Yesterday, we announced third quarter 2021 earnings of $1.65 per share.
Our earnings were up $0.18 per share from the same time period in 2020.
Our 2021 earnings guidance range is now $3.75 per share to $3.95 per share compared to our original guidance range of $3.65 per share to $3.85 per share.
In late March, Ameren Missouri filed a request for a $299 million increase in annual electric service revenues and a $9 million increase in annual natural gas service revenues with the Missouri Public Service Commission.
In our Illinois Electric business, we have requested a $59 million base rate increase in our required annual electric distribution rate filing.
As we have discussed with you in the past, MISO completed a study outlining the potential road map of transmission projects through 2039.
Under MISOs Future one scenario, which is the scenario that resulted in an approximate 60% carbon emissions reduction below 2005 levels by 2039 and MISO estimates approximately $30 billion of future transmission investment would be necessary in the MISO footprint.
Under its Future three scenario, which resulted in an 80% reduction in carbon emissions below 2005 levels by 2039, MISO estimates approximately $100 million of transmission investment in the MISO footprint would be needed.
Beginning with environmental stewardship, last September, Ameren announced its transformation plan to achieve net-zero carbon emissions by 2050 across all of our operations in Missouri and Illinois.
This plan includes interim carbon emission reduction targets of 50% and 85% below 2005 levels in 2030 and 2040, respectively, and is consistent with the objectives of the Paris Agreement and limiting global temperature rise to 1.5 degrees Celsius.
Turning to page 10, you will go down further on this key element.
Our strong sustainable growth proposition is driven by a robust pipeline of investment opportunities over $40 billion over the next decade that will deliver significant value to all of our stakeholders and making our energy grid stronger, smarter and cleaner.
Our outlook through 2030 does not include significant infrastructure investments for electrification at this time.
Moving to page 11.
Another key element of our sustainable growth proposition is the five-year earnings-per-share growth guidance we issued in February, which included a 6% to 8% compound annual earnings-per-share growth rate from 2021 to 2025.
Importantly, our five-year earnings and rate base growth projections do not include 1,200 megawatts of incremental renewable investment opportunities outlined in Ameren Missouris Integrated Resource Plan.
Finally, turning to page 12.
And during the past 20 years, Marty has demonstrated strong operational, financial, regulatory and strategic acumen.
Yesterday, we reported third quarter 2021 earnings of $1.65 per share compared to $1.47 per share for the year ago quarter.
Turning to Ameren Missouri, our largest segment increased $0.27 per share, driven primarily by a change in seasonal electric rate design, resulting from the March 2020 rate order, which provided for lower winter rates in May and higher summer rates in September rather than the blended rates used in both months in 2020.
Higher electric retail sales also increased earnings by approximately $0.10 per share largely due to continued economic recovery in this years third quarter compared to the unfavorable impacts of COVID-19 in the year ago period as well as higher electric retail sales driven by warmer-than-normal summer temperatures in the period compared to near-normal summer temperatures in the year-ago period.
Increased investments in infrastructure and wind generation eligible for plant and service accounting and the renewable energy standard rate adjustment mechanism, or RESRAM, positively impacted earnings by $0.07 per share.
The timing of tax expense, which is not expected to materially impact full year results increased earnings by $0.03 per share.
Higher operations and maintenance expense decreased earnings by $0.04 per share in 2021 compared to the third quarter of 2020, which was affected by COVID-19 and remained flat year-to-date driven by disciplined cost management.
Finally, the amortization of deferred income taxes related to the fall 2020 Callaway Energy Center scheduled refueling and maintenance outage also decreased earnings $0.02 per share.
Ameren Transmission earnings increased $0.03 per share year-over-year, reflecting increased infrastructure investment.
Earnings for Ameren Illinois Natural Gas decreased $0.04 per share.
Ameren parent and other results decreased $0.08 per share compared to the third quarter of 2020, primarily due to the timing of income tax expense, which is not expected to materially impact full year results.
Weather-normalized kilowatt hour sales to Illinois residential customers decreased 0.5%.
And weather-normalized kilowatt hour sales to Illinois commercial and industrial customers increased 2.5% and 1.5%, respectively.
Turning to page 15.
As Warner noted, due to the solid execution of our strategy, we now expect 2021 diluted earnings to be in the range of $3.75 per share to $3.95 per share, an increase from our original guidance range of $3.65 per share to $3.85 per share.
Moving to page 16 for an update on regulatory matters.
On March 31, we filed for a $299 million electric revenue increase with the Missouri Public Service Commission.
The request includes a 9.9% return on equity, a 51.9% equity ratio and a September 30, 2021 estimated rate base of $10 billion.
Missouri PSC staff recommended a $188 million revenue increase including a return on equity range of 9.25% to 9.75% and an equity ratio of 50% based on Ameren Missouris capital structure at June 30, 2021, which will be updated to use the capital structure as of September 30, 2021.
Turning to Page 17.
In addition to the electric filing on March 31, we filed for a $9 million natural gas revenue increase within the Missouri PSC.
The request includes a 9.8% return on equity, a 51.9% equity ratio and a September 30, 2021 estimated rate base of $310 million.
Missouri PSC staff recommended a $4 million revenue increase, including a return on equity range of 9.25% to 9.75% and an equity ratio of 50.32% based on Ameren Missouris capital structure at June 30, 2021, which will be updated to use of the cash flow structure as of September 30, 2021.
Moving to page 18, Ameren Illinois regulatory matters.
In August, the ICC staff recommended a $58 million base rate increase compared to our request of $59 million base rate increase.
Turning now to Page 19.
The return on equity, which will be determined by the Illinois Commerce Commission, may impacted by plus or minus 20 to 60 basis points based on the utilitys ability to meet certain performance metrics related to items such as reliability, customer service and supplier diversity.
The plan also allows for the use of year-end rate base and an equity ratio up to 50% with an higher equity ratio subject to approval by the ICC.
Theres a cap on the true-up, which may not exceed 105% of the revenue requirement and excludes variation from certain forecasted costs.
The legislation also allows for two utility-owned solar and/or battery storage pilot projects to be located near Peoria and East St. Louis at a cost not to exceed $20 million each.
Moving to page 20 for a financing update.
In order for us to maintain our credit earnings and a strong balance sheet while we fund our robust infrastructure plan and consistent with prior guidance as of August 15, we have completed the issuance of approximately $150 million of common equity through our at-the-market or ATM program that was established in May.
Further, approximately $30 million of equity outlined for 2022 have been sold year-to-date under the programs forward sales agreement.
Together with the issuance under our 401(k) and DRPlus program, our $750 million ATM equity program is expected to support equity needs through 2023.
Moving now to page 21.
Beginning with our natural gas business, heading into the winter season, Ameren is approximately 75% hedged, and Ameren Missouri is approximately 85% hedged based on normal seasonal sales.
Approximately 60% of Illinois winter supply of natural gas was bought this summer at lower prices and is being stored in the companys 12 underground storage fields.
Both companies are 100% volumetrically hedged based on maximum seasonal sales.
Turning to page 22.
As a result, we expect energy efficiency performance incentives to be approximately $0.04 per share higher than 2021.
Further, our return to normal weather in 2022 would decrease Ameren Missouri earnings by approximately $0.04 compared to 2021 results to date, assuming normal weather in the last quarter of the year.
The allowed ROE under the formula will be the average 2022 30-year treasury yield plus 5.8%.
For Ameren Illinois Natural Gas, earnings are expected to benefit from new delivery service rates effective late January 2021 as well as an increase in infrastructure investments qualifying for rider treatment that were in the current allowed ROE of 9.67%.
And Lastly, turning to page 23, were well positioned to continue executing our plan.

Summary:
Our 2021 earnings guidance range is now $3.75 per share to $3.95 per share compared to our original guidance range of $3.65 per share to $3.85 per share.