Fair Value Measurements

12 Months Ended

Dec. 31, 2011

Fair Value Measurements

NOTE 8 – FAIR VALUE MEASUREMENTS

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:

Level 1: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri's Nuclear Decommissioning Trust Fund.

Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri's Nuclear Decommissioning Trust Fund, including corporate bonds and other fixed-income securities, U.S. treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas swaps and financial power transactions. Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints of the bid/ask spreads. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint.

Level 3: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable, including the financial contracts entered into between Ameren Illinois and Marketing Company. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as well as certain internal assumptions. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a part of our reasonableness review, an evaluation of all sources is performed to identify any anomalies or potential errors.

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.

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 net losses of $2 million, net gains of less than $1 million, and net losses of less than $1 million in 2011, 2010 and 2009, respectively, related to valuation adjustments for counterparty default risk. Genco recorded net losses of less than $1 million, net gains of less than $1 million, and net gains of less than $1 million in 2011, 2010, and 2009, respectively, related to valuation adjustments for counterparty default risk. At December 31, 2011, the counterparty default risk (asset)/liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, $19 million, and less than $(1) million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively. At December 31, 2010, the counterparty default risk liability 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 December 31, 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):
	Fuel oils	$	33	$	-	$	4	$	37
	Natural gas		4		-		2		6
	Power		-		2		193		195
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		20		-		3		23
	Natural gas		2		-		-		2
	Power		-		1		29		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		77		77
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		10		-		1		11
	Natural gas		2		-		-		2
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	2	$	-	$	-	$	2
	Natural gas		22		-		176		198
	Power		-		2		78		80
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		1		-		-		1
	Natural gas		12		-		14		26
	Power		-		1		8		9
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		162		169
	Power		-		-		217		217
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		1		-		-		1
	Natural gas		2		-		-		2

(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):
	Fuel oils	$	-	$	-	$	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
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		-		-		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
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		-		-		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 as of December 31, 2011:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2011	$	30		$	(a	)	$	17		$	4		$	51
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		12			4			16
Included in regulatory assets/liabilities		19			(a	)		(a	)		(a	)		19
Total realized and unrealized gains (losses)		19			(a	)		12			4			35
Purchases		4			(a	)		1			-			5
Sales		(1	)		(a	)		-			-			(1	)
Settlements		(30	)		(a	)		(20	)		(6	)		(56	)
Transfers into Level 3		-			(a	)		-			-			-
Transfers out of Level 3		(19	)		(a	)		(9	)		(2	)		(30	)
Ending balance at December 31, 2011	$	3		$	(a	)	$	1		$	-		$	4
Change in unrealized gains (losses) related to assets/liabilities held at December 31,2011	$	(11	)	$	(a	)	$	(5	)	$	(2	)	$	(18	)
Natural gas:
Beginning balance at January 1, 2011	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Realized and unrealized gains (losses):													$
Included in regulatory assets/liabilities		(8	)		(107	)		(a	)		(a	)		(115	)
Total realized and unrealized gains (losses)		(8	)		(107	)		(a	)		(a	)	$	(115	)
Purchases		-			1			-			-			1
Sales		-			(1	)		-			-			(1	)
Settlements		8			81			-			-			89
Ending balance at December 31, 2011	$	(14	)	$	(160	)	$	-		$	-		$	(174	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	(6	)	$	(72	)	$	-		$	-		$	(78	)
Power:
Beginning balance at January 1, 2011	$	2		$	(352	)	$	3		$	383		$	36
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			(1	)		(12	)		(13	)
Included in OCI		-			-			-			24			24
Included in regulatory assets/liabilities		17			7			(a	)		51		$	75
Total realized and unrealized gains (losses)		17			7			(1	)		63		$	86
Purchases		30			-			-			35			65
Sales		(1	)		-			-			(21	)	$	(22	)
Settlements		(27	)		205			(2	)		(225	)		(49	)
Transfers into Level 3		(1	)		-			-			1			-
Transfers out of Level 3		1			-			-			(2	)		(1	)
Ending balance at December 31, 2011	$	21		$	(140	)	$	-		$	234		$	115
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	1		$	13		$	(1	)	$	60		$	73
Uranium:
Beginning balance at January 1, 2011	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(a	)		(a	)		(a	)		(3	)
Total realized and unrealized gains (losses)		(3	)		(a	)		(a	)		(a	)		(3	)
Purchases		(1	)		(a	)		(a	)		(a	)		(1	)
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2011	$	(1	)	$	(a	)	$	(a	)	$	(a	)	$	(1	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	-		$	(a	)	$	(a	)	$	(a	)	$	-

(a) Not applicable.

(b) Net gains and losses on fuel oils 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 as of December 31, 2010:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2010	$	32		$	(a	)	$	21		$	7		$	60
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		3			(2	)		1
Included in regulatory assets/liabilities		8			(a	)		(a	)		(a	)		8
Total realized and unrealized gains (losses)		8			(a	)		3			(2	)		9
Purchases		18			(a	)		11			4			33
Settlements		(28	)		(a	)		(18	)		(5	)		(51	)
Ending balance at December 31, 2010	$	30		$	(a	)	$	17		$	4		$	51
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	7		$	(a	)	$	4		$	-		$	11
Natural gas:
Beginning balance at January 1, 2010	$	(6	)	$	(61	)	$	-		$	-		$	(67	)
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(152	)		(a	)		(a	)		(172	)
Total realized and unrealized gains (losses)		(20	)		(152	)		-			-			(172	)
Purchases		-			(5	)		-			-		$	(5	)
Settlements		12			84			-			-			96
Ending balance at December 31, 2010	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	(11	)	$	(82	)	$	-		$	1		$	(92	)
Power:
Beginning balance at January 1, 2010	$	(1	)	$	(422	)	$	1		$	460		$	38
Realized and unrealized gains (losses):
Included in earnings(b)	$	-		$	-		$	2		$	32		$	34
Included in OCI		-			-			-			8			8
Included in regulatory assets/liabilities		27			(107	)		(a	)		95			15
Total realized and unrealized gains (losses)		27			(107	)		2			135			57
Purchases		4			19			(10	)		26			39
Sales		2			-			12			(13	)		1
Settlements		(24	)		158			(2	)		(197	)		(65	)
Transfers into Level 3		-			-			-			(2	)		(2	)
Transfers out of Level 3		(6	)		-			-			(26	)		(32	)
Ending balance at December 31, 2010	$	2		$	(352	)	$	3		$	383		$	36
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(89	)	$	-		$	81		$	(7	)
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(a	)	$	(a	)	$	(a	)	$	(2	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		3			(a	)		(a	)		(a	)		3
Total realized and unrealized gains (losses)		3			(a	)		(a	)		(a	)	$	3
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2010	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(a	)	$	(a	)	$	(a	)	$	1

(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 in or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) 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 between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable on electronic exchanges from the previous reporting period for the years ended December 31, 2011 and 2010. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 2011 and 2010, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2011 and 2010:

	2011			2010
Ameren - derivative commodity contracts:(a)
Transfers into Level 3 / Transfers out of Level 1	$		-	$	(1	)
Transfers out of Level 3 / Transfers into Level 1		(30	)		-
Transfers into Level 3 / Transfers out of Level 2		-			(1	)
Transfers out of Level 3 / Transfers into Level 2		(1	)		(32	)
Net fair value of Level 3 transfers	$	(31	)	$	(34	)
Ameren Missouri – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1		(19	)		-
Transfers into Level 3 / Transfers out of Level 2		(1	)		-
Transfers out of Level 3 / Transfers into Level 2	$	1		$	(6	)
Net fair value of Level 3 transfers	$	(19	)	$	(6	)
Genco – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1	$	(9	)	$	-

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

See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren's pension and postretirement plan assets as of December 31, 2011, as well as a table summarizing the changes in Level 3 plan assets during 2011.

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 issues 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 preferred stock at December 31, 2011 and 2010:

	2011				2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,856	$	7,800	$	7,008	$	7,661
Preferred stock		142		92		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,950	$	4,541	$	3,954	$	4,281
Preferred stock		80		55		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,943	$	1,807	$	2,067
Preferred stock		62		37		62		40
Genco:
Long-term debt (including current portion)	$	824	$	839	$	824	$	826

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

(b) Preferred stock along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.

Ameren Illinois Company [Member]

Fair Value Measurements

NOTE 8 – FAIR VALUE MEASUREMENTS

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:

Level 1: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri's Nuclear Decommissioning Trust Fund.

Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri's Nuclear Decommissioning Trust Fund, including corporate bonds and other fixed-income securities, U.S. treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas swaps and financial power transactions. Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints of the bid/ask spreads. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint.

Level 3: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable, including the financial contracts entered into between Ameren Illinois and Marketing Company. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as well as certain internal assumptions. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a part of our reasonableness review, an evaluation of all sources is performed to identify any anomalies or potential errors.

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.

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 net losses of $2 million, net gains of less than $1 million, and net losses of less than $1 million in 2011, 2010 and 2009, respectively, related to valuation adjustments for counterparty default risk. Genco recorded net losses of less than $1 million, net gains of less than $1 million, and net gains of less than $1 million in 2011, 2010, and 2009, respectively, related to valuation adjustments for counterparty default risk. At December 31, 2011, the counterparty default risk (asset)/liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, $19 million, and less than $(1) million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively. At December 31, 2010, the counterparty default risk liability 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 December 31, 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):
	Fuel oils	$	33	$	-	$	4	$	37
	Natural gas		4		-		2		6
	Power		-		2		193		195
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		20		-		3		23
	Natural gas		2		-		-		2
	Power		-		1		29		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		77		77
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		10		-		1		11
	Natural gas		2		-		-		2
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	2	$	-	$	-	$	2
	Natural gas		22		-		176		198
	Power		-		2		78		80
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		1		-		-		1
	Natural gas		12		-		14		26
	Power		-		1		8		9
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		162		169
	Power		-		-		217		217
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		1		-		-		1
	Natural gas		2		-		-		2

(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):
	Fuel oils	$	-	$	-	$	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
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		-		-		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
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		-		-		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 as of December 31, 2011:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2011	$	30		$	(a	)	$	17		$	4		$	51
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		12			4			16
Included in regulatory assets/liabilities		19			(a	)		(a	)		(a	)		19
Total realized and unrealized gains (losses)		19			(a	)		12			4			35
Purchases		4			(a	)		1			-			5
Sales		(1	)		(a	)		-			-			(1	)
Settlements		(30	)		(a	)		(20	)		(6	)		(56	)
Transfers into Level 3		-			(a	)		-			-			-
Transfers out of Level 3		(19	)		(a	)		(9	)		(2	)		(30	)
Ending balance at December 31, 2011	$	3		$	(a	)	$	1		$	-		$	4
Change in unrealized gains (losses) related to assets/liabilities held at December 31,2011	$	(11	)	$	(a	)	$	(5	)	$	(2	)	$	(18	)
Natural gas:
Beginning balance at January 1, 2011	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Realized and unrealized gains (losses):													$
Included in regulatory assets/liabilities		(8	)		(107	)		(a	)		(a	)		(115	)
Total realized and unrealized gains (losses)		(8	)		(107	)		(a	)		(a	)	$	(115	)
Purchases		-			1			-			-			1
Sales		-			(1	)		-			-			(1	)
Settlements		8			81			-			-			89
Ending balance at December 31, 2011	$	(14	)	$	(160	)	$	-		$	-		$	(174	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	(6	)	$	(72	)	$	-		$	-		$	(78	)
Power:
Beginning balance at January 1, 2011	$	2		$	(352	)	$	3		$	383		$	36
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			(1	)		(12	)		(13	)
Included in OCI		-			-			-			24			24
Included in regulatory assets/liabilities		17			7			(a	)		51		$	75
Total realized and unrealized gains (losses)		17			7			(1	)		63		$	86
Purchases		30			-			-			35			65
Sales		(1	)		-			-			(21	)	$	(22	)
Settlements		(27	)		205			(2	)		(225	)		(49	)
Transfers into Level 3		(1	)		-			-			1			-
Transfers out of Level 3		1			-			-			(2	)		(1	)
Ending balance at December 31, 2011	$	21		$	(140	)	$	-		$	234		$	115
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	1		$	13		$	(1	)	$	60		$	73
Uranium:
Beginning balance at January 1, 2011	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(a	)		(a	)		(a	)		(3	)
Total realized and unrealized gains (losses)		(3	)		(a	)		(a	)		(a	)		(3	)
Purchases		(1	)		(a	)		(a	)		(a	)		(1	)
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2011	$	(1	)	$	(a	)	$	(a	)	$	(a	)	$	(1	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	-		$	(a	)	$	(a	)	$	(a	)	$	-

(a) Not applicable.

(b) Net gains and losses on fuel oils 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 as of December 31, 2010:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2010	$	32		$	(a	)	$	21		$	7		$	60
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		3			(2	)		1
Included in regulatory assets/liabilities		8			(a	)		(a	)		(a	)		8
Total realized and unrealized gains (losses)		8			(a	)		3			(2	)		9
Purchases		18			(a	)		11			4			33
Settlements		(28	)		(a	)		(18	)		(5	)		(51	)
Ending balance at December 31, 2010	$	30		$	(a	)	$	17		$	4		$	51
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	7		$	(a	)	$	4		$	-		$	11
Natural gas:
Beginning balance at January 1, 2010	$	(6	)	$	(61	)	$	-		$	-		$	(67	)
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(152	)		(a	)		(a	)		(172	)
Total realized and unrealized gains (losses)		(20	)		(152	)		-			-			(172	)
Purchases		-			(5	)		-			-		$	(5	)
Settlements		12			84			-			-			96
Ending balance at December 31, 2010	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	(11	)	$	(82	)	$	-		$	1		$	(92	)
Power:
Beginning balance at January 1, 2010	$	(1	)	$	(422	)	$	1		$	460		$	38
Realized and unrealized gains (losses):
Included in earnings(b)	$	-		$	-		$	2		$	32		$	34
Included in OCI		-			-			-			8			8
Included in regulatory assets/liabilities		27			(107	)		(a	)		95			15
Total realized and unrealized gains (losses)		27			(107	)		2			135			57
Purchases		4			19			(10	)		26			39
Sales		2			-			12			(13	)		1
Settlements		(24	)		158			(2	)		(197	)		(65	)
Transfers into Level 3		-			-			-			(2	)		(2	)
Transfers out of Level 3		(6	)		-			-			(26	)		(32	)
Ending balance at December 31, 2010	$	2		$	(352	)	$	3		$	383		$	36
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(89	)	$	-		$	81		$	(7	)
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(a	)	$	(a	)	$	(a	)	$	(2	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		3			(a	)		(a	)		(a	)		3
Total realized and unrealized gains (losses)		3			(a	)		(a	)		(a	)	$	3
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2010	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(a	)	$	(a	)	$	(a	)	$	1

(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 in or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) 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 between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable on electronic exchanges from the previous reporting period for the years ended December 31, 2011 and 2010. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 2011 and 2010, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2011 and 2010:

	2011			2010
Ameren - derivative commodity contracts:(a)
Transfers into Level 3 / Transfers out of Level 1	$		-	$	(1	)
Transfers out of Level 3 / Transfers into Level 1		(30	)		-
Transfers into Level 3 / Transfers out of Level 2		-			(1	)
Transfers out of Level 3 / Transfers into Level 2		(1	)		(32	)
Net fair value of Level 3 transfers	$	(31	)	$	(34	)
Ameren Missouri – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1		(19	)		-
Transfers into Level 3 / Transfers out of Level 2		(1	)		-
Transfers out of Level 3 / Transfers into Level 2	$	1		$	(6	)
Net fair value of Level 3 transfers	$	(19	)	$	(6	)
Genco – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1	$	(9	)	$	-

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

See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren's pension and postretirement plan assets as of December 31, 2011, as well as a table summarizing the changes in Level 3 plan assets during 2011.

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 issues 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 preferred stock at December 31, 2011 and 2010:

	2011				2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,856	$	7,800	$	7,008	$	7,661
Preferred stock		142		92		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,950	$	4,541	$	3,954	$	4,281
Preferred stock		80		55		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,943	$	1,807	$	2,067
Preferred stock		62		37		62		40
Genco:
Long-term debt (including current portion)	$	824	$	839	$	824	$	826

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

(b) Preferred stock 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 8 – FAIR VALUE MEASUREMENTS

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:

Level 1: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri's Nuclear Decommissioning Trust Fund.

Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri's Nuclear Decommissioning Trust Fund, including corporate bonds and other fixed-income securities, U.S. treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas swaps and financial power transactions. Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints of the bid/ask spreads. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint.

Level 3: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable, including the financial contracts entered into between Ameren Illinois and Marketing Company. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as well as certain internal assumptions. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a part of our reasonableness review, an evaluation of all sources is performed to identify any anomalies or potential errors.

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.

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 net losses of $2 million, net gains of less than $1 million, and net losses of less than $1 million in 2011, 2010 and 2009, respectively, related to valuation adjustments for counterparty default risk. Genco recorded net losses of less than $1 million, net gains of less than $1 million, and net gains of less than $1 million in 2011, 2010, and 2009, respectively, related to valuation adjustments for counterparty default risk. At December 31, 2011, the counterparty default risk (asset)/liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, $19 million, and less than $(1) million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively. At December 31, 2010, the counterparty default risk liability 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 December 31, 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):
	Fuel oils	$	33	$	-	$	4	$	37
	Natural gas		4		-		2		6
	Power		-		2		193		195
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		20		-		3		23
	Natural gas		2		-		-		2
	Power		-		1		29		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		77		77
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		10		-		1		11
	Natural gas		2		-		-		2
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	2	$	-	$	-	$	2
	Natural gas		22		-		176		198
	Power		-		2		78		80
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		1		-		-		1
	Natural gas		12		-		14		26
	Power		-		1		8		9
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		162		169
	Power		-		-		217		217
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		1		-		-		1
	Natural gas		2		-		-		2

(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):
	Fuel oils	$	-	$	-	$	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
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		-		-		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
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		-		-		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 as of December 31, 2011:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2011	$	30		$	(a	)	$	17		$	4		$	51
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		12			4			16
Included in regulatory assets/liabilities		19			(a	)		(a	)		(a	)		19
Total realized and unrealized gains (losses)		19			(a	)		12			4			35
Purchases		4			(a	)		1			-			5
Sales		(1	)		(a	)		-			-			(1	)
Settlements		(30	)		(a	)		(20	)		(6	)		(56	)
Transfers into Level 3		-			(a	)		-			-			-
Transfers out of Level 3		(19	)		(a	)		(9	)		(2	)		(30	)
Ending balance at December 31, 2011	$	3		$	(a	)	$	1		$	-		$	4
Change in unrealized gains (losses) related to assets/liabilities held at December 31,2011	$	(11	)	$	(a	)	$	(5	)	$	(2	)	$	(18	)
Natural gas:
Beginning balance at January 1, 2011	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Realized and unrealized gains (losses):													$
Included in regulatory assets/liabilities		(8	)		(107	)		(a	)		(a	)		(115	)
Total realized and unrealized gains (losses)		(8	)		(107	)		(a	)		(a	)	$	(115	)
Purchases		-			1			-			-			1
Sales		-			(1	)		-			-			(1	)
Settlements		8			81			-			-			89
Ending balance at December 31, 2011	$	(14	)	$	(160	)	$	-		$	-		$	(174	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	(6	)	$	(72	)	$	-		$	-		$	(78	)
Power:
Beginning balance at January 1, 2011	$	2		$	(352	)	$	3		$	383		$	36
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			(1	)		(12	)		(13	)
Included in OCI		-			-			-			24			24
Included in regulatory assets/liabilities		17			7			(a	)		51		$	75
Total realized and unrealized gains (losses)		17			7			(1	)		63		$	86
Purchases		30			-			-			35			65
Sales		(1	)		-			-			(21	)	$	(22	)
Settlements		(27	)		205			(2	)		(225	)		(49	)
Transfers into Level 3		(1	)		-			-			1			-
Transfers out of Level 3		1			-			-			(2	)		(1	)
Ending balance at December 31, 2011	$	21		$	(140	)	$	-		$	234		$	115
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	1		$	13		$	(1	)	$	60		$	73
Uranium:
Beginning balance at January 1, 2011	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(a	)		(a	)		(a	)		(3	)
Total realized and unrealized gains (losses)		(3	)		(a	)		(a	)		(a	)		(3	)
Purchases		(1	)		(a	)		(a	)		(a	)		(1	)
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2011	$	(1	)	$	(a	)	$	(a	)	$	(a	)	$	(1	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	-		$	(a	)	$	(a	)	$	(a	)	$	-

(a) Not applicable.

(b) Net gains and losses on fuel oils 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 as of December 31, 2010:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2010	$	32		$	(a	)	$	21		$	7		$	60
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		3			(2	)		1
Included in regulatory assets/liabilities		8			(a	)		(a	)		(a	)		8
Total realized and unrealized gains (losses)		8			(a	)		3			(2	)		9
Purchases		18			(a	)		11			4			33
Settlements		(28	)		(a	)		(18	)		(5	)		(51	)
Ending balance at December 31, 2010	$	30		$	(a	)	$	17		$	4		$	51
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	7		$	(a	)	$	4		$	-		$	11
Natural gas:
Beginning balance at January 1, 2010	$	(6	)	$	(61	)	$	-		$	-		$	(67	)
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(152	)		(a	)		(a	)		(172	)
Total realized and unrealized gains (losses)		(20	)		(152	)		-			-			(172	)
Purchases		-			(5	)		-			-		$	(5	)
Settlements		12			84			-			-			96
Ending balance at December 31, 2010	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	(11	)	$	(82	)	$	-		$	1		$	(92	)
Power:
Beginning balance at January 1, 2010	$	(1	)	$	(422	)	$	1		$	460		$	38
Realized and unrealized gains (losses):
Included in earnings(b)	$	-		$	-		$	2		$	32		$	34
Included in OCI		-			-			-			8			8
Included in regulatory assets/liabilities		27			(107	)		(a	)		95			15
Total realized and unrealized gains (losses)		27			(107	)		2			135			57
Purchases		4			19			(10	)		26			39
Sales		2			-			12			(13	)		1
Settlements		(24	)		158			(2	)		(197	)		(65	)
Transfers into Level 3		-			-			-			(2	)		(2	)
Transfers out of Level 3		(6	)		-			-			(26	)		(32	)
Ending balance at December 31, 2010	$	2		$	(352	)	$	3		$	383		$	36
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(89	)	$	-		$	81		$	(7	)
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(a	)	$	(a	)	$	(a	)	$	(2	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		3			(a	)		(a	)		(a	)		3
Total realized and unrealized gains (losses)		3			(a	)		(a	)		(a	)	$	3
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2010	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(a	)	$	(a	)	$	(a	)	$	1

(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 in or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) 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 between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable on electronic exchanges from the previous reporting period for the years ended December 31, 2011 and 2010. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 2011 and 2010, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2011 and 2010:

	2011			2010
Ameren - derivative commodity contracts:(a)
Transfers into Level 3 / Transfers out of Level 1	$		-	$	(1	)
Transfers out of Level 3 / Transfers into Level 1		(30	)		-
Transfers into Level 3 / Transfers out of Level 2		-			(1	)
Transfers out of Level 3 / Transfers into Level 2		(1	)		(32	)
Net fair value of Level 3 transfers	$	(31	)	$	(34	)
Ameren Missouri – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1		(19	)		-
Transfers into Level 3 / Transfers out of Level 2		(1	)		-
Transfers out of Level 3 / Transfers into Level 2	$	1		$	(6	)
Net fair value of Level 3 transfers	$	(19	)	$	(6	)
Genco – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1	$	(9	)	$	-

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

See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren's pension and postretirement plan assets as of December 31, 2011, as well as a table summarizing the changes in Level 3 plan assets during 2011.

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 issues 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 preferred stock at December 31, 2011 and 2010:

	2011				2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,856	$	7,800	$	7,008	$	7,661
Preferred stock		142		92		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,950	$	4,541	$	3,954	$	4,281
Preferred stock		80		55		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,943	$	1,807	$	2,067
Preferred stock		62		37		62		40
Genco:
Long-term debt (including current portion)	$	824	$	839	$	824	$	826

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

(b) Preferred stock 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 8 – FAIR VALUE MEASUREMENTS

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:

Level 1: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri's Nuclear Decommissioning Trust Fund.

Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri's Nuclear Decommissioning Trust Fund, including corporate bonds and other fixed-income securities, U.S. treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas swaps and financial power transactions. Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints of the bid/ask spreads. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint.

Level 3: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable, including the financial contracts entered into between Ameren Illinois and Marketing Company. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as well as certain internal assumptions. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a part of our reasonableness review, an evaluation of all sources is performed to identify any anomalies or potential errors.

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.

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 net losses of $2 million, net gains of less than $1 million, and net losses of less than $1 million in 2011, 2010 and 2009, respectively, related to valuation adjustments for counterparty default risk. Genco recorded net losses of less than $1 million, net gains of less than $1 million, and net gains of less than $1 million in 2011, 2010, and 2009, respectively, related to valuation adjustments for counterparty default risk. At December 31, 2011, the counterparty default risk (asset)/liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, $19 million, and less than $(1) million for Ameren, Ameren Missouri, Ameren Illinois and Genco, respectively. At December 31, 2010, the counterparty default risk liability 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 December 31, 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):
	Fuel oils	$	33	$	-	$	4	$	37
	Natural gas		4		-		2		6
	Power		-		2		193		195
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		20		-		3		23
	Natural gas		2		-		-		2
	Power		-		1		29		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		3		-		-		3
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		44		-		44
	Municipal bonds		-		1		-		1
	U.S. treasury and agency securities		-		65		-		65
	Asset-backed securities		-		10		-		10
	Other		-		1		-		1
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		77		77
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		10		-		1		11
	Natural gas		2		-		-		2
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	2	$	-	$	-	$	2
	Natural gas		22		-		176		198
	Power		-		2		78		80
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		1		-		-		1
	Natural gas		12		-		14		26
	Power		-		1		8		9
	Uranium		-		-		1		1
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		162		169
	Power		-		-		217		217
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		1		-		-		1
	Natural gas		2		-		-		2

(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):
	Fuel oils	$	-	$	-	$	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
Ameren	Derivative assets - commodity contracts(b):
Missouri	Fuel oils		-		-		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
Ameren	Derivative assets - commodity contracts(b):
Illinois	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts(b):
	Fuel oils		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Fuel oils	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
Ameren	Derivative liabilities - commodity contracts(b):
Missouri	Fuel oils		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
Ameren	Derivative liabilities - commodity contracts(b):
Illinois	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts(b):
	Fuel oils		-		-		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 as of December 31, 2011:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2011	$	30		$	(a	)	$	17		$	4		$	51
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		12			4			16
Included in regulatory assets/liabilities		19			(a	)		(a	)		(a	)		19
Total realized and unrealized gains (losses)		19			(a	)		12			4			35
Purchases		4			(a	)		1			-			5
Sales		(1	)		(a	)		-			-			(1	)
Settlements		(30	)		(a	)		(20	)		(6	)		(56	)
Transfers into Level 3		-			(a	)		-			-			-
Transfers out of Level 3		(19	)		(a	)		(9	)		(2	)		(30	)
Ending balance at December 31, 2011	$	3		$	(a	)	$	1		$	-		$	4
Change in unrealized gains (losses) related to assets/liabilities held at December 31,2011	$	(11	)	$	(a	)	$	(5	)	$	(2	)	$	(18	)
Natural gas:
Beginning balance at January 1, 2011	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Realized and unrealized gains (losses):													$
Included in regulatory assets/liabilities		(8	)		(107	)		(a	)		(a	)		(115	)
Total realized and unrealized gains (losses)		(8	)		(107	)		(a	)		(a	)	$	(115	)
Purchases		-			1			-			-			1
Sales		-			(1	)		-			-			(1	)
Settlements		8			81			-			-			89
Ending balance at December 31, 2011	$	(14	)	$	(160	)	$	-		$	-		$	(174	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	(6	)	$	(72	)	$	-		$	-		$	(78	)
Power:
Beginning balance at January 1, 2011	$	2		$	(352	)	$	3		$	383		$	36
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			(1	)		(12	)		(13	)
Included in OCI		-			-			-			24			24
Included in regulatory assets/liabilities		17			7			(a	)		51		$	75
Total realized and unrealized gains (losses)		17			7			(1	)		63		$	86
Purchases		30			-			-			35			65
Sales		(1	)		-			-			(21	)	$	(22	)
Settlements		(27	)		205			(2	)		(225	)		(49	)
Transfers into Level 3		(1	)		-			-			1			-
Transfers out of Level 3		1			-			-			(2	)		(1	)
Ending balance at December 31, 2011	$	21		$	(140	)	$	-		$	234		$	115
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	1		$	13		$	(1	)	$	60		$	73
Uranium:
Beginning balance at January 1, 2011	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(a	)		(a	)		(a	)		(3	)
Total realized and unrealized gains (losses)		(3	)		(a	)		(a	)		(a	)		(3	)
Purchases		(1	)		(a	)		(a	)		(a	)		(1	)
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2011	$	(1	)	$	(a	)	$	(a	)	$	(a	)	$	(1	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2011	$	-		$	(a	)	$	(a	)	$	(a	)	$	-

(a) Not applicable.

(b) Net gains and losses on fuel oils 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 as of December 31, 2010:

	Net derivative commodity contracts
	Ameren Missouri			Ameren Illinois			Genco			Other(c)			Ameren
Fuel oils:
Beginning balance at January 1, 2010	$	32		$	(a	)	$	21		$	7		$	60
Realized and unrealized gains (losses):
Included in earnings(b)		-			(a	)		3			(2	)		1
Included in regulatory assets/liabilities		8			(a	)		(a	)		(a	)		8
Total realized and unrealized gains (losses)		8			(a	)		3			(2	)		9
Purchases		18			(a	)		11			4			33
Settlements		(28	)		(a	)		(18	)		(5	)		(51	)
Ending balance at December 31, 2010	$	30		$	(a	)	$	17		$	4		$	51
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	7		$	(a	)	$	4		$	-		$	11
Natural gas:
Beginning balance at January 1, 2010	$	(6	)	$	(61	)	$	-		$	-		$	(67	)
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(152	)		(a	)		(a	)		(172	)
Total realized and unrealized gains (losses)		(20	)		(152	)		-			-			(172	)
Purchases		-			(5	)		-			-		$	(5	)
Settlements		12			84			-			-			96
Ending balance at December 31, 2010	$	(14	)	$	(134	)	$	-		$	-		$	(148	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	(11	)	$	(82	)	$	-		$	1		$	(92	)
Power:
Beginning balance at January 1, 2010	$	(1	)	$	(422	)	$	1		$	460		$	38
Realized and unrealized gains (losses):
Included in earnings(b)	$	-		$	-		$	2		$	32		$	34
Included in OCI		-			-			-			8			8
Included in regulatory assets/liabilities		27			(107	)		(a	)		95			15
Total realized and unrealized gains (losses)		27			(107	)		2			135			57
Purchases		4			19			(10	)		26			39
Sales		2			-			12			(13	)		1
Settlements		(24	)		158			(2	)		(197	)		(65	)
Transfers into Level 3		-			-			-			(2	)		(2	)
Transfers out of Level 3		(6	)		-			-			(26	)		(32	)
Ending balance at December 31, 2010	$	2		$	(352	)	$	3		$	383		$	36
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(89	)	$	-		$	81		$	(7	)
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(a	)	$	(a	)	$	(a	)	$	(2	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		3			(a	)		(a	)		(a	)		3
Total realized and unrealized gains (losses)		3			(a	)		(a	)		(a	)	$	3
Settlements		1			(a	)		(a	)		(a	)		1
Ending balance at December 31, 2010	$	2		$	(a	)	$	(a	)	$	(a	)	$	2
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2010	$	1		$	(a	)	$	(a	)	$	(a	)	$	1

(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 in or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) 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 between Level 2 and Level 3 were primarily caused by changes in availability of financial power trades observable on electronic exchanges from the previous reporting period for the years ended December 31, 2011 and 2010. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 2011 and 2010, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2011 and 2010:

	2011			2010
Ameren - derivative commodity contracts:(a)
Transfers into Level 3 / Transfers out of Level 1	$		-	$	(1	)
Transfers out of Level 3 / Transfers into Level 1		(30	)		-
Transfers into Level 3 / Transfers out of Level 2		-			(1	)
Transfers out of Level 3 / Transfers into Level 2		(1	)		(32	)
Net fair value of Level 3 transfers	$	(31	)	$	(34	)
Ameren Missouri – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1		(19	)		-
Transfers into Level 3 / Transfers out of Level 2		(1	)		-
Transfers out of Level 3 / Transfers into Level 2	$	1		$	(6	)
Net fair value of Level 3 transfers	$	(19	)	$	(6	)
Genco – derivative commodity contracts:
Transfers out of Level 3 / Transfers into Level 1	$	(9	)	$	-

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

See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren's pension and postretirement plan assets as of December 31, 2011, as well as a table summarizing the changes in Level 3 plan assets during 2011.

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 issues 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 preferred stock at December 31, 2011 and 2010:

	2011				2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)(b)
Long-term debt and capital lease obligations (including current portion)	$	6,856	$	7,800	$	7,008	$	7,661
Preferred stock		142		92		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,950	$	4,541	$	3,954	$	4,281
Preferred stock		80		55		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,943	$	1,807	$	2,067
Preferred stock		62		37		62		40
Genco:
Long-term debt (including current portion)	$	824	$	839	$	824	$	826

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

(b) Preferred stock along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.