2016 Annual Attachment O Stakeholder Meeting Ameren Missouri July 6, 2016

Agenda Primary purpose is to review AMMO Pricing Zone Historical 2015 Transmission Rate Calculations which became effective June 1, 2016 Protocol Timeline Comparison to Previous Revenue Requirement 2015 AMMO Pricing Zone NITS Charge ROE Complaint

Protocol timeline Date Action (Historical) June 1 Posting of annual update Information exchange period begins. Review period begins. September 1 Deadline for annual meeting November 1 Deadline for joint meeting on regional cost-shared projects December 1 Deadline for Interested Parties to submit information requests January 10 Deadline for Transmission Owners to respond to information requests January 31 Deadline for Interested Parties to submit Informal Challenges February 28 Deadline for Transmission Owners to respond to Informal Challenges Any rate changes agreed to by the Transmission Owner will be included in the Information Filing and will be reflected in the Annual Update for the following Rate Year. March 15 Transmission Owners submit informational filing to the Commission. March 31 Deadline for Interested Parties to file Formal Challenge at the Commission

June 2015 vs June 2016 Calculation Ameren Missouri Revenue Requirement June 2015 vs June 2016 Calculation

Ameren Missouri June 2016 Calculation Rate Base Page.Line Jun-15 Jun-16 Change Percent 2.6 Total Gross Plant 973,505,027 1,002,549,260 29,044,233 3% 2.12 Total Accum Depreciation 297,149,632 317,488,807 20,339,175 7% 2.18 TOTAL NET PLANT 676,355,395 685,060,453 8,705,058 1% ADJUSTMENTS TO RATE BASE 2.20 Account No. 282 (186,057,383) (193,381,672) (7,324,289) 4% 2.21 Account No. 283 (10,290,367) (6,947,952) 3,342,415 -32% 2.22 Account No. 190 8,195,106 4,830,788 (3,364,318) -41% 2.25 Land Held for Future Use 3,334,568 0% 2.26 CWC 3,795,767 4,099,708 303,941 8% 2.27 Materials & Supplies 4,625,788 7,423,375 2,797,587 60% 2.28 Prepayments 1,197,264 946,165 (251,099) -21% TOTAL ADJUSTMENTS (175,199,257) (179,695,021) (4,495,764) 2.30 TOTAL RATE BASE 501,156,138 505,365,432 4,209,294

Ameren Missouri June 2016 Calculation Expenses Page.Line Jun-15 Jun-16 Change Percent O&M 3.1 Transmission 57,433,561 67,034,333 9,600,772 17% 3.1a Less LSE Expenses 6,344,330 6,469,633 125,303 2% 3.2 Less Account 565 28,061,521 36,318,361 8,256,840 29% 3.3 A&G 6,903,236 8,060,504 1,157,268 3.4 Less FERC Annual Fees - N/A 3.5 Less EPRI, ect. 543,536 651,660 108,124 20% 3.5a Plus Trans. Reg. Comm. Exp 170,481 41,882 (128,599) -75% 3.7 Transmission Lease Payments 808,248 1,100,598 292,350 36% 3.8 TOTAL O&M 30,366,139 32,797,662 2,431,523 8% 3.12 TOTAL DEPRECIATION 20,805,412 24,671,586 3,866,174 19% TAXES 3.13 Payroll 524,054 596,060 72,006 14% 3.16 Property 8,806,314 9,375,098 568,784 6% 3.18 Other 69,111 77,189 8,078 12% 3.27 Income Taxes 19,292,707 19,176,120 (116,587) -1% TOTAL TAXES 28,692,186 29,224,468 532,282 TOTAL EXPENSES 79,863,737 86,693,715 6,829,978 9%

Ameren Missouri June 2016 Calculation Capital Structure Capital Structure - June 2015 Page.Line $ % Cost Weighted 4.27 Long Term Debt 3,711,276,000 48% 0.0538 0.0257 4.28 Preferred Stock 80,759,500 1% 0.0424 0.0004 4.29 Common Stock 3,971,807,203 51% 0.1238 0.0633 4.3 Total 7,763,842,703 100% 0.0895 Capital Structure - June 2016 3,847,276,000 49% 0.0527 0.0256 4,001,834,831 50% 0.0625 7,929,870,331 0.0885 Change in Return -0.1008%

Ameren Missouri June 2016 Calculation Revenue Requirement Page.Line Jun-15 Jun-16 Change Percent 2.30 TOTAL RATE BASE 501,156,138 505,365,432 4,209,294 1% 4.30 Rate of Return 0.0895 0.0885 (0.0010) -1% 3.28 Return 44,852,283 44,719,548 (132,735) 0% Total Expenses 79,863,737 86,693,715 6,829,978 9% 3.29 TOTAL GROSS REV. REQ. 124,716,019 131,413,263 6,697,244 5% 3.30 Less ATT. GG Adjustment 8,089,316 8,088,230 (1,086) 3.30a Less ATT. MM Adjustment - N/A 3.31 GROSS REV. REQ. UNDER ATT. O 116,626,703 123,325,033 6,698,330 6%

Ameren Missouri June 2016 Calculation Net Revenue Requirement Page.Line Jun-15 Jun-16 Change Percent 1.1 Gross Revenue Requirement 116,626,703 123,325,033 6,698,330 6% 1.6 Total Revenue Credits 7,031,833 6,830,307 -201,526 -3% 1.6c Total Prior Period Adjustment (with interest) -976,420 -1,571 974,850 -100% 1.7 NET REVENUE REQUIREMENT 108,618,450 116,493,155 7,874,706 7% The Prior Period Adjustments relate to the FERC Audit Refund in Docket No. FA13-2-000

Ameren Missouri June 2016 Calculation AMMO Schedule 9 Rate Calculation Page.Line Jun-15 Jun-16 Change Percent 1.7 Net Revenue Requirement 108,618,450 116,493,155 7,874,706 7% 1.15 Ameren Missouri Divisor 6,949,405 6,518,000 (431,405) -6% Annual Cost ($/kW/Yr) 15.630 17.873 2.243 14% Network & P-to-P Rate ($/kW/Mo) 1.302 1.489 0.187 The divisor excludes the Southeast Missouri load included in the Entergy Arkansas, Inc. (EAI) pricing zone.

Ameren Missouri June 2016 Calculation Attachment GG Calculation - Page 1 (1) (2) (3) (4) Attachment O Line Page, Line, Col. Transmission Allocator No. 1 Gross Transmission Plant - Total Attach O, p 2, line 2 col 5 (Note A) 979,529,280 2 Net Transmission Plant - Total Attach O, p 2, line 14 and 23b col 5 (Note B) 670,399,913 O&M EXPENSE 3 Total O&M Allocated to Transmission Attach O, p 3, line 8 col 5 32,797,662 4 Annual Allocation Factor for O&M (line 3 divided by line 1 col 3) 3.35% GENERAL AND COMMON (G&C) DEPRECIATION EXPENSE 5 Total G&C Depreciation Expense Attach O, p 3, lines 10 & 11, col 5 (Note H) 1,117,252 6 Annual Allocation Factor for G&C Depreciation Expense (line 5 divided by line 1 col 3) 0.11% TAXES OTHER THAN INCOME TAXES 7 Total Other Taxes Attach O, p 3, line 20 col 5 10,048,348 8 Annual Allocation Factor for Other Taxes (line 7 divided by line 1 col 3) 1.03% 9 Annual Allocation Factor for Expense Sum of line 4, 6, and 8 4.49% INCOME TAXES 10 Total Income Taxes Attach O, p 3, line 27 col 5 19,176,120 11 Annual Allocation Factor for Income Taxes (line 10 divided by line 2 col 3) 2.86% RETURN 12 Return on Rate Base Attach O, p 3, line 28 col 5 44,719,548 13 Annual Allocation Factor for Return on Rate Base (line 12 divided by line 2 col 3) 6.67% 14 Annual Allocation Factor for Return Sum of line 11 and 13 9.53%

Ameren Missouri June 2016 Calculation Attachment GG Calculation - Page 2 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) Line No.   Project Name MTEP Project Number Project Gross Plant Annual Allocation Factor for Expense Annual Expense Charge Project Net Plant Annual Allocation Factor for Return Annual Return Charge Project Depreciation Expense Annual Revenue Requirement True-Up Adjustment Network Upgrade Charge (Note C) (Page 1 line 9) (Col. 3 * Col. 4) (Note D) (Page 1 line 14) (Col. 6 * Col. 7) (Note E) (Sum Col. 5, 8 & 9) (Note F) Sum Col. 10 & 11 (Note G) 1a Big River-Rockwood 138 kV 152 $ 15,611,046 4.49% $700,655.43 $ 14,695,121 9.53% $1,400,589 $239,591 $2,340,835 $ - 2,340,835 1b Reconductor Sioux-Huster-1 and -3 138 kV 1240 $ 15,620,832 $701,094.65 $ 14,235,260 $1,356,760 $445,464 $2,503,318 2,503,318 1c Gray Summit : 2nd 345/138 kV Transformer 2061 $ 22,410,810 $1,005,842.62 $ 20,355,716 $1,940,099 $298,135 $3,244,077 3,244,077 1d Lutesville: Northwest Cape 345/161 kV substation and new lines 2306 $ - $0.00 $ - $0 2 Annual Totals $8,088,230 3 Rev. Req. Adj For Attachment O

Significant transmission projects in 2015 and 2016 Completed in 2015 Project Name Total Cost Bland $15.4 Million To Be Completed in 2016 Project Name Total Cost Lutesville: Northwest Cape 345/161 kV substation and new lines $60 Million Viaduct-Cape Clark $24 Million Clark-Osage $43 Million

Roe complaint Current ROE is 12.38% MISO ROE Complaints 1st Complaint (EL14-12) Covers November 12, 2013 through Feb 11, 2015 Received initial decision from administrative law judge on December 22, 2015 with a recommended Base ROE at 10.32% Expect final FERC order in October 2016 2nd Complaint (EL15-45) Covers February 12, 2015 through May 11, 2016 Received initial decision on June 30, 2016 with a recommended Base ROE at 9.70% Expect final FERC order in first half of 2017 3rd Complaint has not been filed

MISO ROE Complaints (con’t) FERC approved a 50 basis point adder for participation in an RTO Effective January 6, 2015, but will not be used until after final orders in the ROE complaints are issued Refunds will be required, but format is not yet determined Could be either rolled into the next revenue requirement and reduce future rates or could be actual refunds to all customers Will impact Sch 7,8, 9, 26, 37, 38, 26A May require MISO to calculate adjustments for all months beginning with November 13

Transmission Pricing - Attachments O, GG & MM Information Miso web links Transmission Pricing - Attachments O, GG & MM Information https://www.misoenergy.org/MarketsOperations/TransmissionSettlements/Pages/TransmissionPricing.aspx Ameren OASIS http://www.oasis.oati.com/AMRN/index.html MTEP 15 https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/Pages/MTEP15.aspx MTEP 16 https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/Pages/MTEP16.aspx Schedule 26 & 26-A Indicative Charges https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/Pages/MTEPStudies.aspx

QUESTIONS?

Supplemental Background Information Appendix Supplemental Background Information

Ameren Missouri transmission Ameren Missouri is a transmission-owning subsidiary of Ameren Corporation, as well as a MISO Transmission Owner (TO) Ameren Illinois and Ameren Transmission Company of Illinois (ATXI) are two other Ameren subsidiaries that are MISO TOs. ATXI was formed to build and own new regional transmission projects such as the MISO Multi-Value Projects Ameren Missouri will continue to build and own traditional reliability projects needed to meet local needs and continue to maintain its existing transmission system Ameren Missouri recently completed a new local reliability project in Southeast Missouri. Ameren Missouri is the only MISO Transmission Owner in the AMMO pricing zone.

Calculate rates for Schedules 9, 26 & 26-A MISO ATTACHMENTs O & GG Calculate rates for Schedules 9, 26 & 26-A Attachment GG - Schedule 26 Attachment MM – Schedule 26-A Attachment O - net revenue requirement billed under Schedule 9 Schedules 26 and 26-A are billed by MISO Schedule 9 is billed by Ameren

Cost Recovery for certain Network Upgrades Eligible projects MISO ATTACHMENT gg Cost Recovery for certain Network Upgrades Eligible projects Market Efficiency Generator Interconnections Cost shared based upon project type MISO-wide based on load Subregional based on LODF (Line Outage Distribution Factor) Ameren Missouri has three Attachment GG projects completed and in rates. Project placed in-service in May not included in rates until next June. These projects were approved by MISO under prior Tariff provisions which allowed limited cost sharing for certain reliability projects Attachment MM is very similar to Attachment GG Applies to MISO Multi-Value Projects, but is not applicable to Ameren Missouri since it is not building or developing any MVPs.

All transmission costs included in Attachment O calculation MISO ATTACHMENT O & GG All transmission costs included in Attachment O calculation Schedule 9 based on net revenue requirement – reductions for: Any costs recovered in Schedules 26 & 26-A Revenue Credits Point-to-Point revenue in Schedules 7 & 8 Rental revenue Revenue from generator interconnections

Miso transmission expansion plan (MTEP) Developed on an annual basis building upon previous analysis MISO, Transmission Owners & Stakeholders Includes subregional planning meetings MTEP goals Ensure the reliability of the transmission system Ensure compliance with NERC Standards Provide economic benefits, such as increased market efficiency Facilitate public policy objectives, such as meeting Renewable Portfolio Standards Address other issues or goals identified through the stakeholder process Multiple future scenarios analyzed End result – comprehensive, cohesive plan for MISO footprint MTEP approved by MISO Board of Directors

Rate base items based on Dec 31 ending balances AMMO rate Inputs Rates calculated using prior year FERC Form 1 data (historical calculation) Rate base items based on Dec 31 ending balances Only wholesale customers pay the Schedule 9 Rate in AMMO About 7% of load Ameren Missouri retail customers Do not pay AMMO Schedule 9 Rate Ameren Missouri transmission facilities & costs included in bundled rates set by MoPSC Other transmission related costs also included in retail rate case Note that some Transmission Owners’ rate calculations are different Rates are initially set based on projected data Annual True-up calculation to reflect actual costs reported in Form 1