Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

Open Gross Derivative Volumes By Commodity Type

	Quantity (in millions, except as indicated)
Commodity	NPNS Contracts(a)						Cash Flow Hedges(b)						Other Derivatives(c)						Derivatives That Qualify for Regulatory Deferral(d)
	2012			2011			2012			2011			2012			2011			2012			2011
Coal (in tons)
Ameren Missouri		106			116			(e	)		(e	)		-			(e	)		(e	)		(e	)
Genco		31			24			(e	)		(e	)		5			(e	)		(e	)		(e	)
Other(f)		9			7			(e	)		(e	)		1			(e	)		(e	)		(e	)
Ameren		146			147			(e	)		(e	)		6			(e	)		(e	)		(e	)
Fuel oils (in gallons)(g)
Ameren Missouri		(e	)		(e	)		(e	)		(e	)		(e	)		(e	)		59			53
Genco		(e	)		(e	)		(e	)		(e	)		43			27			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		12			9			(e	)		(e	)
Ameren		(e	)		(e	)		(e	)		(e	)		55			36			59			53
Natural gas (in mmbtu)
Ameren Missouri		6			8			(e	)		(e	)		16			9			22			19
Ameren Illinois		27			42			(e	)		(e	)		(e	)		(e	)		153			174
Genco		(e	)		(e	)		(e	)		(e	)		26			7			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		1			1			(e	)		(e	)
Ameren		33			50			(e	)		(e	)		43			17			175			193
Power (in megawatthours)
Ameren Missouri		4			1			(e	)		(e	)		1			1			13			6
Ameren Illinois		22			11			(e	)		(e	)		(e	)		(e	)		19			24
Genco		(e	)		(e	)		(e	)		(e	)		-			-			(e	)		(e	)
Other(f)		69			61			17			17			56			30			(4	)		(9	)
Ameren		95			73			17			17			57			31			28			21
Uranium (pounds in thousands)
Ameren Missouri & Ameren		5,361			5,553			(e	)		(e	)		(e	)		(e	)		131			148

(a) Contracts through December 2017, March 2015, September 2035, and October 2024 for coal, natural gas, power, and uranium, respectively, as of June 30, 2012.

(b) Contracts through December 2016 for power as of June 30, 2012.

(c) Contracts through December 2014, October 2016, April 2015, and December 2016 for coal, fuel oils, natural gas, and power, respectively, as of June 30, 2012.

(d) Contracts through October 2014, October 2016, May 2032, and December 2013 for fuel oils, natural gas, power, and uranium, respectively, as of June 30, 2012.

(e) Not applicable.

(f) Includes AERG contracts for coal and fuel oils, Marketing Company contracts for natural gas and power, and intercompany eliminations for power.

(g) Fuel oils consist of heating and crude oil.

Derivative Instruments Carrying Value

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
2012:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	23		$	(b	)	$	(b	)	$	(b	)
	Other assets		31			-			-			-
	Total assets	$	54		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	MTM derivative liabilities	$	1		$	(b	)	$	-		$	(b	)
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	13		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			8			-			4
	Other assets		5			4			-			1
Natural gas	MTM derivative assets		10			(b	)		(b	)		(b	)
	Other current assets		-			2			2			5
	Other assets		-			-			-			-
Power	MTM derivative assets		110			(b	)		(b	)		(b	)
	Other current assets		-			39			-			-
	Other assets		35			2			-			-
	Total assets	$	173		$	55		$	2		$	10
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Coal	MTM derivative liabilities	$	4		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			-			-			4
	Other deferred credits and liabilities		6			-			-			4
Fuel oils	MTM derivative liabilities		5			(b	)		-			(b	)
	Other current liabilities		-			2			-			2
	Other deferred credits and liabilities		6			2			-			3
Natural gas	MTM derivative liabilities		91			(b	)		78			(b	)
	Other current liabilities		-			12			-			1
	Other deferred credits and liabilities		77			11			66			-
Power	MTM derivative liabilities		96			(b	)		19			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		114			(b	)

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
	Other current liabilities	$	-		$	15		$	-		$	-
	Other deferred credits and liabilities		117			2			88			-
Uranium	MTM derivative liabilities		1			(b	)		-			(b	)
	Other current liabilities		-			1			-			-
	Total liabilities	$	403		$	45		$	365		$	14
2011:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	8		$	(b	)	$	(b	)	$	(b	)
	Other assets		16			-			-			-
	Total assets	$	24		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	Other deferred credits and liabilities	$	1		$	-		$	-		$	-
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	29		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			17			-			10
	Other assets		8			6			-			1
Natural gas	MTM derivative assets		6			(b	)		(b	)		(b	)
	Other current assets		-			2			1			2
	Other assets		-			-			1			-
Power	MTM derivative assets		72			(b	)		(b	)		(b	)
	Other current assets		-			30			-			-
	Other assets		99			-			77			-
	Total assets	$	214		$	55		$	79		$	13
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	2		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			1			-			1
Natural gas	MTM derivative liabilities		106			(b	)		90			(b	)
	Other current liabilities		-			13			-			2
	Other deferred credits and liabilities		92			13			79			-
Power	MTM derivative liabilities		53			(b	)		9			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		200			(b	)
	Other current liabilities		-			9			-			-
	Other deferred credits and liabilities		26			-			8			-
Uranium	Other deferred credits and liabilities		1			1			-			-
	Total liabilities	$	280		$	37		$	386		$	3

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

(b) Balance sheet line item not applicable to registrant.

(c) Includes derivatives subject to regulatory deferral.

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI

	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other (a)
2012:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	45		$	-		$	-		$	-		$	45
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		5			5			-			-			-
Natural gas derivative contracts(f)		(163	)		(21	)		(142	)		-			-
Power derivative contracts(g)		(82	)		24			(221	)		-			115
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-
2011:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	19		$	-		$	-		$	-		$	19
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		19			19			-			-			-
Natural gas derivative contracts(f)		(191	)		(24	)		(167	)		-			-
Power derivative contracts(g)		81			21			(140	)		-			200
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-

(a) Includes amounts for Marketing Company and intercompany eliminations.

(b) Represents net gains associated with power derivative contracts at Ameren. These contracts are a partial hedge of electricity price exposure through December 2016 as of June 30, 2012. Current gains of $17 million and $5 million were recorded at Ameren as of June 30, 2012, and December 31, 2011, respectively.

(c) Includes net gains associated with interest rate swaps at Genco that were a partial hedge of the interest rate on debt issued in June 2002. The swaps covered the first 10 years of debt that has a 30-year maturity, and the gain in OCI was amortized over a 10-year period that began in June 2002. The balance of the gain was fully amortized as of June 30, 2012. The carrying value at December 31, 2011, was less than $1 million.

(d) Includes net losses associated with interest rate swaps at Genco. The swaps were executed during the fourth quarter of 2007 as a partial hedge of interest rate risks associated with Genco’s April 2008 debt issuance. The loss on the interest rate swaps is being amortized over a 10-year period that began in April 2008. The carrying value at June 30, 2012, and December 31, 2011, was a loss of $8 million and $9 million, respectively. Over the next twelve months, $1.4 million of the loss will be amortized.

(e) Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2014 as of June 30, 2012. Current gains deferred as regulatory liabilities include $7 million and $7 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current gains deferred as regulatory liabilities include $16 million and $16 million at Ameren and Ameren Missouri as of December 31, 2011, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

(f) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2016 at Ameren, Ameren Missouri, and Ameren Illinois, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Illinois, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $88 million, $10 million, and $78 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $1 million and $1 million at Ameren and Ameren Illinois, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $101 million, $11 million, and $90 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(g) Represents net losses associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $37 million and $37 million at Ameren and Ameren Missouri, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $33 million, $14 million, and $133 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $29 million and $29 million at Ameren and Ameren Missouri, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $17 million, $8 million, and $209 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(h) Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of our uranium requirements through December 2013 as of June 30, 2012. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include less than $1 million and less than $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

Maximum Exposure If Counterparties Fail To Perform On Contracts

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	1	$	1	$	2	$	6	$	15	$	4		$	-	$	-	$	29
AIC		-		-		1		-		1		-			-		-		2
	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
Genco	$	-	$	-	$	2	$	-	$	1	$	-		$	3	$	-	$	6
Other(b)		187		10		46		14		18		465	(c)		1		103		844
Ameren	$	188	$	11	$	51	$	20	$	35	$	469		$	4	$	103	$	881
2011:
AMO	$	1	$	35	$	1	$	4	$	26	$	4		$	-	$	-	$	71
AIC		-		-		84		-		1		-			-		-		85
Genco		-		1		1		2		6		-			3		-		13
Other(b)		275		1		3		10		51		194	(c)		-		87		621
Ameren	$	276	$	37	$	89	$	16	$	84	$	198		$	3	$	87	$	790

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Potential Loss On Counterparty Exposures

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	-	$	-	$	2	$	2	$	8	$	4		$	-	$	-	$	16
AIC		-		-		1		-		-		-			-		-		1
Genco		-		-		1		-		-		-			1		-		2
Other(b)		186		5		38		3		13		459	(c)		-		102		806
Ameren	$	186	$	5	$	42	$	5	$	21	$	463		$	1	$	102	$	825
2011:
AMO	$	1	$	35	$	1	$	3	$	22	$	4		$	-	$	-	$	66
AIC		-		-		84		-		-		-			-		-		84
Genco		-		-		-		1		1		-			2		-		4
Other(b)		273		-		3		5		42		187	(c)		-		86		596
Ameren	$	274	$	35	$	88	$	9	$	65	$	191		$	2	$	86	$	750

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Derivative Instruments With Credit Risk-Related Contingent Features

	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional  Collateral Required(b)
2012:
Ameren Missouri	$	146	$	7	$	125
Ameren Illinois		174		91		106
Genco		48		1		41
Other(c)		86		12		63
Ameren	$	454	$	111	$	335
2011:
Ameren Missouri	$	102	$	8	$	86
Ameren Illinois		220		96		125
Genco		55		1		58
Other(c)		79		11		63
Ameren	$	456	$	116	$	332

(a) Prior to consideration of master trading and netting agreements and including NPNS contract exposures.

(b) As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is after consideration of the effects of such agreements.

(c) Includes amounts for Marketing Company and Ameren (parent).

Cash Flow Hedges

	Gain (Loss) Recognized in OCI(a)			Location of (Gain) Loss Reclassified from OCI into Income(b)	(Gain) Loss Reclassified from OCI into Income(b)			Location of Gain (Loss) Recognized in Income(c)	Gain (Loss) Recognized in Income(c)
Three Months
2012:
Ameren:(d)
Power	$	5		Operating Revenues - Electric	$	2		Operating Revenues - Electric	$	(1	)
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
2011:
Ameren:(d)
Power	$	(3	)	Operating Revenues - Electric	$	1		Operating Revenues - Electric	$	3
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Six Months
2012:
Ameren:(d)
Power	$	23		Operating Revenues - Electric	$	6		Operating Revenues - Electric	$	1
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
2011:
Ameren:(d)
Power	$	(7	)	Operating Revenues - Electric	$	2		Operating Revenues - Electric	$	2
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-

(a) Effective portion of gain (loss).

(b) Effective portion of (gain) loss on settlements.

(c) Ineffective portion of gain (loss) and amount excluded from effectiveness testing.

(d) Includes amounts from Ameren registrant and nonregistrant subsidiaries.

(e) Represents interest rate swaps settled in prior periods. The cumulative gain and loss on the interest rate swaps is being amortized into income over a 10-year period.

(f) Less than $1 million.

Other Derivatives

		Location of Gain (Loss) Recognized in Income	Gain (Loss) Recognized in Income
			Three Months						Six Months
			2012			2011			2012			2011
Ameren(a)	Coal	Operating Expenses - Fuel	$	(6	)	$	-		$	(10	)	$	-
	Fuel oils	Operating Expenses - Fuel		(18	)		(9	)		(13	)		10
	Natural gas (generation)	Operating Expenses - Fuel		4			-			5			-
	Power	Operating Revenues - Electric		7			(5	)		6			(7	)
		Total	$	(13	)	$	(14	)	$	(12	)	$	3
Ameren Missouri	Natural gas (generation)	Operating Expenses - Fuel	$	-		$	-		$	-		$	(1	)
Genco	Coal	Operating Expenses - Fuel	$	(5	)	$	-		$	(8	)	$	-
	Fuel oils	Operating Expenses - Fuel		(14	)		(8	)		(10	)		7
	Natural gas (generation)	Operating Expenses - Fuel		4			-			4			-
	Power	Operating Revenues		-			(1	)		-			(1	)
		Total	$	(15	)	$	(9	)	$	(14	)	$	6

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

Derivatives That Qualify For Regulatory Deferral

		Gain (Loss) Recognized in Regulatory  Liabilities or Regulatory Assets
		Three Months						Six Months
		2012			2011			2012			2011
Ameren(a)	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		46			3			28			34
	Power		(1	)		88			(163	)		90
	Uranium		-			(3	)		-			(4	)
	Total	$	26		$	75		$	(149	)	$	136
Ameren Missouri	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		5			1			3			4
	Power		4			23			3			23
	Uranium		-			(3	)		-			(4	)
	Total	$	(10	)	$	8		$	(8	)	$	39
Ameren Illinois	Natural gas	$	41		$	2		$	25		$	30
	Power		63			121			(81	)		148
	Total	$	104		$	123		$	(56	)	$	178

(a) Includes amounts for intercompany eliminations.

Ameren Missouri [Member]

Open Gross Derivative Volumes By Commodity Type

	Quantity (in millions, except as indicated)
Commodity	NPNS Contracts(a)						Cash Flow Hedges(b)						Other Derivatives(c)						Derivatives That Qualify for Regulatory Deferral(d)
	2012			2011			2012			2011			2012			2011			2012			2011
Coal (in tons)
Ameren Missouri		106			116			(e	)		(e	)		-			(e	)		(e	)		(e	)
Genco		31			24			(e	)		(e	)		5			(e	)		(e	)		(e	)
Other(f)		9			7			(e	)		(e	)		1			(e	)		(e	)		(e	)
Ameren		146			147			(e	)		(e	)		6			(e	)		(e	)		(e	)
Fuel oils (in gallons)(g)
Ameren Missouri		(e	)		(e	)		(e	)		(e	)		(e	)		(e	)		59			53
Genco		(e	)		(e	)		(e	)		(e	)		43			27			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		12			9			(e	)		(e	)
Ameren		(e	)		(e	)		(e	)		(e	)		55			36			59			53
Natural gas (in mmbtu)
Ameren Missouri		6			8			(e	)		(e	)		16			9			22			19
Ameren Illinois		27			42			(e	)		(e	)		(e	)		(e	)		153			174
Genco		(e	)		(e	)		(e	)		(e	)		26			7			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		1			1			(e	)		(e	)
Ameren		33			50			(e	)		(e	)		43			17			175			193
Power (in megawatthours)
Ameren Missouri		4			1			(e	)		(e	)		1			1			13			6
Ameren Illinois		22			11			(e	)		(e	)		(e	)		(e	)		19			24
Genco		(e	)		(e	)		(e	)		(e	)		-			-			(e	)		(e	)
Other(f)		69			61			17			17			56			30			(4	)		(9	)
Ameren		95			73			17			17			57			31			28			21
Uranium (pounds in thousands)
Ameren Missouri & Ameren		5,361			5,553			(e	)		(e	)		(e	)		(e	)		131			148

(a) Contracts through December 2017, March 2015, September 2035, and October 2024 for coal, natural gas, power, and uranium, respectively, as of June 30, 2012.

(b) Contracts through December 2016 for power as of June 30, 2012.

(c) Contracts through December 2014, October 2016, April 2015, and December 2016 for coal, fuel oils, natural gas, and power, respectively, as of June 30, 2012.

(d) Contracts through October 2014, October 2016, May 2032, and December 2013 for fuel oils, natural gas, power, and uranium, respectively, as of June 30, 2012.

(e) Not applicable.

(f) Includes AERG contracts for coal and fuel oils, Marketing Company contracts for natural gas and power, and intercompany eliminations for power.

(g) Fuel oils consist of heating and crude oil.

Derivative Instruments Carrying Value

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
2012:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	23		$	(b	)	$	(b	)	$	(b	)
	Other assets		31			-			-			-
	Total assets	$	54		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	MTM derivative liabilities	$	1		$	(b	)	$	-		$	(b	)
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	13		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			8			-			4
	Other assets		5			4			-			1
Natural gas	MTM derivative assets		10			(b	)		(b	)		(b	)
	Other current assets		-			2			2			5
	Other assets		-			-			-			-
Power	MTM derivative assets		110			(b	)		(b	)		(b	)
	Other current assets		-			39			-			-
	Other assets		35			2			-			-
	Total assets	$	173		$	55		$	2		$	10
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Coal	MTM derivative liabilities	$	4		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			-			-			4
	Other deferred credits and liabilities		6			-			-			4
Fuel oils	MTM derivative liabilities		5			(b	)		-			(b	)
	Other current liabilities		-			2			-			2
	Other deferred credits and liabilities		6			2			-			3
Natural gas	MTM derivative liabilities		91			(b	)		78			(b	)
	Other current liabilities		-			12			-			1
	Other deferred credits and liabilities		77			11			66			-
Power	MTM derivative liabilities		96			(b	)		19			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		114			(b	)

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
	Other current liabilities	$	-		$	15		$	-		$	-
	Other deferred credits and liabilities		117			2			88			-
Uranium	MTM derivative liabilities		1			(b	)		-			(b	)
	Other current liabilities		-			1			-			-
	Total liabilities	$	403		$	45		$	365		$	14
2011:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	8		$	(b	)	$	(b	)	$	(b	)
	Other assets		16			-			-			-
	Total assets	$	24		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	Other deferred credits and liabilities	$	1		$	-		$	-		$	-
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	29		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			17			-			10
	Other assets		8			6			-			1
Natural gas	MTM derivative assets		6			(b	)		(b	)		(b	)
	Other current assets		-			2			1			2
	Other assets		-			-			1			-
Power	MTM derivative assets		72			(b	)		(b	)		(b	)
	Other current assets		-			30			-			-
	Other assets		99			-			77			-
	Total assets	$	214		$	55		$	79		$	13
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	2		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			1			-			1
Natural gas	MTM derivative liabilities		106			(b	)		90			(b	)
	Other current liabilities		-			13			-			2
	Other deferred credits and liabilities		92			13			79			-
Power	MTM derivative liabilities		53			(b	)		9			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		200			(b	)
	Other current liabilities		-			9			-			-
	Other deferred credits and liabilities		26			-			8			-
Uranium	Other deferred credits and liabilities		1			1			-			-
	Total liabilities	$	280		$	37		$	386		$	3

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

(b) Balance sheet line item not applicable to registrant.

(c) Includes derivatives subject to regulatory deferral.

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI

	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other (a)
2012:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	45		$	-		$	-		$	-		$	45
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		5			5			-			-			-
Natural gas derivative contracts(f)		(163	)		(21	)		(142	)		-			-
Power derivative contracts(g)		(82	)		24			(221	)		-			115
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-
2011:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	19		$	-		$	-		$	-		$	19
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		19			19			-			-			-
Natural gas derivative contracts(f)		(191	)		(24	)		(167	)		-			-
Power derivative contracts(g)		81			21			(140	)		-			200
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-

(a) Includes amounts for Marketing Company and intercompany eliminations.

(b) Represents net gains associated with power derivative contracts at Ameren. These contracts are a partial hedge of electricity price exposure through December 2016 as of June 30, 2012. Current gains of $17 million and $5 million were recorded at Ameren as of June 30, 2012, and December 31, 2011, respectively.

(c) Includes net gains associated with interest rate swaps at Genco that were a partial hedge of the interest rate on debt issued in June 2002. The swaps covered the first 10 years of debt that has a 30-year maturity, and the gain in OCI was amortized over a 10-year period that began in June 2002. The balance of the gain was fully amortized as of June 30, 2012. The carrying value at December 31, 2011, was less than $1 million.

(d) Includes net losses associated with interest rate swaps at Genco. The swaps were executed during the fourth quarter of 2007 as a partial hedge of interest rate risks associated with Genco’s April 2008 debt issuance. The loss on the interest rate swaps is being amortized over a 10-year period that began in April 2008. The carrying value at June 30, 2012, and December 31, 2011, was a loss of $8 million and $9 million, respectively. Over the next twelve months, $1.4 million of the loss will be amortized.

(e) Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2014 as of June 30, 2012. Current gains deferred as regulatory liabilities include $7 million and $7 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current gains deferred as regulatory liabilities include $16 million and $16 million at Ameren and Ameren Missouri as of December 31, 2011, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

(f) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2016 at Ameren, Ameren Missouri, and Ameren Illinois, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Illinois, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $88 million, $10 million, and $78 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $1 million and $1 million at Ameren and Ameren Illinois, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $101 million, $11 million, and $90 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(g) Represents net losses associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $37 million and $37 million at Ameren and Ameren Missouri, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $33 million, $14 million, and $133 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $29 million and $29 million at Ameren and Ameren Missouri, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $17 million, $8 million, and $209 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(h) Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of our uranium requirements through December 2013 as of June 30, 2012. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include less than $1 million and less than $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

Maximum Exposure If Counterparties Fail To Perform On Contracts

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	1	$	1	$	2	$	6	$	15	$	4		$	-	$	-	$	29
AIC		-		-		1		-		1		-			-		-		2
	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
Genco	$	-	$	-	$	2	$	-	$	1	$	-		$	3	$	-	$	6
Other(b)		187		10		46		14		18		465	(c)		1		103		844
Ameren	$	188	$	11	$	51	$	20	$	35	$	469		$	4	$	103	$	881
2011:
AMO	$	1	$	35	$	1	$	4	$	26	$	4		$	-	$	-	$	71
AIC		-		-		84		-		1		-			-		-		85
Genco		-		1		1		2		6		-			3		-		13
Other(b)		275		1		3		10		51		194	(c)		-		87		621
Ameren	$	276	$	37	$	89	$	16	$	84	$	198		$	3	$	87	$	790

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Potential Loss On Counterparty Exposures

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	-	$	-	$	2	$	2	$	8	$	4		$	-	$	-	$	16
AIC		-		-		1		-		-		-			-		-		1
Genco		-		-		1		-		-		-			1		-		2
Other(b)		186		5		38		3		13		459	(c)		-		102		806
Ameren	$	186	$	5	$	42	$	5	$	21	$	463		$	1	$	102	$	825
2011:
AMO	$	1	$	35	$	1	$	3	$	22	$	4		$	-	$	-	$	66
AIC		-		-		84		-		-		-			-		-		84
Genco		-		-		-		1		1		-			2		-		4
Other(b)		273		-		3		5		42		187	(c)		-		86		596
Ameren	$	274	$	35	$	88	$	9	$	65	$	191		$	2	$	86	$	750

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Derivative Instruments With Credit Risk-Related Contingent Features

	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional  Collateral Required(b)
2012:
Ameren Missouri	$	146	$	7	$	125
Ameren Illinois		174		91		106
Genco		48		1		41
Other(c)		86		12		63
Ameren	$	454	$	111	$	335
2011:
Ameren Missouri	$	102	$	8	$	86
Ameren Illinois		220		96		125
Genco		55		1		58
Other(c)		79		11		63
Ameren	$	456	$	116	$	332

(a) Prior to consideration of master trading and netting agreements and including NPNS contract exposures.

(b) As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is after consideration of the effects of such agreements.

(c) Includes amounts for Marketing Company and Ameren (parent).

Other Derivatives

		Location of Gain (Loss) Recognized in Income	Gain (Loss) Recognized in Income
			Three Months						Six Months
			2012			2011			2012			2011
Ameren(a)	Coal	Operating Expenses - Fuel	$	(6	)	$	-		$	(10	)	$	-
	Fuel oils	Operating Expenses - Fuel		(18	)		(9	)		(13	)		10
	Natural gas (generation)	Operating Expenses - Fuel		4			-			5			-
	Power	Operating Revenues - Electric		7			(5	)		6			(7	)
		Total	$	(13	)	$	(14	)	$	(12	)	$	3
Ameren Missouri	Natural gas (generation)	Operating Expenses - Fuel	$	-		$	-		$	-		$	(1	)
Genco	Coal	Operating Expenses - Fuel	$	(5	)	$	-		$	(8	)	$	-
	Fuel oils	Operating Expenses - Fuel		(14	)		(8	)		(10	)		7
	Natural gas (generation)	Operating Expenses - Fuel		4			-			4			-
	Power	Operating Revenues		-			(1	)		-			(1	)
		Total	$	(15	)	$	(9	)	$	(14	)	$	6

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

Derivatives That Qualify For Regulatory Deferral

		Gain (Loss) Recognized in Regulatory  Liabilities or Regulatory Assets
		Three Months						Six Months
		2012			2011			2012			2011
Ameren(a)	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		46			3			28			34
	Power		(1	)		88			(163	)		90
	Uranium		-			(3	)		-			(4	)
	Total	$	26		$	75		$	(149	)	$	136
Ameren Missouri	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		5			1			3			4
	Power		4			23			3			23
	Uranium		-			(3	)		-			(4	)
	Total	$	(10	)	$	8		$	(8	)	$	39
Ameren Illinois	Natural gas	$	41		$	2		$	25		$	30
	Power		63			121			(81	)		148
	Total	$	104		$	123		$	(56	)	$	178

(a) Includes amounts for intercompany eliminations.

Ameren Illinois Company [Member]

Open Gross Derivative Volumes By Commodity Type

	Quantity (in millions, except as indicated)
Commodity	NPNS Contracts(a)						Cash Flow Hedges(b)						Other Derivatives(c)						Derivatives That Qualify for Regulatory Deferral(d)
	2012			2011			2012			2011			2012			2011			2012			2011
Coal (in tons)
Ameren Missouri		106			116			(e	)		(e	)		-			(e	)		(e	)		(e	)
Genco		31			24			(e	)		(e	)		5			(e	)		(e	)		(e	)
Other(f)		9			7			(e	)		(e	)		1			(e	)		(e	)		(e	)
Ameren		146			147			(e	)		(e	)		6			(e	)		(e	)		(e	)
Fuel oils (in gallons)(g)
Ameren Missouri		(e	)		(e	)		(e	)		(e	)		(e	)		(e	)		59			53
Genco		(e	)		(e	)		(e	)		(e	)		43			27			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		12			9			(e	)		(e	)
Ameren		(e	)		(e	)		(e	)		(e	)		55			36			59			53
Natural gas (in mmbtu)
Ameren Missouri		6			8			(e	)		(e	)		16			9			22			19
Ameren Illinois		27			42			(e	)		(e	)		(e	)		(e	)		153			174
Genco		(e	)		(e	)		(e	)		(e	)		26			7			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		1			1			(e	)		(e	)
Ameren		33			50			(e	)		(e	)		43			17			175			193
Power (in megawatthours)
Ameren Missouri		4			1			(e	)		(e	)		1			1			13			6
Ameren Illinois		22			11			(e	)		(e	)		(e	)		(e	)		19			24
Genco		(e	)		(e	)		(e	)		(e	)		-			-			(e	)		(e	)
Other(f)		69			61			17			17			56			30			(4	)		(9	)
Ameren		95			73			17			17			57			31			28			21
Uranium (pounds in thousands)
Ameren Missouri & Ameren		5,361			5,553			(e	)		(e	)		(e	)		(e	)		131			148

(a) Contracts through December 2017, March 2015, September 2035, and October 2024 for coal, natural gas, power, and uranium, respectively, as of June 30, 2012.

(b) Contracts through December 2016 for power as of June 30, 2012.

(c) Contracts through December 2014, October 2016, April 2015, and December 2016 for coal, fuel oils, natural gas, and power, respectively, as of June 30, 2012.

(d) Contracts through October 2014, October 2016, May 2032, and December 2013 for fuel oils, natural gas, power, and uranium, respectively, as of June 30, 2012.

(e) Not applicable.

(f) Includes AERG contracts for coal and fuel oils, Marketing Company contracts for natural gas and power, and intercompany eliminations for power.

(g) Fuel oils consist of heating and crude oil.

Derivative Instruments Carrying Value

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
2012:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	23		$	(b	)	$	(b	)	$	(b	)
	Other assets		31			-			-			-
	Total assets	$	54		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	MTM derivative liabilities	$	1		$	(b	)	$	-		$	(b	)
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	13		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			8			-			4
	Other assets		5			4			-			1
Natural gas	MTM derivative assets		10			(b	)		(b	)		(b	)
	Other current assets		-			2			2			5
	Other assets		-			-			-			-
Power	MTM derivative assets		110			(b	)		(b	)		(b	)
	Other current assets		-			39			-			-
	Other assets		35			2			-			-
	Total assets	$	173		$	55		$	2		$	10
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Coal	MTM derivative liabilities	$	4		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			-			-			4
	Other deferred credits and liabilities		6			-			-			4
Fuel oils	MTM derivative liabilities		5			(b	)		-			(b	)
	Other current liabilities		-			2			-			2
	Other deferred credits and liabilities		6			2			-			3
Natural gas	MTM derivative liabilities		91			(b	)		78			(b	)
	Other current liabilities		-			12			-			1
	Other deferred credits and liabilities		77			11			66			-
Power	MTM derivative liabilities		96			(b	)		19			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		114			(b	)

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
	Other current liabilities	$	-		$	15		$	-		$	-
	Other deferred credits and liabilities		117			2			88			-
Uranium	MTM derivative liabilities		1			(b	)		-			(b	)
	Other current liabilities		-			1			-			-
	Total liabilities	$	403		$	45		$	365		$	14
2011:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	8		$	(b	)	$	(b	)	$	(b	)
	Other assets		16			-			-			-
	Total assets	$	24		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	Other deferred credits and liabilities	$	1		$	-		$	-		$	-
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	29		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			17			-			10
	Other assets		8			6			-			1
Natural gas	MTM derivative assets		6			(b	)		(b	)		(b	)
	Other current assets		-			2			1			2
	Other assets		-			-			1			-
Power	MTM derivative assets		72			(b	)		(b	)		(b	)
	Other current assets		-			30			-			-
	Other assets		99			-			77			-
	Total assets	$	214		$	55		$	79		$	13
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	2		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			1			-			1
Natural gas	MTM derivative liabilities		106			(b	)		90			(b	)
	Other current liabilities		-			13			-			2
	Other deferred credits and liabilities		92			13			79			-
Power	MTM derivative liabilities		53			(b	)		9			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		200			(b	)
	Other current liabilities		-			9			-			-
	Other deferred credits and liabilities		26			-			8			-
Uranium	Other deferred credits and liabilities		1			1			-			-
	Total liabilities	$	280		$	37		$	386		$	3

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

(b) Balance sheet line item not applicable to registrant.

(c) Includes derivatives subject to regulatory deferral.

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI

	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other (a)
2012:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	45		$	-		$	-		$	-		$	45
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		5			5			-			-			-
Natural gas derivative contracts(f)		(163	)		(21	)		(142	)		-			-
Power derivative contracts(g)		(82	)		24			(221	)		-			115
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-
2011:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	19		$	-		$	-		$	-		$	19
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		19			19			-			-			-
Natural gas derivative contracts(f)		(191	)		(24	)		(167	)		-			-
Power derivative contracts(g)		81			21			(140	)		-			200
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-

(a) Includes amounts for Marketing Company and intercompany eliminations.

(b) Represents net gains associated with power derivative contracts at Ameren. These contracts are a partial hedge of electricity price exposure through December 2016 as of June 30, 2012. Current gains of $17 million and $5 million were recorded at Ameren as of June 30, 2012, and December 31, 2011, respectively.

(c) Includes net gains associated with interest rate swaps at Genco that were a partial hedge of the interest rate on debt issued in June 2002. The swaps covered the first 10 years of debt that has a 30-year maturity, and the gain in OCI was amortized over a 10-year period that began in June 2002. The balance of the gain was fully amortized as of June 30, 2012. The carrying value at December 31, 2011, was less than $1 million.

(d) Includes net losses associated with interest rate swaps at Genco. The swaps were executed during the fourth quarter of 2007 as a partial hedge of interest rate risks associated with Genco’s April 2008 debt issuance. The loss on the interest rate swaps is being amortized over a 10-year period that began in April 2008. The carrying value at June 30, 2012, and December 31, 2011, was a loss of $8 million and $9 million, respectively. Over the next twelve months, $1.4 million of the loss will be amortized.

(e) Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2014 as of June 30, 2012. Current gains deferred as regulatory liabilities include $7 million and $7 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current gains deferred as regulatory liabilities include $16 million and $16 million at Ameren and Ameren Missouri as of December 31, 2011, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

(f) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2016 at Ameren, Ameren Missouri, and Ameren Illinois, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Illinois, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $88 million, $10 million, and $78 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $1 million and $1 million at Ameren and Ameren Illinois, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $101 million, $11 million, and $90 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(g) Represents net losses associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $37 million and $37 million at Ameren and Ameren Missouri, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $33 million, $14 million, and $133 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $29 million and $29 million at Ameren and Ameren Missouri, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $17 million, $8 million, and $209 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(h) Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of our uranium requirements through December 2013 as of June 30, 2012. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include less than $1 million and less than $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

Maximum Exposure If Counterparties Fail To Perform On Contracts

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	1	$	1	$	2	$	6	$	15	$	4		$	-	$	-	$	29
AIC		-		-		1		-		1		-			-		-		2
	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
Genco	$	-	$	-	$	2	$	-	$	1	$	-		$	3	$	-	$	6
Other(b)		187		10		46		14		18		465	(c)		1		103		844
Ameren	$	188	$	11	$	51	$	20	$	35	$	469		$	4	$	103	$	881
2011:
AMO	$	1	$	35	$	1	$	4	$	26	$	4		$	-	$	-	$	71
AIC		-		-		84		-		1		-			-		-		85
Genco		-		1		1		2		6		-			3		-		13
Other(b)		275		1		3		10		51		194	(c)		-		87		621
Ameren	$	276	$	37	$	89	$	16	$	84	$	198		$	3	$	87	$	790

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Potential Loss On Counterparty Exposures

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	-	$	-	$	2	$	2	$	8	$	4		$	-	$	-	$	16
AIC		-		-		1		-		-		-			-		-		1
Genco		-		-		1		-		-		-			1		-		2
Other(b)		186		5		38		3		13		459	(c)		-		102		806
Ameren	$	186	$	5	$	42	$	5	$	21	$	463		$	1	$	102	$	825
2011:
AMO	$	1	$	35	$	1	$	3	$	22	$	4		$	-	$	-	$	66
AIC		-		-		84		-		-		-			-		-		84
Genco		-		-		-		1		1		-			2		-		4
Other(b)		273		-		3		5		42		187	(c)		-		86		596
Ameren	$	274	$	35	$	88	$	9	$	65	$	191		$	2	$	86	$	750

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Derivative Instruments With Credit Risk-Related Contingent Features

	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional  Collateral Required(b)
2012:
Ameren Missouri	$	146	$	7	$	125
Ameren Illinois		174		91		106
Genco		48		1		41
Other(c)		86		12		63
Ameren	$	454	$	111	$	335
2011:
Ameren Missouri	$	102	$	8	$	86
Ameren Illinois		220		96		125
Genco		55		1		58
Other(c)		79		11		63
Ameren	$	456	$	116	$	332

(a) Prior to consideration of master trading and netting agreements and including NPNS contract exposures.

(b) As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is after consideration of the effects of such agreements.

(c) Includes amounts for Marketing Company and Ameren (parent).

Derivatives That Qualify For Regulatory Deferral

		Gain (Loss) Recognized in Regulatory  Liabilities or Regulatory Assets
		Three Months						Six Months
		2012			2011			2012			2011
Ameren(a)	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		46			3			28			34
	Power		(1	)		88			(163	)		90
	Uranium		-			(3	)		-			(4	)
	Total	$	26		$	75		$	(149	)	$	136
Ameren Missouri	Fuel oils	$	(19	)	$	(13	)	$	(14	)	$	16
	Natural gas		5			1			3			4
	Power		4			23			3			23
	Uranium		-			(3	)		-			(4	)
	Total	$	(10	)	$	8		$	(8	)	$	39
Ameren Illinois	Natural gas	$	41		$	2		$	25		$	30
	Power		63			121			(81	)		148
	Total	$	104		$	123		$	(56	)	$	178

(a) Includes amounts for intercompany eliminations.

Ameren Energy Generating Company [Member]

Open Gross Derivative Volumes By Commodity Type

	Quantity (in millions, except as indicated)
Commodity	NPNS Contracts(a)						Cash Flow Hedges(b)						Other Derivatives(c)						Derivatives That Qualify for Regulatory Deferral(d)
	2012			2011			2012			2011			2012			2011			2012			2011
Coal (in tons)
Ameren Missouri		106			116			(e	)		(e	)		-			(e	)		(e	)		(e	)
Genco		31			24			(e	)		(e	)		5			(e	)		(e	)		(e	)
Other(f)		9			7			(e	)		(e	)		1			(e	)		(e	)		(e	)
Ameren		146			147			(e	)		(e	)		6			(e	)		(e	)		(e	)
Fuel oils (in gallons)(g)
Ameren Missouri		(e	)		(e	)		(e	)		(e	)		(e	)		(e	)		59			53
Genco		(e	)		(e	)		(e	)		(e	)		43			27			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		12			9			(e	)		(e	)
Ameren		(e	)		(e	)		(e	)		(e	)		55			36			59			53
Natural gas (in mmbtu)
Ameren Missouri		6			8			(e	)		(e	)		16			9			22			19
Ameren Illinois		27			42			(e	)		(e	)		(e	)		(e	)		153			174
Genco		(e	)		(e	)		(e	)		(e	)		26			7			(e	)		(e	)
Other(f)		(e	)		(e	)		(e	)		(e	)		1			1			(e	)		(e	)
Ameren		33			50			(e	)		(e	)		43			17			175			193
Power (in megawatthours)
Ameren Missouri		4			1			(e	)		(e	)		1			1			13			6
Ameren Illinois		22			11			(e	)		(e	)		(e	)		(e	)		19			24
Genco		(e	)		(e	)		(e	)		(e	)		-			-			(e	)		(e	)
Other(f)		69			61			17			17			56			30			(4	)		(9	)
Ameren		95			73			17			17			57			31			28			21
Uranium (pounds in thousands)
Ameren Missouri & Ameren		5,361			5,553			(e	)		(e	)		(e	)		(e	)		131			148

(a) Contracts through December 2017, March 2015, September 2035, and October 2024 for coal, natural gas, power, and uranium, respectively, as of June 30, 2012.

(b) Contracts through December 2016 for power as of June 30, 2012.

(c) Contracts through December 2014, October 2016, April 2015, and December 2016 for coal, fuel oils, natural gas, and power, respectively, as of June 30, 2012.

(d) Contracts through October 2014, October 2016, May 2032, and December 2013 for fuel oils, natural gas, power, and uranium, respectively, as of June 30, 2012.

(e) Not applicable.

(f) Includes AERG contracts for coal and fuel oils, Marketing Company contracts for natural gas and power, and intercompany eliminations for power.

(g) Fuel oils consist of heating and crude oil.

Derivative Instruments Carrying Value

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
2012:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	23		$	(b	)	$	(b	)	$	(b	)
	Other assets		31			-			-			-
	Total assets	$	54		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	MTM derivative liabilities	$	1		$	(b	)	$	-		$	(b	)
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	13		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			8			-			4
	Other assets		5			4			-			1
Natural gas	MTM derivative assets		10			(b	)		(b	)		(b	)
	Other current assets		-			2			2			5
	Other assets		-			-			-			-
Power	MTM derivative assets		110			(b	)		(b	)		(b	)
	Other current assets		-			39			-			-
	Other assets		35			2			-			-
	Total assets	$	173		$	55		$	2		$	10
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Coal	MTM derivative liabilities	$	4		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			-			-			4
	Other deferred credits and liabilities		6			-			-			4
Fuel oils	MTM derivative liabilities		5			(b	)		-			(b	)
	Other current liabilities		-			2			-			2
	Other deferred credits and liabilities		6			2			-			3
Natural gas	MTM derivative liabilities		91			(b	)		78			(b	)
	Other current liabilities		-			12			-			1
	Other deferred credits and liabilities		77			11			66			-
Power	MTM derivative liabilities		96			(b	)		19			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		114			(b	)

	Balance Sheet Location	Ameren(a)			Ameren Missouri			Ameren Illinois			Genco
	Other current liabilities	$	-		$	15		$	-		$	-
	Other deferred credits and liabilities		117			2			88			-
Uranium	MTM derivative liabilities		1			(b	)		-			(b	)
	Other current liabilities		-			1			-			-
	Total liabilities	$	403		$	45		$	365		$	14
2011:
Derivative assets designated as hedging instruments
Commodity contracts:
Power	MTM derivative assets	$	8		$	(b	)	$	(b	)	$	(b	)
	Other assets		16			-			-			-
	Total assets	$	24		$	-		$	-		$	-
Derivative liabilities designated as hedging instruments
Commodity contracts:
Power	Other deferred credits and liabilities	$	1		$	-		$	-		$	-
	Total liabilities	$	1		$	-		$	-		$	-
Derivative assets not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative assets	$	29		$	(b	)	$	(b	)	$	(b	)
	Other current assets		-			17			-			10
	Other assets		8			6			-			1
Natural gas	MTM derivative assets		6			(b	)		(b	)		(b	)
	Other current assets		-			2			1			2
	Other assets		-			-			1			-
Power	MTM derivative assets		72			(b	)		(b	)		(b	)
	Other current assets		-			30			-			-
	Other assets		99			-			77			-
	Total assets	$	214		$	55		$	79		$	13
Derivative liabilities not designated as hedging instruments(c)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	2		$	(b	)	$	-		$	(b	)
	Other current liabilities		-			1			-			1
Natural gas	MTM derivative liabilities		106			(b	)		90			(b	)
	Other current liabilities		-			13			-			2
	Other deferred credits and liabilities		92			13			79			-
Power	MTM derivative liabilities		53			(b	)		9			(b	)
	MTM derivative liabilities - affiliates		(b	)		(b	)		200			(b	)
	Other current liabilities		-			9			-			-
	Other deferred credits and liabilities		26			-			8			-
Uranium	Other deferred credits and liabilities		1			1			-			-
	Total liabilities	$	280		$	37		$	386		$	3

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

(b) Balance sheet line item not applicable to registrant.

(c) Includes derivatives subject to regulatory deferral.

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI

	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other (a)
2012:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	45		$	-		$	-		$	-		$	45
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		5			5			-			-			-
Natural gas derivative contracts(f)		(163	)		(21	)		(142	)		-			-
Power derivative contracts(g)		(82	)		24			(221	)		-			115
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-
2011:
Cumulative gains (losses) deferred in accumulated OCI:
Power derivative contracts(b)	$	19		$	-		$	-		$	-		$	19
Interest rate derivative contracts(c)(d)		(8	)		-			-			(8	)		-
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(e)		19			19			-			-			-
Natural gas derivative contracts(f)		(191	)		(24	)		(167	)		-			-
Power derivative contracts(g)		81			21			(140	)		-			200
Uranium derivative contracts(h)		(1	)		(1	)		-			-			-

(a) Includes amounts for Marketing Company and intercompany eliminations.

(b) Represents net gains associated with power derivative contracts at Ameren. These contracts are a partial hedge of electricity price exposure through December 2016 as of June 30, 2012. Current gains of $17 million and $5 million were recorded at Ameren as of June 30, 2012, and December 31, 2011, respectively.

(c) Includes net gains associated with interest rate swaps at Genco that were a partial hedge of the interest rate on debt issued in June 2002. The swaps covered the first 10 years of debt that has a 30-year maturity, and the gain in OCI was amortized over a 10-year period that began in June 2002. The balance of the gain was fully amortized as of June 30, 2012. The carrying value at December 31, 2011, was less than $1 million.

(d) Includes net losses associated with interest rate swaps at Genco. The swaps were executed during the fourth quarter of 2007 as a partial hedge of interest rate risks associated with Genco’s April 2008 debt issuance. The loss on the interest rate swaps is being amortized over a 10-year period that began in April 2008. The carrying value at June 30, 2012, and December 31, 2011, was a loss of $8 million and $9 million, respectively. Over the next twelve months, $1.4 million of the loss will be amortized.

(e) Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2014 as of June 30, 2012. Current gains deferred as regulatory liabilities include $7 million and $7 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current gains deferred as regulatory liabilities include $16 million and $16 million at Ameren and Ameren Missouri as of December 31, 2011, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

(f) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2016 at Ameren, Ameren Missouri, and Ameren Illinois, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Illinois, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $88 million, $10 million, and $78 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $1 million and $1 million at Ameren and Ameren Illinois, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $101 million, $11 million, and $90 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(g) Represents net losses associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of June 30, 2012. Current gains deferred as regulatory liabilities include $37 million and $37 million at Ameren and Ameren Missouri, respectively, as of June 30, 2012. Current losses deferred as regulatory assets include $33 million, $14 million, and $133 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of June 30, 2012. Current gains deferred as regulatory liabilities include $29 million and $29 million at Ameren and Ameren Missouri, respectively, as of December 31, 2011. Current losses deferred as regulatory assets include $17 million, $8 million, and $209 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2011.

(h) Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of our uranium requirements through December 2013 as of June 30, 2012. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of June 30, 2012, respectively. Current losses deferred as regulatory assets include less than $1 million and less than $1 million at Ameren and Ameren Missouri as of December 31, 2011, respectively.

Maximum Exposure If Counterparties Fail To Perform On Contracts

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	1	$	1	$	2	$	6	$	15	$	4		$	-	$	-	$	29
AIC		-		-		1		-		1		-			-		-		2
	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
Genco	$	-	$	-	$	2	$	-	$	1	$	-		$	3	$	-	$	6
Other(b)		187		10		46		14		18		465	(c)		1		103		844
Ameren	$	188	$	11	$	51	$	20	$	35	$	469		$	4	$	103	$	881
2011:
AMO	$	1	$	35	$	1	$	4	$	26	$	4		$	-	$	-	$	71
AIC		-		-		84		-		1		-			-		-		85
Genco		-		1		1		2		6		-			3		-		13
Other(b)		275		1		3		10		51		194	(c)		-		87		621
Ameren	$	276	$	37	$	89	$	16	$	84	$	198		$	3	$	87	$	790

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Potential Loss On Counterparty Exposures

	Affiliates(a)		Coal Producers		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives			Oil and Gas Companies		Retail Companies		Total
2012:
AMO	$	-	$	-	$	2	$	2	$	8	$	4		$	-	$	-	$	16
AIC		-		-		1		-		-		-			-		-		1
Genco		-		-		1		-		-		-			1		-		2
Other(b)		186		5		38		3		13		459	(c)		-		102		806
Ameren	$	186	$	5	$	42	$	5	$	21	$	463		$	1	$	102	$	825
2011:
AMO	$	1	$	35	$	1	$	3	$	22	$	4		$	-	$	-	$	66
AIC		-		-		84		-		-		-			-		-		84
Genco		-		-		-		1		1		-			2		-		4
Other(b)		273		-		3		5		42		187	(c)		-		86		596
Ameren	$	274	$	35	$	88	$	9	$	65	$	191		$	2	$	86	$	750

(a) Primarily comprised of Marketing Company’s exposure to Ameren Illinois related to financial contracts. The exposure is not eliminated at the consolidated Ameren level for purposes of this disclosure, as it is calculated without regard to the offsetting affiliate counterparty’s liability position. See Note 14 - Related Party Transactions in the Form 10-K for additional information on these financial contracts.

(b) Includes amounts for Marketing Company, AERG, and AFS.

(c) Primarily composed of Marketing Company’s exposure to NPNS contracts with terms through September 2035.

Derivative Instruments With Credit Risk-Related Contingent Features

	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional  Collateral Required(b)
2012:
Ameren Missouri	$	146	$	7	$	125
Ameren Illinois		174		91		106
Genco		48		1		41
Other(c)		86		12		63
Ameren	$	454	$	111	$	335
2011:
Ameren Missouri	$	102	$	8	$	86
Ameren Illinois		220		96		125
Genco		55		1		58
Other(c)		79		11		63
Ameren	$	456	$	116	$	332

(a) Prior to consideration of master trading and netting agreements and including NPNS contract exposures.

(b) As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is after consideration of the effects of such agreements.

(c) Includes amounts for Marketing Company and Ameren (parent).

Cash Flow Hedges

	Gain (Loss) Recognized in OCI(a)			Location of (Gain) Loss Reclassified from OCI into Income(b)	(Gain) Loss Reclassified from OCI into Income(b)			Location of Gain (Loss) Recognized in Income(c)	Gain (Loss) Recognized in Income(c)
Three Months
2012:
Ameren:(d)
Power	$	5		Operating Revenues - Electric	$	2		Operating Revenues - Electric	$	(1	)
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
2011:
Ameren:(d)
Power	$	(3	)	Operating Revenues - Electric	$	1		Operating Revenues - Electric	$	3
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Six Months
2012:
Ameren:(d)
Power	$	23		Operating Revenues - Electric	$	6		Operating Revenues - Electric	$	1
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
2011:
Ameren:(d)
Power	$	(7	)	Operating Revenues - Electric	$	2		Operating Revenues - Electric	$	2
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-
Genco:
Interest rate(e)		-		Interest Charges		(f	)	Interest Charges		-

(a) Effective portion of gain (loss).

(b) Effective portion of (gain) loss on settlements.

(c) Ineffective portion of gain (loss) and amount excluded from effectiveness testing.

(d) Includes amounts from Ameren registrant and nonregistrant subsidiaries.

(e) Represents interest rate swaps settled in prior periods. The cumulative gain and loss on the interest rate swaps is being amortized into income over a 10-year period.

(f) Less than $1 million.

Other Derivatives

		Location of Gain (Loss) Recognized in Income	Gain (Loss) Recognized in Income
			Three Months						Six Months
			2012			2011			2012			2011
Ameren(a)	Coal	Operating Expenses - Fuel	$	(6	)	$	-		$	(10	)	$	-
	Fuel oils	Operating Expenses - Fuel		(18	)		(9	)		(13	)		10
	Natural gas (generation)	Operating Expenses - Fuel		4			-			5			-
	Power	Operating Revenues - Electric		7			(5	)		6			(7	)
		Total	$	(13	)	$	(14	)	$	(12	)	$	3
Ameren Missouri	Natural gas (generation)	Operating Expenses - Fuel	$	-		$	-		$	-		$	(1	)
Genco	Coal	Operating Expenses - Fuel	$	(5	)	$	-		$	(8	)	$	-
	Fuel oils	Operating Expenses - Fuel		(14	)		(8	)		(10	)		7
	Natural gas (generation)	Operating Expenses - Fuel		4			-			4			-
	Power	Operating Revenues		-			(1	)		-			(1	)
		Total	$	(15	)	$	(9	)	$	(14	)	$	6

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