Retirement Benefits

12 Months Ended

Dec. 31, 2011

Retirement Benefits

NOTE 11 – RETIREMENT BENEFITS

The primary objective of the Ameren pension plans and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offers defined benefit pension and postretirement benefit plans covering substantially all of its employees. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren Missouri, Ameren Illinois and Genco, excluding EEI, each participate in Ameren's single-employer pension and other postretirement plans. Ameren's qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded non-qualified pension plan, the Ameren Supplemental Retirement Plan, which is available for certain management employees and retirees to provide a supplemental benefit when their qualified pension plan benefits are reduced to comply with Internal Revenue Code limitations. Ameren's other postretirement plans are the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. Separately, EEI employees and retirees participate in EEI's single-employer pension and other postretirement plans. EEI's pension plan is the Revised Retirement Plan for Employees of Electric Energy, Inc. EEI's other postretirement plans are the Group Insurance Plan for Management Employees of Electric Energy, Inc. and the Group Insurance Plan for Bargaining Unit Employees of Electric Energy, Inc. Nonaffiliated Ameren companies do not participate in the Ameren Retirement Plan, the Ameren Supplemental Retirement Plan, the Ameren Retiree Medical Plan, and the Ameren Group Life Insurance Plan. Ameren and Genco each consolidate EEI, and therefore, EEI's plans are reflected in Ameren's and Genco's pension and postretirement balances and disclosures.

The following table presents the benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2011:

Ameren(a)	$	1,350
Ameren Missouri		494
Ameren Illinois		496
Genco		141

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

Ameren recognizes the underfunded status of its pension and postretirement plans as a liability on its balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance. The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2011, and 2010. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2011, and 2010, that have not been recognized in net periodic benefit costs.

	2011						2010
	Pension Benefits(a)			Postretirement Benefits(a)			Pension Benefits(a)			Postretirement Benefits(a)
Accumulated benefit obligation at end of year	$	3,645		$	(b	)	$	3,246		$	(b	)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	3,451		$	1,120		$	3,255		$	1,143
Service cost		75			22			68			20
Interest cost		180			58			185			62
Plan amendments(c)(d)		(16	)		-			(40	)		-
Participant contributions		-			18			-			17
Actuarial (gain) loss		348			96			165			(53	)
Benefits paid		(173	)		(66	)		(182	)		(74	)
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Net benefit obligation at end of year		3,865			1,257			3,451			1,120
Change in plan assets:
Fair value of plan assets at beginning of year		2,722			797			2,495			732
Actual return on plan assets		224			9			328			81
Employer contributions		103			129			81			36
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Participant contributions		-			18			-			17
Benefits paid		(173	)		(66	)		(182	)		(74	)
Fair value of plan assets at end of year		2,876			896			2,722			797
Funded status – deficiency		989			361			729			323
Accrued benefit cost at December 31	$	989		$	361		$	729		$	323
Amounts recognized in the balance sheet consist of:
Current liability	$	3		$	3		$	4		$	3
Noncurrent liability		986			358			725			320
Total	$	989		$	361		$	729		$	323
Amounts recognized in regulatory assets consist of:
Net actuarial loss	$	734		$	177		$	507		$	86
Prior service cost (credit)		(7	)		(28	)		(11	)		(32	)
Transition obligation		-			2			-			5
Amounts (pretax) recognized in accumulated OCI consist of:
Net actuarial loss		79			43			24			13
Prior service cost (credit)		(15	)		(7	)		4			(10	)
Total	$	791		$	187		$	524		$	62

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

(b) Not applicable.

(c) In 2011, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 430 labor union-represented employees from a traditional, final pay formula to a cash balance formula.

(d) In 2010, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 700 management employees from a traditional, final pay formula to a cash balance formula.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2011, and 2010:

	Pension Benefits						Postretirement Benefits
	2011			2010			2011			2010
Discount rate at measurement date		4.50	%		5.25	%		4.50	%		5.25	%
Increase in future compensation		3.50			3.50			3.50			3.50
Medical cost trend rate (initial)		-			-			5.50			6.00
Medical cost trend rate (ultimate)		-			-			5.00			5.00
Years to ultimate rate		-			-			10 year			2 years

Ameren determines discount rate assumptions by using an interest rate yield curve pursuant to authoritative accounting guidance on the determination of discount rates used for defined benefit plan obligations. The yield curve is based on the yields of more than 500 high-quality corporate bonds with maturities between zero and 30 years. A theoretical spot-rate curve constructed from this yield curve is then used as a guide to develop a discount rate matching the plans' payout structure.

Funding

Pension benefits are based on the employees' years of service and compensation. Ameren's pension plan is funded in compliance with income tax regulations and federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren's assumptions at December 31, 2011, its investment performance in 2011, and its pension funding policy, Ameren expects to make annual contributions of $90 million to $150 million in each of the next five years, with aggregate estimated contributions of $580 million. We expect Ameren Missouri's, Ameren Illinois' and Genco's portion of the future funding requirements to be 51%, 33%, and 12%, respectively. These amounts are estimates. The estimates may change based on actual investment performance, changes in interest rates, changes in our assumptions, any pertinent changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2011, 2010, and 2009:

	Pension Benefits						Postretirement Benefits
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	103	$	81	$	99	$	129	$	36	$	49
AMO		43		36		42		9		11		13
AIC		28		23		25		118		20		28
Genco		12		4		10		-		-		-

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

Investment Strategy and Policies

Ameren manages plan assets in accordance with the "prudent investor" guidelines contained in ERISA. The investment committee, to the extent authority is delegated to it by the finance committee of Ameren's board of directors, implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee's goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable, and second, to maximize total return on plan assets and minimize expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists in each asset class. As appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.

The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will utilize an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.75% and 7.50%, respectively, in 2012. No plan assets are expected to be returned to Ameren during 2012.

Ameren's investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value) and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee's strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 2012 and our pension and postretirement plans' asset categories as of December 31, 2011, and 2010.

				Percentage of Plan Assets at December  31,
Asset Category	Target Allocation 2012			2011			2010
Pension Plan:
Cash and cash equivalents		0  - 5	%		2	%		1	%
Equity securities:
U.S. large capitalization		29 - 39			33			31
U.S. small and mid-capitalization		2 - 12			7			11
International and emerging markets		9 - 19			11			15
Total equity		50 - 60			51			57
Debt securities		35 - 45			42			37
Real estate		0 - 9			4			4
Private equity		0 - 4			1			1
Total					100	%		100	%
Postretirement Plans:
Cash and cash equivalents		0 - 10	%		4	%		4	%
Equity securities:
U.S. large capitalization		33 - 43			38			39
U.S. small and mid-capitalization		3 - 13			8			10
International		10 - 20			13			14
Total equity		55 - 65			59			63
Debt securities		30 - 40			37			33
Total					100	%		100	%

In general, the U.S. large capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, U.S. small capitalization, and U.S. mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-U.S. dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren's investment in private equity funds consists of 10 different limited partnerships, with invested capital ranging from $0.1 million to $7 million each, which invest primarily in a diversified number of small U.S.-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren's investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations, to increase or to reduce market exposure in an efficient and timely manner.

Fair Value Measurements of Plan Assets

Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2011. The fair value of an asset is the amount that would be received upon sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the last business day on or before the measurement date. Securities traded in over-the-counter markets are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	31	$	-	$	31
Equity securities:
U.S. large capitalization		72			922		-		994
U.S. small and mid-capitalization		202			11		-		213
International and emerging markets		115			213		-		328
Debt securities:
Corporate bonds		-			720		-		720
Municipal bonds		-			176		-		176
U.S. treasury and agency securities		-			230		-		230
Other		-			121		-		121
Real estate		-			-		108		108
Private equity		-			-		23		23
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	389		$	2,424	$	131	$	2,944
Less: Medical benefit assets at December 31(a)									(91	)
Plus: Net receivables at December 31(b)									23
Fair value of pension plans assets at year end								$	2,876

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	20	$	-	$	20
Equity securities:
U.S. large capitalization		70			812		-		882
U.S. small and mid-capitalization		299			10		-		309
International and emerging markets		129			284		-		413
Debt securities:
Corporate bonds		-			646		-		646
Municipal bonds		-			129		-		129
U.S. treasury and agency securities		-			154		-		154
Other		-			100		-		100
Real estate		-			-		98		98
Private equity		-			-		28		28
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	498		$	2,155	$	126	$	2,779
Less: Medical benefit assets at December 31(a)									(85	)
Plus: Net receivables at December 31(b)									28
Fair value of pension plans assets at year end								$	2,722

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2011, and 2010:

	Beginning Balance at January 1,		Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date			Actual Return on Plan Assets Related to Assets Sold During the Period		Purchases, Sales, and Settlements, net			Net Transfers into (out of) of Level 3		Ending Balance at December 31,
2011:
Real estate	$	98	$	10		$	-	$	-		$	-	$	108
Private equity		28		(10	)		11		(6	)		-		23
2010:
Other debt securities	$	1	$	-		$	-	$	(1	)	$	-	$	-
Real estate		90		7			-		1			-		98
Private equity		33		(5	)		7		(7	)		-		28

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1	$	66	$	-	$	67
Equity securities:
U.S. large capitalization		235		78		-		313
U.S. small and mid-capitalization		57		-		-		57
International		44		56		-		100
Debt securities:
Corporate bonds		-		61		-		61
Municipal bonds		-		86		-		86
U.S. treasury and agency securities		-		82		-		82
Asset-backed securities		-		23		-		23
Other		-		49		-		49
Total	$	337	$	501	$	-	$	838
Plus: Medical benefit assets at December 31(a)								91
Less: Net payables at December 31(b)								(33	)
Fair value of postretirement benefit plans assets at year end							$	896

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-	$	35	$	-	$	35
Equity securities:
U.S. large capitalization		215		72		-		287
U.S. small and mid-capitalization		66		-		-		66
International		43		51		-		94
Debt securities:
Corporate bonds		-		59		-		59
Municipal bonds		-		58		-		58
U.S. treasury and agency securities		-		59		-		59
Asset-backed securities		-		31		-		31
Other		-		29		-		29
Total	$	324	$	394	$	-	$	718
Plus: Medical benefit assets at December 31(a)								85
Less: Net payables at December 31(b)								(6	)
Fair value of postretirement benefit plans assets at year end							$	797

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2011, 2010, and 2009:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
2011:
Service cost	$	75		$	22
Interest cost		180			58
Expected return on plan assets		(216	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		(1	)		(8	)
Actuarial loss		42			5
Net periodic benefit cost	$	80		$	25
2010:
Service cost	$	68		$	20
Interest cost		185			62
Expected return on plan assets		(212	)		(56	)
Amortization of:
Transition obligation		-			2
Prior service cost		6			(8	)
Actuarial loss		18			1
Net periodic benefit cost	$	65		$	21
2009:
Service cost	$	68		$	19
Interest cost		186			66
Expected return on plan assets		(206	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		9			(8	)
Actuarial loss		24			9
Net periodic benefit cost	$	81		$	34

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

The current year expected return on plan assets is determined primarily by adjusting the prior-year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.

The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2012 are as follows:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
Regulatory assets:
Transition obligation	$	-		$	2
Prior service cost (credit)		(1	)		(4	)
Net actuarial loss		87			23
Accumulated OCI:
Transition obligation		-			-
Prior service cost (credit)		(1	)		(1	)
Net actuarial loss		6			3
Total	$	91		$	23

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

Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The net actuarial loss subject to amortization is amortized on a straight-line basis over 10 years.

Ameren Missouri, Ameren Illinois and Genco are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred for the years ended December 31, 2011, 2010, and 2009:

	Pension Costs						Postretirement Costs
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	80	$	65	$	81	$	25	$	21	$	34
Ameren Missouri		51		42		50		11		11		15
Ameren Illinois		16		10		14		11		7		16
Genco		8		9		11		3		2		3

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

The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2011, are as follows:

	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust		Paid from Company Funds		Paid from Qualified Trust		Paid from Company Funds		Federal Subsidy
2012		223		3		68		3		5
2013		225		3		71		3		5
2014		230		3		74		3		5
2015		231		3		77		3		6
2016		232		3		80		3		6
2017 - 2021		1,167		12		443		14		32

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2011, 2010, and 2009:

	Pension Benefits									Postretirement Benefits
	2011			2010			2009			2011			2010			2009
Discount rate at measurement date		5.25	%		5.75	%		5.75	%		5.25	%		5.75	%		5.75	%
Expected return on plan assets		8.00			8.00			8.00			7.75			8.00			8.00
Increase in future compensation		3.50			3.50			4.00			3.50			3.50			4.00
Medical cost trend rate (initial)		-			-			-			6.00			6.50			7.00
Medical cost trend rate (ultimate)		-			-			-			5.00			5.00			5.00
Years to ultimate rate		-			-			-			2 years			3 years			4 years

The table below reflects the sensitivity of Ameren's plans to potential changes in key assumptions:

	Pension Benefits					Postretirement Benefits
	Service Cost and Interest Cost			Projected Benefit Obligation		Service Cost and Interest Cost			Postretirement Benefit Obligation
0.25% decrease in discount rate	$	(2	)	$	110	$	-		$	38
0.25% increase in salary scale		2			14		-			-
1.00% increase in annual medical trend		-			-		3			42
1.00% decrease in annual medical trend		-			-		(3	)		(41	)

Other

Ameren sponsors a 401(k) plan for eligible employees. The Ameren plan covered all eligible employees of the Ameren Companies at December 31, 2011. The plans allowed employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matched a percentage of the employee contributions up to certain limits. The following table presents the portion of the 401(k) matching contribution to the Ameren plan attributable to each of the Ameren Companies for the years ended December 31, 2011, 2010, and 2009:

	2011		2010		2009
Ameren(a)	$	28	$	27	$	24
Ameren Missouri		16		16		14
Ameren Illinois		8		8		7
Genco		2		1		2

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

Ameren Illinois Company [Member]

Retirement Benefits

NOTE 11 – RETIREMENT BENEFITS

The primary objective of the Ameren pension plans and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offers defined benefit pension and postretirement benefit plans covering substantially all of its employees. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren Missouri, Ameren Illinois and Genco, excluding EEI, each participate in Ameren's single-employer pension and other postretirement plans. Ameren's qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded non-qualified pension plan, the Ameren Supplemental Retirement Plan, which is available for certain management employees and retirees to provide a supplemental benefit when their qualified pension plan benefits are reduced to comply with Internal Revenue Code limitations. Ameren's other postretirement plans are the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. Separately, EEI employees and retirees participate in EEI's single-employer pension and other postretirement plans. EEI's pension plan is the Revised Retirement Plan for Employees of Electric Energy, Inc. EEI's other postretirement plans are the Group Insurance Plan for Management Employees of Electric Energy, Inc. and the Group Insurance Plan for Bargaining Unit Employees of Electric Energy, Inc. Nonaffiliated Ameren companies do not participate in the Ameren Retirement Plan, the Ameren Supplemental Retirement Plan, the Ameren Retiree Medical Plan, and the Ameren Group Life Insurance Plan. Ameren and Genco each consolidate EEI, and therefore, EEI's plans are reflected in Ameren's and Genco's pension and postretirement balances and disclosures.

The following table presents the benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2011:

Ameren(a)	$	1,350
Ameren Missouri		494
Ameren Illinois		496
Genco		141

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

Ameren recognizes the underfunded status of its pension and postretirement plans as a liability on its balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance. The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2011, and 2010. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2011, and 2010, that have not been recognized in net periodic benefit costs.

	2011						2010
	Pension Benefits(a)			Postretirement Benefits(a)			Pension Benefits(a)			Postretirement Benefits(a)
Accumulated benefit obligation at end of year	$	3,645		$	(b	)	$	3,246		$	(b	)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	3,451		$	1,120		$	3,255		$	1,143
Service cost		75			22			68			20
Interest cost		180			58			185			62
Plan amendments(c)(d)		(16	)		-			(40	)		-
Participant contributions		-			18			-			17
Actuarial (gain) loss		348			96			165			(53	)
Benefits paid		(173	)		(66	)		(182	)		(74	)
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Net benefit obligation at end of year		3,865			1,257			3,451			1,120
Change in plan assets:
Fair value of plan assets at beginning of year		2,722			797			2,495			732
Actual return on plan assets		224			9			328			81
Employer contributions		103			129			81			36
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Participant contributions		-			18			-			17
Benefits paid		(173	)		(66	)		(182	)		(74	)
Fair value of plan assets at end of year		2,876			896			2,722			797
Funded status – deficiency		989			361			729			323
Accrued benefit cost at December 31	$	989		$	361		$	729		$	323
Amounts recognized in the balance sheet consist of:
Current liability	$	3		$	3		$	4		$	3
Noncurrent liability		986			358			725			320
Total	$	989		$	361		$	729		$	323
Amounts recognized in regulatory assets consist of:
Net actuarial loss	$	734		$	177		$	507		$	86
Prior service cost (credit)		(7	)		(28	)		(11	)		(32	)
Transition obligation		-			2			-			5
Amounts (pretax) recognized in accumulated OCI consist of:
Net actuarial loss		79			43			24			13
Prior service cost (credit)		(15	)		(7	)		4			(10	)
Total	$	791		$	187		$	524		$	62

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

(b) Not applicable.

(c) In 2011, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 430 labor union-represented employees from a traditional, final pay formula to a cash balance formula.

(d) In 2010, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 700 management employees from a traditional, final pay formula to a cash balance formula.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2011, and 2010:

	Pension Benefits						Postretirement Benefits
	2011			2010			2011			2010
Discount rate at measurement date		4.50	%		5.25	%		4.50	%		5.25	%
Increase in future compensation		3.50			3.50			3.50			3.50
Medical cost trend rate (initial)		-			-			5.50			6.00
Medical cost trend rate (ultimate)		-			-			5.00			5.00
Years to ultimate rate		-			-			10 year			2 years

Ameren determines discount rate assumptions by using an interest rate yield curve pursuant to authoritative accounting guidance on the determination of discount rates used for defined benefit plan obligations. The yield curve is based on the yields of more than 500 high-quality corporate bonds with maturities between zero and 30 years. A theoretical spot-rate curve constructed from this yield curve is then used as a guide to develop a discount rate matching the plans' payout structure.

Funding

Pension benefits are based on the employees' years of service and compensation. Ameren's pension plan is funded in compliance with income tax regulations and federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren's assumptions at December 31, 2011, its investment performance in 2011, and its pension funding policy, Ameren expects to make annual contributions of $90 million to $150 million in each of the next five years, with aggregate estimated contributions of $580 million. We expect Ameren Missouri's, Ameren Illinois' and Genco's portion of the future funding requirements to be 51%, 33%, and 12%, respectively. These amounts are estimates. The estimates may change based on actual investment performance, changes in interest rates, changes in our assumptions, any pertinent changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2011, 2010, and 2009:

	Pension Benefits						Postretirement Benefits
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	103	$	81	$	99	$	129	$	36	$	49
AMO		43		36		42		9		11		13
AIC		28		23		25		118		20		28
Genco		12		4		10		-		-		-

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

Investment Strategy and Policies

Ameren manages plan assets in accordance with the "prudent investor" guidelines contained in ERISA. The investment committee, to the extent authority is delegated to it by the finance committee of Ameren's board of directors, implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee's goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable, and second, to maximize total return on plan assets and minimize expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists in each asset class. As appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.

The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will utilize an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.75% and 7.50%, respectively, in 2012. No plan assets are expected to be returned to Ameren during 2012.

Ameren's investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value) and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee's strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 2012 and our pension and postretirement plans' asset categories as of December 31, 2011, and 2010.

				Percentage of Plan Assets at December  31,
Asset Category	Target Allocation 2012			2011			2010
Pension Plan:
Cash and cash equivalents		0  - 5	%		2	%		1	%
Equity securities:
U.S. large capitalization		29 - 39			33			31
U.S. small and mid-capitalization		2 - 12			7			11
International and emerging markets		9 - 19			11			15
Total equity		50 - 60			51			57
Debt securities		35 - 45			42			37
Real estate		0 - 9			4			4
Private equity		0 -4			1			1
Total					100	%		100	%
Postretirement Plans:
Cash and cash equivalents		0 - 10	%		4	%		4	%
Equity securities:
U.S. large capitalization		33 - 43			38			39
U.S. small and mid-capitalization		3 - 13			8			10
International		10 - 20			13			14
Total equity		55 - 65			59			63
Debt securities		30 - 40			37			33
Total					100	%		100	%

In general, the U.S. large capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, U.S. small capitalization, and U.S. mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-U.S. dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren's investment in private equity funds consists of 10 different limited partnerships, with invested capital ranging from $0.1 million to $7 million each, which invest primarily in a diversified number of small U.S.-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren's investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations, to increase or to reduce market exposure in an efficient and timely manner.

Fair Value Measurements of Plan Assets

Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2011. The fair value of an asset is the amount that would be received upon sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the last business day on or before the measurement date. Securities traded in over-the-counter markets are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	31	$	-	$	31
Equity securities:
U.S. large capitalization		72			922		-		994
U.S. small and mid-capitalization		202			11		-		213
International and emerging markets		115			213		-		328
Debt securities:
Corporate bonds		-			720		-		720
Municipal bonds		-			176		-		176
U.S. treasury and agency securities		-			230		-		230
Other		-			121		-		121
Real estate		-			-		108		108
Private equity		-			-		23		23
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	389		$	2,424	$	131	$	2,944
Less: Medical benefit assets at December 31(a)									(91	)
Plus: Net receivables at December 31(b)									23
Fair value of pension plans assets at year end								$	2,876

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	20	$	-	$	20
Equity securities:
U.S. large capitalization		70			812		-		882
U.S. small and mid-capitalization		299			10		-		309
International and emerging markets		129			284		-		413
Debt securities:
Corporate bonds		-			646		-		646
Municipal bonds		-			129		-		129
U.S. treasury and agency securities		-			154		-		154
Other		-			100		-		100
Real estate		-			-		98		98
Private equity		-			-		28		28
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	498		$	2,155	$	126	$	2,779
Less: Medical benefit assets at December 31(a)									(85	)
Plus: Net receivables at December 31(b)									28
Fair value of pension plans assets at year end								$	2,722

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2011, and 2010:

	Beginning Balance at January 1,		Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date			Actual Return on Plan Assets Related to Assets Sold During the Period		Purchases, Sales, and Settlements, net			Net Transfers into (out of) of Level 3		Ending Balance at December 31,
2011:
Real estate	$	98	$	10		$	-	$	-		$	-	$	108
Private equity		28		(10	)		11		(6	)		-		23
2010:
Other debt securities	$	1	$	-		$	-	$	(1	)	$	-	$	-
Real estate		90		7			-		1			-		98
Private equity		33		(5	)		7		(7	)		-		28

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1	$	66	$	-	$	67
Equity securities:
U.S. large capitalization		235		78		-		313
U.S. small and mid-capitalization		57		-		-		57
International		44		56		-		100
Debt securities:
Corporate bonds		-		61		-		61
Municipal bonds		-		86		-		86
U.S. treasury and agency securities		-		82		-		82
Asset-backed securities		-		23		-		23
Other		-		49		-		49
Total	$	337	$	501	$	-	$	838
Plus: Medical benefit assets at December 31(a)								91
Less: Net payables at December 31(b)								(33	)
Fair value of postretirement benefit plans assets at year end							$	896

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-	$	35	$	-	$	35
Equity securities:
U.S. large capitalization		215		72		-		287
U.S. small and mid-capitalization		66		-		-		66
International		43		51		-		94
Debt securities:
Corporate bonds		-		59		-		59
Municipal bonds		-		58		-		58
U.S. treasury and agency securities		-		59		-		59
Asset-backed securities		-		31		-		31
Other		-		29		-		29
Total	$	324	$	394	$	-	$	718
Plus: Medical benefit assets at December 31(a)								85
Less: Net payables at December 31(b)								(6	)
Fair value of postretirement benefit plans assets at year end							$	797

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2011, 2010, and 2009:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
2011:
Service cost	$	75		$	22
Interest cost		180			58
Expected return on plan assets		(216	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		(1	)		(8	)
Actuarial loss		42			5
Net periodic benefit cost	$	80		$	25
2010:
Service cost	$	68		$	20
Interest cost		185			62
Expected return on plan assets		(212	)		(56	)
Amortization of:
Transition obligation		-			2
Prior service cost		6			(8	)
Actuarial loss		18			1
Net periodic benefit cost	$	65		$	21
2009:
Service cost	$	68		$	19
Interest cost		186			66
Expected return on plan assets		(206	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		9			(8	)
Actuarial loss		24			9
Net periodic benefit cost	$	81		$	34

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

The current year expected return on plan assets is determined primarily by adjusting the prior-year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.

The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2012 are as follows:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
Regulatory assets:
Transition obligation	$	-		$	2
Prior service cost (credit)		(1	)		(4	)
Net actuarial loss		87			23
Accumulated OCI:
Transition obligation		-			-
Prior service cost (credit)		(1	)		(1	)
Net actuarial loss		6			3
Total	$	91		$	23

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

Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The net actuarial loss subject to amortization is amortized on a straight-line basis over 10 years.

Ameren Missouri, Ameren Illinois and Genco are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred for the years ended December 31, 2011, 2010, and 2009:

	Pension Costs						Postretirement Costs
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	80	$	65	$	81	$	25	$	21	$	34
Ameren Missouri		51		42		50		11		11		15
Ameren Illinois		16		10		14		11		7		16
Genco		8		9		11		3		2		3

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

The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2011, are as follows:

	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust		Paid from Company Funds		Paid from Qualified Trust		Paid from Company Funds		Federal Subsidy
2012		223		3		68		3		5
2013		225		3		71		3		5
2014		230		3		74		3		5
2015		231		3		77		3		6
2016		232		3		80		3		6
2017 - 2021		1,167		12		443		14		32

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2011, 2010, and 2009:

	Pension Benefits									Postretirement Benefits
	2011			2010			2009			2011			2010			2009
Discount rate at measurement date		5.25	%		5.75	%		5.75	%		5.25	%		5.75	%		5.75	%
Expected return on plan assets		8.00			8.00			8.00			7.75			8.00			8.00
Increase in future compensation		3.50			3.50			4.00			3.50			3.50			4.00
Medical cost trend rate (initial)		-			-			-			6.00			6.50			7.00
Medical cost trend rate (ultimate)		-			-			-			5.00			5.00			5.00
Years to ultimate rate		-			-			-			2 years			3 years			4 years

The table below reflects the sensitivity of Ameren's plans to potential changes in key assumptions:

	Pension Benefits					Postretirement Benefits
	Service Cost and Interest Cost			Projected Benefit Obligation		Service Cost and Interest Cost			Postretirement Benefit Obligation
0.25% decrease in discount rate	$	(2	)	$	110	$	-		$	38
0.25% increase in salary scale		2			14		-			-
1.00% increase in annual medical trend		-			-		3			42
1.00% decrease in annual medical trend		-			-		(3	)		(41	)

Other

Ameren sponsors a 401(k) plan for eligible employees. The Ameren plan covered all eligible employees of the Ameren Companies at December 31, 2011. The plans allowed employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matched a percentage of the employee contributions up to certain limits. The following table presents the portion of the 401(k) matching contribution to the Ameren plan attributable to each of the Ameren Companies for the years ended December 31, 2011, 2010, and 2009:

	2011		2010		2009
Ameren(a)	$	28	$	27	$	24
Ameren Missouri		16		16		14
Ameren Illinois		8		8		7
Genco		2		1		2

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

Ameren Energy Generating Company [Member]

Retirement Benefits

NOTE 11 – RETIREMENT BENEFITS

The primary objective of the Ameren pension plans and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offers defined benefit pension and postretirement benefit plans covering substantially all of its employees. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren Missouri, Ameren Illinois and Genco, excluding EEI, each participate in Ameren's single-employer pension and other postretirement plans. Ameren's qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded non-qualified pension plan, the Ameren Supplemental Retirement Plan, which is available for certain management employees and retirees to provide a supplemental benefit when their qualified pension plan benefits are reduced to comply with Internal Revenue Code limitations. Ameren's other postretirement plans are the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. Separately, EEI employees and retirees participate in EEI's single-employer pension and other postretirement plans. EEI's pension plan is the Revised Retirement Plan for Employees of Electric Energy, Inc. EEI's other postretirement plans are the Group Insurance Plan for Management Employees of Electric Energy, Inc. and the Group Insurance Plan for Bargaining Unit Employees of Electric Energy, Inc. Nonaffiliated Ameren companies do not participate in the Ameren Retirement Plan, the Ameren Supplemental Retirement Plan, the Ameren Retiree Medical Plan, and the Ameren Group Life Insurance Plan. Ameren and Genco each consolidate EEI, and therefore, EEI's plans are reflected in Ameren's and Genco's pension and postretirement balances and disclosures.

The following table presents the benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2011:

Ameren(a)	$	1,350
Ameren Missouri		494
Ameren Illinois		496
Genco		141

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

Ameren recognizes the underfunded status of its pension and postretirement plans as a liability on its balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance. The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2011, and 2010. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2011, and 2010, that have not been recognized in net periodic benefit costs.

	2011						2010
	Pension Benefits(a)			Postretirement Benefits(a)			Pension Benefits(a)			Postretirement Benefits(a)
Accumulated benefit obligation at end of year	$	3,645		$	(b	)	$	3,246		$	(b	)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	3,451		$	1,120		$	3,255		$	1,143
Service cost		75			22			68			20
Interest cost		180			58			185			62
Plan amendments(c)(d)		(16	)		-			(40	)		-
Participant contributions		-			18			-			17
Actuarial (gain) loss		348			96			165			(53	)
Benefits paid		(173	)		(66	)		(182	)		(74	)
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Net benefit obligation at end of year		3,865			1,257			3,451			1,120
Change in plan assets:
Fair value of plan assets at beginning of year		2,722			797			2,495			732
Actual return on plan assets		224			9			328			81
Employer contributions		103			129			81			36
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Participant contributions		-			18			-			17
Benefits paid		(173	)		(66	)		(182	)		(74	)
Fair value of plan assets at end of year		2,876			896			2,722			797
Funded status – deficiency		989			361			729			323
Accrued benefit cost at December 31	$	989		$	361		$	729		$	323
Amounts recognized in the balance sheet consist of:
Current liability	$	3		$	3		$	4		$	3
Noncurrent liability		986			358			725			320
Total	$	989		$	361		$	729		$	323
Amounts recognized in regulatory assets consist of:
Net actuarial loss	$	734		$	177		$	507		$	86
Prior service cost (credit)		(7	)		(28	)		(11	)		(32	)
Transition obligation		-			2			-			5
Amounts (pretax) recognized in accumulated OCI consist of:
Net actuarial loss		79			43			24			13
Prior service cost (credit)		(15	)		(7	)		4			(10	)
Total	$	791		$	187		$	524		$	62

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

(b) Not applicable.

(c) In 2011, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 430 labor union-represented employees from a traditional, final pay formula to a cash balance formula.

(d) In 2010, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 700 management employees from a traditional, final pay formula to a cash balance formula.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2011, and 2010:

	Pension Benefits						Postretirement Benefits
	2011			2010			2011			2010
Discount rate at measurement date		4.50	%		5.25	%		4.50	%		5.25	%
Increase in future compensation		3.50			3.50			3.50			3.50
Medical cost trend rate (initial)		-			-			5.50			6.00
Medical cost trend rate (ultimate)		-			-			5.00			5.00
Years to ultimate rate		-			-			10 year			2 years

Ameren determines discount rate assumptions by using an interest rate yield curve pursuant to authoritative accounting guidance on the determination of discount rates used for defined benefit plan obligations. The yield curve is based on the yields of more than 500 high-quality corporate bonds with maturities between zero and 30 years. A theoretical spot-rate curve constructed from this yield curve is then used as a guide to develop a discount rate matching the plans' payout structure.

Funding

Pension benefits are based on the employees' years of service and compensation. Ameren's pension plan is funded in compliance with income tax regulations and federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren's assumptions at December 31, 2011, its investment performance in 2011, and its pension funding policy, Ameren expects to make annual contributions of $90 million to $150 million in each of the next five years, with aggregate estimated contributions of $580 million. We expect Ameren Missouri's, Ameren Illinois' and Genco's portion of the future funding requirements to be 51%, 33%, and 12%, respectively. These amounts are estimates. The estimates may change based on actual investment performance, changes in interest rates, changes in our assumptions, any pertinent changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2011, 2010, and 2009:

	Pension Benefits						Postretirement Benefits
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	103	$	81	$	99	$	129	$	36	$	49
AMO		43		36		42		9		11		13
AIC		28		23		25		118		20		28
Genco		12		4		10		-		-		-

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

Investment Strategy and Policies

Ameren manages plan assets in accordance with the "prudent investor" guidelines contained in ERISA. The investment committee, to the extent authority is delegated to it by the finance committee of Ameren's board of directors, implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee's goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable, and second, to maximize total return on plan assets and minimize expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists in each asset class. As appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.

The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will utilize an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.75% and 7.50%, respectively, in 2012. No plan assets are expected to be returned to Ameren during 2012.

Ameren's investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value) and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee's strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 2012 and our pension and postretirement plans' asset categories as of December 31, 2011, and 2010.

				Percentage of Plan Assets at December  31,
Asset Category	Target Allocation 2012			2011			2010
Pension Plan:
Cash and cash equivalents		0  - 5	%		2	%		1	%
Equity securities:
U.S. large capitalization		29 - 39			33			31
U.S. small and mid-capitalization		2 - 12			7			11
International and emerging markets		9 - 19			11			15
Total equity		50 - 60			51			57
Debt securities		35 - 45			42			37
Real estate		0 - 9			4			4
Private equity		0 -4			1			1
Total					100	%		100	%
Postretirement Plans:
Cash and cash equivalents		0 - 10	%		4	%		4	%
Equity securities:
U.S. large capitalization		33 - 43			38			39
U.S. small and mid-capitalization		3 - 13			8			10
International		10 - 20			13			14
Total equity		55 - 65			59			63
Debt securities		30 - 40			37			33
Total					100	%		100	%

In general, the U.S. large capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, U.S. small capitalization, and U.S. mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-U.S. dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren's investment in private equity funds consists of 10 different limited partnerships, with invested capital ranging from $0.1 million to $7 million each, which invest primarily in a diversified number of small U.S.-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren's investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations, to increase or to reduce market exposure in an efficient and timely manner.

Fair Value Measurements of Plan Assets

Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2011. The fair value of an asset is the amount that would be received upon sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the last business day on or before the measurement date. Securities traded in over-the-counter markets are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	31	$	-	$	31
Equity securities:
U.S. large capitalization		72			922		-		994
U.S. small and mid-capitalization		202			11		-		213
International and emerging markets		115			213		-		328
Debt securities:
Corporate bonds		-			720		-		720
Municipal bonds		-			176		-		176
U.S. treasury and agency securities		-			230		-		230
Other		-			121		-		121
Real estate		-			-		108		108
Private equity		-			-		23		23
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	389		$	2,424	$	131	$	2,944
Less: Medical benefit assets at December 31(a)									(91	)
Plus: Net receivables at December 31(b)									23
Fair value of pension plans assets at year end								$	2,876

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	20	$	-	$	20
Equity securities:
U.S. large capitalization		70			812		-		882
U.S. small and mid-capitalization		299			10		-		309
International and emerging markets		129			284		-		413
Debt securities:
Corporate bonds		-			646		-		646
Municipal bonds		-			129		-		129
U.S. treasury and agency securities		-			154		-		154
Other		-			100		-		100
Real estate		-			-		98		98
Private equity		-			-		28		28
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	498		$	2,155	$	126	$	2,779
Less: Medical benefit assets at December 31(a)									(85	)
Plus: Net receivables at December 31(b)									28
Fair value of pension plans assets at year end								$	2,722

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2011, and 2010:

	Beginning Balance at January 1,		Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date			Actual Return on Plan Assets Related to Assets Sold During the Period		Purchases, Sales, and Settlements, net			Net Transfers into (out of) of Level 3		Ending Balance at December 31,
2011:
Real estate	$	98	$	10		$	-	$	-		$	-	$	108
Private equity		28		(10	)		11		(6	)		-		23
2010:
Other debt securities	$	1	$	-		$	-	$	(1	)	$	-	$	-
Real estate		90		7			-		1			-		98
Private equity		33		(5	)		7		(7	)		-		28

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1	$	66	$	-	$	67
Equity securities:
U.S. large capitalization		235		78		-		313
U.S. small and mid-capitalization		57		-		-		57
International		44		56		-		100
Debt securities:
Corporate bonds		-		61		-		61
Municipal bonds		-		86		-		86
U.S. treasury and agency securities		-		82		-		82
Asset-backed securities		-		23		-		23
Other		-		49		-		49
Total	$	337	$	501	$	-	$	838
Plus: Medical benefit assets at December 31(a)								91
Less: Net payables at December 31(b)								(33	)
Fair value of postretirement benefit plans assets at year end							$	896

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-	$	35	$	-	$	35
Equity securities:
U.S. large capitalization		215		72		-		287
U.S. small and mid-capitalization		66		-		-		66
International		43		51		-		94
Debt securities:
Corporate bonds		-		59		-		59
Municipal bonds		-		58		-		58
U.S. treasury and agency securities		-		59		-		59
Asset-backed securities		-		31		-		31
Other		-		29		-		29
Total	$	324	$	394	$	-	$	718
Plus: Medical benefit assets at December 31(a)								85
Less: Net payables at December 31(b)								(6	)
Fair value of postretirement benefit plans assets at year end							$	797

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2011, 2010, and 2009:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
2011:
Service cost	$	75		$	22
Interest cost		180			58
Expected return on plan assets		(216	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		(1	)		(8	)
Actuarial loss		42			5
Net periodic benefit cost	$	80		$	25
2010:
Service cost	$	68		$	20
Interest cost		185			62
Expected return on plan assets		(212	)		(56	)
Amortization of:
Transition obligation		-			2
Prior service cost		6			(8	)
Actuarial loss		18			1
Net periodic benefit cost	$	65		$	21
2009:
Service cost	$	68		$	19
Interest cost		186			66
Expected return on plan assets		(206	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		9			(8	)
Actuarial loss		24			9
Net periodic benefit cost	$	81		$	34

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

The current year expected return on plan assets is determined primarily by adjusting the prior-year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.

The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2012 are as follows:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
Regulatory assets:
Transition obligation	$	-		$	2
Prior service cost (credit)		(1	)		(4	)
Net actuarial loss		87			23
Accumulated OCI:
Transition obligation		-			-
Prior service cost (credit)		(1	)		(1	)
Net actuarial loss		6			3
Total	$	91		$	23

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

Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The net actuarial loss subject to amortization is amortized on a straight-line basis over 10 years.

Ameren Missouri, Ameren Illinois and Genco are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred for the years ended December 31, 2011, 2010, and 2009:

	Pension Costs						Postretirement Costs
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	80	$	65	$	81	$	25	$	21	$	34
Ameren Missouri		51		42		50		11		11		15
Ameren Illinois		16		10		14		11		7		16
Genco		8		9		11		3		2		3

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

The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2011, are as follows:

	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust		Paid from Company Funds		Paid from Qualified Trust		Paid from Company Funds		Federal Subsidy
2012		223		3		68		3		5
2013		225		3		71		3		5
2014		230		3		74		3		5
2015		231		3		77		3		6
2016		232		3		80		3		6
2017 - 2021		1,167		12		443		14		32

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2011, 2010, and 2009:

	Pension Benefits									Postretirement Benefits
	2011			2010			2009			2011			2010			2009
Discount rate at measurement date		5.25	%		5.75	%		5.75	%		5.25	%		5.75	%		5.75	%
Expected return on plan assets		8.00			8.00			8.00			7.75			8.00			8.00
Increase in future compensation		3.50			3.50			4.00			3.50			3.50			4.00
Medical cost trend rate (initial)		-			-			-			6.00			6.50			7.00
Medical cost trend rate (ultimate)		-			-			-			5.00			5.00			5.00
Years to ultimate rate		-			-			-			2 years			3 years			4 years

The table below reflects the sensitivity of Ameren's plans to potential changes in key assumptions:

	Pension Benefits					Postretirement Benefits
	Service Cost and Interest Cost			Projected Benefit Obligation		Service Cost and Interest Cost			Postretirement Benefit Obligation
0.25% decrease in discount rate	$	(2	)	$	110	$	-		$	38
0.25% increase in salary scale		2			14		-			-
1.00% increase in annual medical trend		-			-		3			42
1.00% decrease in annual medical trend		-			-		(3	)		(41	)

Other

Ameren sponsors a 401(k) plan for eligible employees. The Ameren plan covered all eligible employees of the Ameren Companies at December 31, 2011. The plans allowed employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matched a percentage of the employee contributions up to certain limits. The following table presents the portion of the 401(k) matching contribution to the Ameren plan attributable to each of the Ameren Companies for the years ended December 31, 2011, 2010, and 2009:

	2011		2010		2009
Ameren(a)	$	28	$	27	$	24
Ameren Missouri		16		16		14
Ameren Illinois		8		8		7
Genco		2		1		2

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

Union Electric Company [Member]

Retirement Benefits

NOTE 11 – RETIREMENT BENEFITS

The primary objective of the Ameren pension plans and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offers defined benefit pension and postretirement benefit plans covering substantially all of its employees. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren Missouri, Ameren Illinois and Genco, excluding EEI, each participate in Ameren's single-employer pension and other postretirement plans. Ameren's qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded non-qualified pension plan, the Ameren Supplemental Retirement Plan, which is available for certain management employees and retirees to provide a supplemental benefit when their qualified pension plan benefits are reduced to comply with Internal Revenue Code limitations. Ameren's other postretirement plans are the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. Separately, EEI employees and retirees participate in EEI's single-employer pension and other postretirement plans. EEI's pension plan is the Revised Retirement Plan for Employees of Electric Energy, Inc. EEI's other postretirement plans are the Group Insurance Plan for Management Employees of Electric Energy, Inc. and the Group Insurance Plan for Bargaining Unit Employees of Electric Energy, Inc. Nonaffiliated Ameren companies do not participate in the Ameren Retirement Plan, the Ameren Supplemental Retirement Plan, the Ameren Retiree Medical Plan, and the Ameren Group Life Insurance Plan. Ameren and Genco each consolidate EEI, and therefore, EEI's plans are reflected in Ameren's and Genco's pension and postretirement balances and disclosures.

The following table presents the benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2011:

Ameren(a)	$	1,350
Ameren Missouri		494
Ameren Illinois		496
Genco		141

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

Ameren recognizes the underfunded status of its pension and postretirement plans as a liability on its balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance. The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2011, and 2010. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2011, and 2010, that have not been recognized in net periodic benefit costs.

	2011						2010
	Pension Benefits(a)			Postretirement Benefits(a)			Pension Benefits(a)			Postretirement Benefits(a)
Accumulated benefit obligation at end of year	$	3,645		$	(b	)	$	3,246		$	(b	)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	3,451		$	1,120		$	3,255		$	1,143
Service cost		75			22			68			20
Interest cost		180			58			185			62
Plan amendments(c)(d)		(16	)		-			(40	)		-
Participant contributions		-			18			-			17
Actuarial (gain) loss		348			96			165			(53	)
Benefits paid		(173	)		(66	)		(182	)		(74	)
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Net benefit obligation at end of year		3,865			1,257			3,451			1,120
Change in plan assets:
Fair value of plan assets at beginning of year		2,722			797			2,495			732
Actual return on plan assets		224			9			328			81
Employer contributions		103			129			81			36
Federal subsidy on benefits paid		(b	)		6			(b	)		5
Early retiree reinsurance program receipt		(b	)		3			(b	)		-
Participant contributions		-			18			-			17
Benefits paid		(173	)		(66	)		(182	)		(74	)
Fair value of plan assets at end of year		2,876			896			2,722			797
Funded status – deficiency		989			361			729			323
Accrued benefit cost at December 31	$	989		$	361		$	729		$	323
Amounts recognized in the balance sheet consist of:
Current liability	$	3		$	3		$	4		$	3
Noncurrent liability		986			358			725			320
Total	$	989		$	361		$	729		$	323
Amounts recognized in regulatory assets consist of:
Net actuarial loss	$	734		$	177		$	507		$	86
Prior service cost (credit)		(7	)		(28	)		(11	)		(32	)
Transition obligation		-			2			-			5
Amounts (pretax) recognized in accumulated OCI consist of:
Net actuarial loss		79			43			24			13
Prior service cost (credit)		(15	)		(7	)		4			(10	)
Total	$	791		$	187		$	524		$	62

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

(b) Not applicable.

(c) In 2011, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 430 labor union-represented employees from a traditional, final pay formula to a cash balance formula.

(d) In 2010, Ameren's pension plan was amended to adjust the calculation of the future benefit obligation of approximately 700 management employees from a traditional, final pay formula to a cash balance formula.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2011, and 2010:

	Pension Benefits						Postretirement Benefits
	2011			2010			2011			2010
Discount rate at measurement date		4.50	%		5.25	%		4.50	%		5.25	%
Increase in future compensation		3.50			3.50			3.50			3.50
Medical cost trend rate (initial)		-			-			5.50			6.00
Medical cost trend rate (ultimate)		-			-			5.00			5.00
Years to ultimate rate		-			-			10 year			2 years

Ameren determines discount rate assumptions by using an interest rate yield curve pursuant to authoritative accounting guidance on the determination of discount rates used for defined benefit plan obligations. The yield curve is based on the yields of more than 500 high-quality corporate bonds with maturities between zero and 30 years. A theoretical spot-rate curve constructed from this yield curve is then used as a guide to develop a discount rate matching the plans' payout structure.

Funding

Pension benefits are based on the employees' years of service and compensation. Ameren's pension plan is funded in compliance with income tax regulations and federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren's assumptions at December 31, 2011, its investment performance in 2011, and its pension funding policy, Ameren expects to make annual contributions of $90 million to $150 million in each of the next five years, with aggregate estimated contributions of $580 million. We expect Ameren Missouri's, Ameren Illinois' and Genco's portion of the future funding requirements to be 51%, 33%, and 12%, respectively. These amounts are estimates. The estimates may change based on actual investment performance, changes in interest rates, changes in our assumptions, any pertinent changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2011, 2010, and 2009:

	Pension Benefits						Postretirement Benefits
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	103	$	81	$	99	$	129	$	36	$	49
AMO		43		36		42		9		11		13
AIC		28		23		25		118		20		28
Genco		12		4		10		-		-		-

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

Investment Strategy and Policies

Ameren manages plan assets in accordance with the "prudent investor" guidelines contained in ERISA. The investment committee, to the extent authority is delegated to it by the finance committee of Ameren's board of directors, implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee's goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable, and second, to maximize total return on plan assets and minimize expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists in each asset class. As appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.

The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will utilize an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.75% and 7.50%, respectively, in 2012. No plan assets are expected to be returned to Ameren during 2012.

Ameren's investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value) and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee's strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 2012 and our pension and postretirement plans' asset categories as of December 31, 2011, and 2010.

				Percentage of Plan Assets at December  31,
Asset Category	Target Allocation 2012			2011			2010
Pension Plan:
Cash and cash equivalents		0  - 5	%		2	%		1	%
Equity securities:
U.S. large capitalization		29 - 39			33			31
U.S. small and mid-capitalization		2 - 12			7			11
International and emerging markets		9 - 19			11			15
Total equity		50 - 60			51			57
Debt securities		35 - 45			42			37
Real estate		0 - 9			4			4
Private equity		0 -4			1			1
Total					100	%		100	%
Postretirement Plans:
Cash and cash equivalents		0 - 10	%		4	%		4	%
Equity securities:
U.S. large capitalization		33 - 43			38			39
U.S. small and mid-capitalization		3 - 13			8			10
International		10 - 20			13			14
Total equity		55 - 65			59			63
Debt securities		30 - 40			37			33
Total					100	%		100	%

In general, the U.S. large capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, U.S. small capitalization, and U.S. mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-U.S. dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren's investment in private equity funds consists of 10 different limited partnerships, with invested capital ranging from $0.1 million to $7 million each, which invest primarily in a diversified number of small U.S.-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren's investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations, to increase or to reduce market exposure in an efficient and timely manner.

Fair Value Measurements of Plan Assets

Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2011. The fair value of an asset is the amount that would be received upon sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the last business day on or before the measurement date. Securities traded in over-the-counter markets are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	31	$	-	$	31
Equity securities:
U.S. large capitalization		72			922		-		994
U.S. small and mid-capitalization		202			11		-		213
International and emerging markets		115			213		-		328
Debt securities:
Corporate bonds		-			720		-		720
Municipal bonds		-			176		-		176
U.S. treasury and agency securities		-			230		-		230
Other		-			121		-		121
Real estate		-			-		108		108
Private equity		-			-		23		23
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	389		$	2,424	$	131	$	2,944
Less: Medical benefit assets at December 31(a)									(91	)
Plus: Net receivables at December 31(b)									23
Fair value of pension plans assets at year end								$	2,876

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-		$	20	$	-	$	20
Equity securities:
U.S. large capitalization		70			812		-		882
U.S. small and mid-capitalization		299			10		-		309
International and emerging markets		129			284		-		413
Debt securities:
Corporate bonds		-			646		-		646
Municipal bonds		-			129		-		129
U.S. treasury and agency securities		-			154		-		154
Other		-			100		-		100
Real estate		-			-		98		98
Private equity		-			-		28		28
Derivative assets		1			-		-		1
Derivative liabilities		(1	)		-		-		(1	)
Total	$	498		$	2,155	$	126	$	2,779
Less: Medical benefit assets at December 31(a)									(85	)
Plus: Net receivables at December 31(b)									28
Fair value of pension plans assets at year end								$	2,722

(a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.

(b) Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2011, and 2010:

	Beginning Balance at January 1,		Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date			Actual Return on Plan Assets Related to Assets Sold During the Period		Purchases, Sales, and Settlements, net			Net Transfers into (out of) of Level 3		Ending Balance at December 31,
2011:
Real estate	$	98	$	10		$	-	$	-		$	-	$	108
Private equity		28		(10	)		11		(6	)		-		23
2010:
Other debt securities	$	1	$	-		$	-	$	(1	)	$	-	$	-
Real estate		90		7			-		1			-		98
Private equity		33		(5	)		7		(7	)		-		28

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2011:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1	$	66	$	-	$	67
Equity securities:
U.S. large capitalization		235		78		-		313
U.S. small and mid-capitalization		57		-		-		57
International		44		56		-		100
Debt securities:
Corporate bonds		-		61		-		61
Municipal bonds		-		86		-		86
U.S. treasury and agency securities		-		82		-		82
Asset-backed securities		-		23		-		23
Other		-		49		-		49
Total	$	337	$	501	$	-	$	838
Plus: Medical benefit assets at December 31(a)								91
Less: Net payables at December 31(b)								(33	)
Fair value of postretirement benefit plans assets at year end							$	896

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2010:

	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	-	$	35	$	-	$	35
Equity securities:
U.S. large capitalization		215		72		-		287
U.S. small and mid-capitalization		66		-		-		66
International		43		51		-		94
Debt securities:
Corporate bonds		-		59		-		59
Municipal bonds		-		58		-		58
U.S. treasury and agency securities		-		59		-		59
Asset-backed securities		-		31		-		31
Other		-		29		-		29
Total	$	324	$	394	$	-	$	718
Plus: Medical benefit assets at December 31(a)								85
Less: Net payables at December 31(b)								(6	)
Fair value of postretirement benefit plans assets at year end							$	797

(a) Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b) Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.

Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2011, 2010, and 2009:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
2011:
Service cost	$	75		$	22
Interest cost		180			58
Expected return on plan assets		(216	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		(1	)		(8	)
Actuarial loss		42			5
Net periodic benefit cost	$	80		$	25
2010:
Service cost	$	68		$	20
Interest cost		185			62
Expected return on plan assets		(212	)		(56	)
Amortization of:
Transition obligation		-			2
Prior service cost		6			(8	)
Actuarial loss		18			1
Net periodic benefit cost	$	65		$	21
2009:
Service cost	$	68		$	19
Interest cost		186			66
Expected return on plan assets		(206	)		(54	)
Amortization of:
Transition obligation		-			2
Prior service cost		9			(8	)
Actuarial loss		24			9
Net periodic benefit cost	$	81		$	34

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

The current year expected return on plan assets is determined primarily by adjusting the prior-year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.

The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2012 are as follows:

	Pension Benefits			Postretirement Benefits
	Ameren(a)			Ameren(a)
Regulatory assets:
Transition obligation	$	-		$	2
Prior service cost (credit)		(1	)		(4	)
Net actuarial loss		87			23
Accumulated OCI:
Transition obligation		-			-
Prior service cost (credit)		(1	)		(1	)
Net actuarial loss		6			3
Total	$	91		$	23

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

Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The net actuarial loss subject to amortization is amortized on a straight-line basis over 10 years.

Ameren Missouri, Ameren Illinois and Genco are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred for the years ended December 31, 2011, 2010, and 2009:

	Pension Costs						Postretirement Costs
	2011		2010		2009		2011		2010		2009
Ameren(a)	$	80	$	65	$	81	$	25	$	21	$	34
Ameren Missouri		51		42		50		11		11		15
Ameren Illinois		16		10		14		11		7		16
Genco		8		9		11		3		2		3

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

The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2011, are as follows:

	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust		Paid from Company Funds		Paid from Qualified Trust		Paid from Company Funds		Federal Subsidy
2012		223		3		68		3		5
2013		225		3		71		3		5
2014		230		3		74		3		5
2015		231		3		77		3		6
2016		232		3		80		3		6
2017 - 2021		1,167		12		443		14		32

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2011, 2010, and 2009:

	Pension Benefits									Postretirement Benefits
	2011			2010			2009			2011			2010			2009
Discount rate at measurement date		5.25	%		5.75	%		5.75	%		5.25	%		5.75	%		5.75	%
Expected return on plan assets		8.00			8.00			8.00			7.75			8.00			8.00
Increase in future compensation		3.50			3.50			4.00			3.50			3.50			4.00
Medical cost trend rate (initial)		-			-			-			6.00			6.50			7.00
Medical cost trend rate (ultimate)		-			-			-			5.00			5.00			5.00
Years to ultimate rate		-			-			-			2 years			3 years			4 years

The table below reflects the sensitivity of Ameren's plans to potential changes in key assumptions:

	Pension Benefits					Postretirement Benefits
	Service Cost and Interest Cost			Projected Benefit Obligation		Service Cost and Interest Cost			Postretirement Benefit Obligation
0.25% decrease in discount rate	$	(2	)	$	110	$	-		$	38
0.25% increase in salary scale		2			14		-			-
1.00% increase in annual medical trend		-			-		3			42
1.00% decrease in annual medical trend		-			-		(3	)		(41	)

Other

Ameren sponsors a 401(k) plan for eligible employees. The Ameren plan covered all eligible employees of the Ameren Companies at December 31, 2011. The plans allowed employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matched a percentage of the employee contributions up to certain limits. The following table presents the portion of the 401(k) matching contribution to the Ameren plan attributable to each of the Ameren Companies for the years ended December 31, 2011, 2010, and 2009:

	2011		2010		2009
Ameren(a)	$	28	$	27	$	24
Ameren Missouri		16		16		14
Ameren Illinois		8		8		7
Genco		2		1		2

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