1. 2015 Annual Attachment O Stakeholder Meeting Ameren Missouri July 15, 2015

2. 2 AGENDA Primary purpose is to review AMMO Pricing Zone Historical 2014 Transmission Rate Calculations which became effective June 1, 2015 Protocol Timeline Comparison to Previous Revenue Requirement 2014 AMMO Pricing Zone NITS Charge

3. 3 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

4. 4 Ameren Missouri Revenue Requirement June 2014 vs June 2015 Calculation

5. 5 AMEREN MISSOURI JUNE 2015 CALCULATION Rate Base Page.Line Jun-14Jun-15ChangePercent 2.6Total Gross Plant843,566,308973,505,027129,938,71915% 2.12Total Accum Depreciation282,535,080297,149,63214,614,5525% 2.18TOTAL NET PLANT561,031,228676,355,395115,324,16621% ADJUSTMENTS TO RATE BASE 2.20 Account No. 282-151,726,236-186,057,383-34,331,14723% 2.21 Account No. 283-6,995,936-10,290,367-3,294,43247% 2.22 Account No. 1905,296,9178,195,1062,898,18955% 2.25 Land Held for Future Use799,4803,334,5682,535,088317% 2.26 CWC3,090,4333,795,767705,33423% 2.27 Materials & Supplies6,883,0994,625,788-2,257,311-33% 2.28 Prepayments901,2871,197,264295,97733% TOTAL ADJUSTMENTS-141,750,957-175,199,258-33,448,30124% 2.30TOTAL RATE BASE419,280,272501,156,13781,875,86520%

6. 6 AMEREN MISSOURI JUNE 2015 CALCULATION Expenses Page.Line Jun-14Jun-15ChangePercent O&M 3.1 Transmission56,001,55757,433,5611,432,0043% 3.1a Less LSE Expenses6,469,2296,344,330-124,899-2% 3.2 Less Account 56530,809,16028,061,521-2,747,639-9% 3.3 A&G5,704,0626,903,2361,199,17521% 3.4 Less FERC Annual Fees000N/A 3.5 Less EPRI, ect.445,447543,53698,08922% 3.5a Plus Trans. Reg. Comm. Exp67,179170,481103,302154% 3.7Transmission Lease Payments674,502808,248133,74620% 3.8TOTAL O&M24,723,46430,366,1395,642,67523% 3.12TOTAL DEPRECIATION18,065,64220,805,4122,739,77015% TAXES 3.13 Payroll477,114524,05446,94010% 3.16 Property7,898,1178,806,314908,19711% 3.18 Other87,18669,111-18,076-21% 3.27 Income Taxes16,529,79819,292,7072,762,90917% TOTAL TAXES24,992,21528,692,1863,699,97115% TOTAL EXPENSES67,781,32279,863,73712,082,41518%

7. 7 AMEREN MISSOURI JUNE 2015 CALCULATION Capital Structure Capital Structure - 2014 Page.Line $%CostWeighted 4.27 Long Term Debt3,465,276,00046%0.05880.0273 4.28 Preferred Stock80,759,5001%0.04240.0005 4.29 Common Stock3,912,960,92752%0.12380.0649 4.3Total7,458,996,427100%0.0927 Capital Structure - 2015 Page.Line $%CostWeighted 4.27 Long Term Debt3,711,276,00048%0.05380.0257 4.28 Preferred Stock80,759,5001%0.04240.0004 4.29 Common Stock3,971,807,20351%0.12380.0633 4.3Total7,763,842,703100%0.0895 Change in Return-0.3221%

8. 8 AMEREN MISSOURI JUNE 2015 CALCULATION Revenue Requirement Page.Line Jun-14Jun-15ChangePercent 2.30TOTAL RATE BASE419,280,272501,156,13781,875,86520% 4.30Rate of Return on ACS9.27%8.95%-0.32%-3% 3.28Return from ACS38,875,22044,852,2835,977,06215% Total Expenses67,781,32279,863,73712,082,41518% 3.29TOTAL GROSS REV. REQ.106,656,542124,716,01918,059,47717% 3.30Less ATT. GG Adjustment8,879,8478,089,316-790,531-9% 3.30aLess ATT. MM Adjustment000N/A 3.31GROSS REV. REQ. UNDER ATT. O97,776,695116,626,70318,850,00819%

9. 9 AMEREN MISSOURI JUNE 2015 CALCULATION Net Revenue Requirement The Prior Period Adjustment relates to the FERC Audit Refund in Docket No. FA13-2-000 Page.Line Jun-14Jun-15ChangePercent 1.1Gross Revenue Requirement97,776,695116,626,70318,850,00819% 1.6Total Revenue Credits9,091,0897,031,833-2,059,256-23% 1.6cTotal Prior Period Adjustment (with interest)-976,420 N/A 1.7NET REVENUE REQUIREMENT88,685,606108,618,45019,932,84322%

10. 10 AMEREN MISSOURI JUNE 2015 CALCULATION AMMO Schedule 9 Rate Calculation Page.Line Jun-14Jun-15ChangePercent 1.7Net Revenue Requirement88,685,606108,618,45019,932,84322% 1.15Ameren Missouri Divisor6,900,3076,996,82296,5151% Annual Cost ($/kW/Yr)12.85215.5242.67221% Network & P-to-P Rate ($/kW/Mo)1.0711.2940.22321%

11. 11 AMEREN MISSOURI JUNE 2015 CALCULATION Attachment GG Calculation - Page 1 (1)(2)(3)(4) Attachment O LinePage, Line, Col.TransmissionAllocator No. 1Gross Transmission Plant - TotalAttach O, p 2, line 2 col 5 (Note A)954,634,166 2Net Transmission Plant - TotalAttach O, p 2, line 14 and 23b col 5 (Note B) 665,462,357 O&M EXPENSE 3Total O&M Allocated to TransmissionAttach O, p 3, line 8 col 530,366,139 4Annual Allocation Factor for O&M(line 3 divided by line 1 col 3)3.18% GENERAL AND COMMON (G&C) DEPRECIATION EXPENSE 5Total G&C Depreciation ExpenseAttach O, p 3, lines 10 & 11, col 5 (Note H)839,936 6Annual Allocation Factor for G&C Depreciation Expense(line 5 divided by line 1 col 3)0.09% TAXES OTHER THAN INCOME TAXES 7Total Other TaxesAttach O, p 3, line 20 col 59,399,479 8Annual Allocation Factor for Other Taxes(line 7 divided by line 1 col 3)0.98% 9Annual Allocation Factor for ExpenseSum of line 4, 6, and 84.25% INCOME TAXES 10Total Income TaxesAttach O, p 3, line 27 col 519,292,707 11Annual Allocation Factor for Income Taxes(line 10 divided by line 2 col 3)2.90% RETURN 12Return on Rate BaseAttach O, p 3, line 28 col 544,852,283 13Annual Allocation Factor for Return on Rate Base(line 12 divided by line 2 col 3)6.74% 14Annual Allocation Factor for ReturnSum of line 11 and 139.64%

12. 12 AMEREN MISSOURI JUNE 2015 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) 1aBig River-Rockwood 138 kV152 $ 15,537,8934.25%$660,907.37 $ 14,866,2789.64%$1,432,984.54$237,192$2,331,083.79 $ -2,331,084 1bReconductor Sioux-Huster-1 and -3 138 kV1240 $ 15,620,8324.25%$664,435.20 $ 14,680,7249.64%$1,415,098.67$336,452$2,415,986.33 $ -2,415,986 1cGray Summit : 2nd 345/138 kV Transformer2061 $ 22,410,8104.25%$953,248.26 $ 20,653,8549.64%$1,990,858.25$398,139$3,342,245.79 $ -3,342,246 1dLutesville: Northwest Cape 345/161 kV sub and new lines2306 $ -4.25%$0.00 $ -9.64%$0.00$0$0.00 $ -0 2Annual Totals$8,089,316$0$8,089,316 3Rev. Req. Adj For Attachment O$8,089,316

13. 13 2014 SIGNIFICANT TRANSMISSION PROJECTS Transmission Lines Project NameTotal Cost Montgomery - Spencer Creek - Sub T$63 Million Mason - Labadie$15 Million Thomas Hill - Adair$9 Million Labadie - Montgomery$9 Million

14. 14 FUTURE SIGNIFICANT TRANSMISSION PROJECTS Project NameTotal CostISDMTEPMISO ID#MTEP Description Cape Girardeau Electric Reliability Project (Northwest Cape Area 345/161 kV Substation) $60 M2016MTEP112306 Install 560 MVA, 345/161 kV Transformer. Provide 345 kV supply from 11 mile 345 kV line extension from Lutesville Substation

15. 15 MISO WEB LINKS Transmission Pricing - Attachments O, GG & MM Information https://www.misoenergy.org/MarketsOperations/TransmissionSettlement s/Pages/TransmissionPricing.aspxhttps://www.misoenergy.org/MarketsOperations/TransmissionSettlement s/Pages/TransmissionPricing.aspx Ameren OASIS http://www.oasis.oati.com/AMRN/index.html MTEP 14 https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEP14.aspxhttps://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEP14.aspx MTEP 15 https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEP15.aspxhttps://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEP15.aspx Schedule 26 & 26-A Indicative Charges https://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEPStudies.aspxhttps://www.misoenergy.org/Planning/TransmissionExpansionPlanning/ Pages/MTEPStudies.aspx

16. QUESTIONS?

17. 17 Appendix Supplemental Background Information

18. 18 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 is currently building a new local reliability project in Southeast Missouri. Ameren Missouri is the only MISO Transmission Owner in the AMMO pricing zone.

19. 19 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

20. 20 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 One additional project under construction 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.

21. 21 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

22. 22 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

23. 23 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