)		(12	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(13	)		(1	)		(12	)		-			-
Purchases		1			-			1			-			-
Settlements		43			4			39			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	9		$	1		$	8		$	-		$	-
Power:
Beginning balance at January 1, 2011	$	36		$	2		$	(352	)	$	3		$	383
Realized and unrealized gains (losses):
Included in earnings(b)		(18	)		-			-			(1	)		(17	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		64			6			47			(a	)		11
Total realized and unrealized gains (losses)		51			6			47			(1	)		(1	)
Purchases		59			29			-			-			30
Sales		(16	)		-			-			-			(16	)
Settlements		(16	)		(12	)		101			(1	)		(104	)
Transfers into Level 3		1			(1	)		-			-			2
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	-		$	64		$	(1	)	$	(4	)
Uranium:
Beginning balance at January 1, 2011	$	2		$	2		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(4	)		(4	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(4	)		(4	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2010:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2010	$	60		$	32		$	(a	)	$	21		$	7
Realized and unrealized gains (losses):
Included in earnings(b)		(10	)		-			(a	)		(8	)		(2	)
Included in regulatory assets/liabilities		(11	)		(11	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(21	)		(11	)		(a	)		(8	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(42	)		(23	)		(a	)		(14	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(18	)	$	(10	)	$	(a	)	$	(6	)	$	(2	)
Natural gas:
Beginning balance at January 1, 2010	$	(67	)	$	(6	)	$	(61	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(109	)		(14	)		(95	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(109	)		(14	)		(95	)		-			-
Purchases		(4	)		-			(4	)		-			-
Settlements		42			5			37			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(81	)	$	(10	)	$	(71	)	$	-		$	-
Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings(b)		24			-			-			2			22
Included in OCI		6			-			-			-			6
Included in regulatory assets/liabilities		7			13			(69	)		(a	)		63
Total realized and unrealized gains (losses)		37			13			(69	)		2			91
Purchases		38			4			17			(4	)		21
Sales		(5	)		1			-			5			(11	)
Settlements		(29	)		(9	)		68			(1	)		(87	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(24	)		(3	)		-			-			(21	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(7	)	$	1		$	(79	)	$	1		$	70
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(2	)		(2	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(2	)		(2	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

Transfers out of Level 3 represent existing assets and liabilities that were previously classified as Level 3 but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers into Level 3 represent existing assets and liabilities that were previously classified as a higher level but were recategorized to Level 3 because the lowest significant input became unobservable during the period. Transfers between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable in active markets compared with previous periods for the quarters ended June 30, 2011, and 2010. Any reclassifications are reported at the fair value measurement reported at the beginning of the period in which the changes occur. For the three and six months ended June 30, 2011, and 2010, there were no transfers into or out of Level 1.

The Ameren Companies' carrying amounts of cash and cash equivalents, accounts receivable, short-term borrowings, and accounts payable approximate fair value because of the short-term nature of these instruments. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments.

The following table presents the carrying amounts and estimated fair values of our long-term debt and capital lease obligations and preferred stock at June 30, 2011, and December 31, 2010:

	June 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,859	$	7,666	$	7,008	$	7,661
Preferred stock		142		102		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,954	$	4,378	$	3,954	$	4,281
Preferred stock		80		61		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,956	$	1,807	$	2,067
Preferred stock		62		41		62		40
Genco:
Long-term debt (including current portion)	$	824	$	843	$	824	$	826

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) Preferred stock not subject to mandatory redemption of the Ameren subsidiaries along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.

Union Electric Company [Member]

Fair Value Measurements

NOTE 7 - FAIR VALUE MEASUREMENTS

We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

See Note 8 - Fair Value Measurements under Part II, Item 8, of the Form 10-K for additional information of the definition of fair value and the fair value hierarchy.

In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. Ameren recorded losses totaling less than $1 million in the first six months of 2011 and gains totaling less than $1 million in the first six months of 2010 related to valuation adjustments for counterparty default risk. At June 30, 2011, the counterparty default risk valuation adjustment related to net derivative assets totaled $1 million and less than $1 million for Ameren and Genco, respectively. The counterparty default risk valuation adjustment related to net derivative liabilities totaled less than $1 million and $11 million for Ameren Missouri and Ameren Illinois, respectively. At December 31, 2010, the counterparty default risk valuation adjustment related to derivative contracts totaled $2 million, less than $1 million, $21 million, and less than $1 million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2011:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	72	$	72
	Natural gas		3		-		3		6
	Power		-		18		174		192
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		43		43
	Power		-		2		28		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		69		69
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		22		22
	Natural gas		1		-		-		1
	Power		-		-		4		4
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	4	$	4
	Natural gas		18		-		120		138
	Power		-		16		57		73
	Uranium		-		-		2		2
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		2		2
	Natural gas		9		-		11		20
	Power		-		1		3		4
	Uranium		-		-		2		2
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		5		-		108		113
	Power		-		-		273		273
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		1		1
	Natural gas		2		-		-		2
	Power		-		-		3		3

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2010:

		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren(a)	Derivative assets - commodity contracts(b):
	Heating oil	$	-	$	-	$	64	$	64
	Natural gas		3		-		2		5
	Power		-		17		86		103
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		37		37
	Natural gas		-		-		1		1
	Power		-		3		5		8
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		4		4
	Natural gas		2		-		-		2
	Power		-		-		8		8

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) The derivative asset and liability balances are presented net of counterparty credit considerations.

(c) Balance excludes $1 million of receivables, payables, and accrued income, net.

In January 2010, the FASB issued amended authoritative guidance regarding fair value measurements. This guidance required disclosures regarding significant transfers into and out of Level 1 and Level 2 fair value measurements. It also required information on purchases, sales, issuances, and settlements on a gross basis in the reconciliation of Level 3 fair value measurements. This guidance was effective for us as of January 1, 2010, with the exception of guidance applicable to detailed Level 3 reconciliation disclosures, which became effective for us as of January 1, 2011. The adoption of this guidance did not have a material impact on our results of operations, financial position, or liquidity because it provides enhanced disclosure requirements only.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2011:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2011	$	96		$	57		$	(a	)	$	29		$	10
Realized and unrealized gains (losses):
Included in earnings(b)		(5	)		-			(a	)		(3	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(14	)		(9	)		(a	)		(3	)		(2	)
Purchases		1			1			(a	)		-			-
Settlements		(15	)		(8	)		(a	)		(5	)		(2	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(14	)	$	(8	)	$	(a	)	$	(4	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2011	$	(120	)	$	(12	)	$	(108	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(1	)		(19	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(20	)		(1	)		(19	)		-			-
Purchases		1			-			1			-			-
Settlements		22			2			20			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(18	)	$	(1	)	$	(17	)	$	-		$	-
Power:
Beginning balance at April 1, 2011	$	31		$	2		$	(325	)	$	3		$	351
Realized and unrealized gains (losses):
Included in earnings(b)		(15	)		-			-			(1	)		(14	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		66			(1	)		77			(a	)		(10	)
Total realized and unrealized gains (losses)		56			(1	)		77			(1	)		(19	)
Purchases		50			29			-			-			21
Sales		(7	)		-			-			-			(7	)
Settlements		(16	)		(6	)		44			(1	)		(53	)
Transfers into Level 3		1			-			-			-			1
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	(1	)	$	68		$	(1	)	$	(7	)
Uranium:
Beginning balance at April 1, 2011	$	1		$	1		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(3	)		(3	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2010:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2010	$	54		$	31		$	(a	)	$	18		$	5
Realized and unrealized gains (losses):
Included in earnings(b)		(8	)		-			(a	)		(6	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(17	)		(9	)		(a	)		(6	)		(2	)
Purchases		33			17			(a	)		11			5
Settlements		(41	)		(23	)		(a	)		(13	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(16	)	$	(9	)	$	(a	)	$	(5	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2010	$	(162	)	$	(18	)	$	(144	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(6	)		(1	)		(5	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(6	)		(1	)		(5	)		-			-
Purchases		-			-			-			-			-
Settlements		30			4			26			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(6	)	$	(1	)	$	(5	)	$	-		$	-
Power:
Beginning balance at April 1, 2010	$	37		$	5		$	(554	)	$	3		$	583
Realized and unrealized gains (losses):
Included in earnings(b)		6			-			-			-			6
Included in OCI		(18	)		-			-			-			(18	)
Included in regulatory assets/liabilities		29			1			98			(a	)		(70	)
Total realized and unrealized gains (losses)		17			1			98			-			(82	)
Purchases		25			5			17			(2	)		5
Sales		2			-			-			3			(1	)
Settlements		(19	)		(6	)		33			(1	)		(45	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(7	)		-			-			-			(7	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(5	)	$	(3	)	$	67		$	-		$	(69	)
Uranium:
Beginning balance at April 1, 2010	$	(3	)	$	(3	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(1	)		(1	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(1	)		(1	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2011:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2011	$	51		$	30		$	(a	)	$	17		$	4
Realized and unrealized gains (losses):
Included in earnings(b)		17			-			(a	)		12			5
Included in regulatory assets/liabilities		22			22			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		39			22			(a	)		12			5
Purchases		2			2			(a	)		-			-
Settlements		(24	)		(13	)		(a	)		(8	)		(3	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	30		$	18		$	(a	)	$	9		$	3
Natural gas:
Beginning balance at January 1, 2011	$	(148	)	$	(14	)	$	(134	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(13	)		(1	)		(12	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(13	)		(1	)		(12	)		-			-
Purchases		1			-			1			-			-
Settlements		43			4			39			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	9		$	1		$	8		$	-		$	-
Power:
Beginning balance at January 1, 2011	$	36		$	2		$	(352	)	$	3		$	383
Realized and unrealized gains (losses):
Included in earnings(b)		(18	)		-			-			(1	)		(17	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		64			6			47			(a	)		11
Total realized and unrealized gains (losses)		51			6			47			(1	)		(1	)
Purchases		59			29			-			-			30
Sales		(16	)		-			-			-			(16	)
Settlements		(16	)		(12	)		101			(1	)		(104	)
Transfers into Level 3		1			(1	)		-			-			2
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	-		$	64		$	(1	)	$	(4	)
Uranium:
Beginning balance at January 1, 2011	$	2		$	2		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(4	)		(4	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(4	)		(4	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2010:

	Net derivative commodity contracts
Six Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at January 1, 2010	$	60		$	32		$	(a	)	$	21		$	7
Realized and unrealized gains (losses):
Included in earnings(b)		(10	)		-			(a	)		(8	)		(2	)
Included in regulatory assets/liabilities		(11	)		(11	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(21	)		(11	)		(a	)		(8	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(42	)		(23	)		(a	)		(14	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(18	)	$	(10	)	$	(a	)	$	(6	)	$	(2	)
Natural gas:
Beginning balance at January 1, 2010	$	(67	)	$	(6	)	$	(61	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(109	)		(14	)		(95	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(109	)		(14	)		(95	)		-			-
Purchases		(4	)		-			(4	)		-			-
Settlements		42			5			37			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(81	)	$	(10	)	$	(71	)	$	-		$	-
Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings(b)		24			-			-			2			22
Included in OCI		6			-			-			-			6
Included in regulatory assets/liabilities		7			13			(69	)		(a	)		63
Total realized and unrealized gains (losses)		37			13			(69	)		2			91
Purchases		38			4			17			(4	)		21
Sales		(5	)		1			-			5			(11	)
Settlements		(29	)		(9	)		68			(1	)		(87	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(24	)		(3	)		-			-			(21	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(7	)	$	1		$	(79	)	$	1		$	70
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(2	)		(2	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(2	)		(2	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

(a) Not applicable.

(b) Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c) Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

Transfers out of Level 3 represent existing assets and liabilities that were previously classified as Level 3 but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers into Level 3 represent existing assets and liabilities that were previously classified as a higher level but were recategorized to Level 3 because the lowest significant input became unobservable during the period. Transfers between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable in active markets compared with previous periods for the quarters ended June 30, 2011, and 2010. Any reclassifications are reported at the fair value measurement reported at the beginning of the period in which the changes occur. For the three and six months ended June 30, 2011, and 2010, there were no transfers into or out of Level 1.

The Ameren Companies' carrying amounts of cash and cash equivalents, accounts receivable, short-term borrowings, and accounts payable approximate fair value because of the short-term nature of these instruments. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments.

The following table presents the carrying amounts and estimated fair values of our long-term debt and capital lease obligations and preferred stock at June 30, 2011, and December 31, 2010:

	June 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,859	$	7,666	$	7,008	$	7,661
Preferred stock		142		102		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,954	$	4,378	$	3,954	$	4,281
Preferred stock		80		61		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,956	$	1,807	$	2,067
Preferred stock		62		41		62		40
Genco:
Long-term debt (including current portion)	$	824	$	843	$	824	$	826

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b) Preferred stock not subject to mandatory redemption of the Ameren subsidiaries along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.