MISO selects consortium of Ameren, GridLiance, Dairyland, Illinois Municipal Electric Agency to deliver major grid-bolstering projects in Illinois

Rhea-AI Summary

Ameren (NYSE:AEE) subsidiary Ameren Transmission Company of Illinois, with GridLiance Heartland, Dairyland Power and Illinois Municipal Electric Agency, was selected by MISO to develop, build, operate and maintain two major 765-kV transmission projects in Illinois.

The STIW project spans about 149 miles with an estimated cost of $940 million, while the WIIL project covers 88 miles plus a new 765/345-kV substation at an estimated $718 million. Ownership stakes are 43% ATXI, 43% GridLiance, 11% Dairyland and 3% IMEA, with expected in-service dates in 2034 following regulatory review.

Positive

• ATXI awarded 43% ownership in STIW and WIIL transmission projects
• Participation in MISO-estimated $940 million STIW project
• Participation in MISO-estimated $718 million WIIL project
• Long-term project visibility with expected 2034 in-service dates
• Consortium role to develop, build, operate and maintain both projects

Negative

• None.

News Market Reaction – AEE

+1.51%

+1.51% Session close to close

In the May 19 session, AEE gained 1.51%, reflecting a mild positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

This announcement detailed MISO’s selection of an Ameren-led consortium to build two major 765-kV tr...

Analysis

This announcement detailed MISO’s selection of an Ameren-led consortium to build two major 765-kV transmission projects in Illinois, with estimated costs of $940 million and $718 million and expected in-service dates in 2034. The projects extend Ameren’s focus on regulated grid investment seen in recent capital-raising and earnings disclosures. Investors may track regulatory approvals, construction milestones, and how these projects interact with existing capital expenditure plans and the company’s DRPlus equity program under the effective S-3ASR registration.

Key Figures

STIW project cost: $940 million STIW line length: 149 miles WIIL project cost: $718 million +5 more

8 metrics

STIW project cost $940 million MISO estimated cost for STIW 765-kV transmission project

STIW line length 149 miles Approximate length of two new 765-kV lines in STIW project

WIIL project cost $718 million MISO estimated cost for WIIL 765-kV transmission project

WIIL line length 88 miles Total span of two new 765-kV lines in WIIL project

WIIL connector length 1.5 miles Segment from Woodford County Substation toward Collins Substation

ATXI ownership stake 43% Ownership share in both STIW and WIIL transmission projects

GridLiance ownership stake 43% Ownership share in both STIW and WIIL transmission projects

Dairyland ownership stake 11% Ownership share in both STIW and WIIL transmission projects

Historical Context

5 past events · Latest: May 15 (Positive)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
May 15	Dividend declaration	Positive	-3.0%	Board declared a $0.75 quarterly common dividend and preferred dividends.
May 05	Earnings release	Positive	-1.8%	Q1 2026 earnings and EPS rose versus 2025 and guidance was reaffirmed.
Apr 15	Earnings webcast	Neutral	+1.4%	Company scheduled its Q1 2026 earnings webcast and provided access details.
Feb 26	Debt offering	Neutral	+1.1%	Priced $400M of 5.00% senior notes due 2036 to refinance debt.
Feb 23	Utility bond issue	Neutral	+0.1%	Ameren Missouri priced $900M of first mortgage bonds for refinancing and capex.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Recent history shows occasional share-price weakness on otherwise constructive news, including dividends and stronger earnings, suggesting investors have sometimes sold into positive announcements.

Recent Company History

Over the last six months, Ameren’s news flow has centered on capital markets activity, earnings and shareholder returns. In February 2026, the company priced senior notes and Ameren Missouri mortgage bonds to support capital needs. First-quarter 2026 results on May 5 showed higher earnings and reaffirmed guidance, yet the stock slipped 1.84%. A quarterly dividend declaration on May 15 coincided with a 2.96% decline. Today’s large MISO transmission award extends that infrastructure-focused trajectory.

Key Terms

765-kilovolt (kV), transmission lines, substation, in-service dates

4 terms

765-kilovolt (kV) technical

"The Sub T – Iowa/Illinois State Line – Woodford County (STIW) and Woodford County – Illinois/Indiana State Line (WIIL) projects are the foundation of a new 765-kilovolt (kV) backbone"

A 765-kilovolt (kV) line is a very high-voltage electricity transmission circuit used to move large amounts of power over long distances with lower energy loss, like a multi-lane highway for electricity. For investors, such lines signal major infrastructure projects that involve substantial capital spending, regulatory permits and long-term revenue or cost impacts, and they affect grid reliability, asset lifespan and potential returns on utility or transmission investments.

transmission lines technical

"The STIW project includes the construction of two new 765-kV transmission lines spanning approximately 149 miles."

High-voltage towers and cables that carry electricity from power plants to cities and substations, like highways that move energy rather than cars. For investors, transmission lines are long-lived, capital-intensive assets whose condition, capacity and regulatory treatment affect utility revenues, reliability and the ability to connect new generation; bottlenecks or upgrades can change costs, permit timelines and future returns.

substation technical

"The WIIL project includes the construction of two new 765-kV transmission lines that span a total of 88 miles and the construction of a new 765/345-kV substation."

A substation is a fenced facility on the electricity network where equipment changes the voltage, routes power, and protects the grid so electricity can move safely and reliably from generation to homes and businesses. Investors care because substations are critical pieces of infrastructure: they affect service reliability, grid capacity and upgrade costs, and can influence the value and operating risk of utilities, real estate near outages, and companies in the energy supply chain.

in-service dates technical

"Both projects have expected in-service dates of 2034, following the regulatory review process"

In-service dates are the calendar day when an asset, piece of equipment, or service is officially put into regular use and begins performing its intended function. For investors, this matters because it marks when the item can start generating revenue, trigger accounting actions like depreciation or amortization, and affect tax or regulatory reporting—similar to the moment a new store opens and starts counting sales and expenses.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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ST. LOUIS, May 19, 2026 /PRNewswire/ -- The Midcontinent Independent System Operator (MISO) has selected a consortium of Ameren Transmission Company of Illinois (ATXI), a subsidiary of Ameren Corporation (NYSE: AEE); GridLiance Heartland, LLC, a subsidiary of NextEra Energy Transmission, LLC; Dairyland Power Cooperative; and the Illinois Municipal Electric Agency (IMEA) to develop, build, operate and maintain two major transmission projects. ATXI and GridLiance will lead the development of these projects, while Dairyland and IMEA will own a portion of both projects when they are placed in service.

The Sub T – Iowa/Illinois State Line – Woodford County (STIW) and Woodford County – Illinois/Indiana State Line (WIIL) projects are the foundation of a new 765-kilovolt (kV) backbone that will deliver safe, reliable and cost-competitive energy to serve Midwest communities for decades to come. 

The STIW project includes the construction of two new 765-kV transmission lines spanning approximately 149 miles. One 765-kV line will run from the Woodford County Substation west to the Iowa/Illinois state line, and the other 765-kV line will continue west from the Iowa/Illinois state line to the Sub T Substation in Iowa. The STIW project has a MISO estimated cost of $940 million.

The WIIL project includes the construction of two new 765-kV transmission lines that span a total of 88 miles and the construction of a new 765/345-kV substation. One 765-kV line will run east from the existing Woodford County Substation in central Illinois to the Illinois/Indiana state line. The other 765-kV line will run northeast from the Woodford County Substation for approximately 1.5 miles toward the existing Collins Substation before interconnecting with a separate 765-kV line segment. The WIIL project has a MISO estimated cost of $718 million.

ATXI, GridLiance, Dairyland and IMEA will have ownership stakes in both projects of 43%, 43%, 11% and 3%, respectively.

"We are committed to delivering infrastructure that strengthens the grid and creates value for customers both now and over the long term," said Shawn Schukar, chairman and president of ATXI. "The collaboration between ATXI, GridLiance, Dairyland and IMEA enables us to work with our local communities, regulators and local contractors to effectively and efficiently build this valuable transmission system expansion while supporting the growth in our region."

"These projects are critical to building a stronger, more resilient transmission backbone for the Midwest," said Matt Valle, president of NextEra Energy Transmission, LLC. "We're proud to work with ATXI, Dairyland and IMEA to deliver needed energy infrastructure to enhance reliability, support growing energy needs and benefit communities for decades to come."

"As a critical services provider, Dairyland is pleased to be part of a consortium that will help ensure the reliability and flexibility of the transmission system in the Upper Midwest for current and future generations," said Ben Porath, Dairyland executive vice president and chief operating officer.

"Increasing transmission capacity on the grid is critical to improving resiliency, integrating new resources and supporting long‑term economic developments," said IMEA CEO and President Doug Brown. "The Illinois Municipal Electric Agency is proud to be a partner on these projects."

Both WIIL and STIW are competitive projects in MISO's Long Range Transmission Planning Tranche 2.1 Portfolio, which was originally approved in December 2024. Both projects have expected in-service dates of 2034, following the regulatory review process and thorough stakeholder and community engagement.

About Ameren Corporation
St. Louis-based Ameren Corporation powers the quality of life for 2.5 million electric customers and more than 900,000 natural gas customers in a 64,000-square-mile area through its Ameren Missouri and Ameren Illinois rate-regulated utility subsidiaries. Ameren Illinois provides electric transmission and distribution services and natural gas distribution services. Ameren Missouri provides electric generation, transmission and distribution services, as well as natural gas distribution services. Ameren Transmission Company of Illinois develops, owns and operates rate-regulated regional electric transmission projects in the Midcontinent Independent System Operator, Inc. For more information, visit Ameren.com, or follow us at @AmerenCorp, Facebook.com/AmerenCorp, or LinkedIn.com/company/Ameren.

About NextEra Energy Transmission
NextEra Energy Transmission, LLC is North America's leading competitive transmission company. With more than 3,200 miles of transmission lines in operation and development in 19 states and Canada, the company is strengthening and modernizing the electric grid to meet the country's growing energy needs. NextEra Energy Transmission owns, develops, finances, constructs, operates and maintains transmission assets across the continent. The company operates through its regional subsidiaries to integrate diverse energy sources. NextEra Energy Transmission, LLC is a subsidiary of Juno Beach, Florida-based NextEra Energy, Inc. For more information, visit www.NextEraEnergyTransmission.com. 

About Dairyland Power Cooperative
Headquartered in La Crosse, Wis., Dairyland provides the wholesale electrical requirements for 24 distribution cooperatives and 27 municipal utilities. These cooperatives and municipals, in turn, supply the energy needs of over 800,000 people in a four-state service area. Dairyland delivers electricity via 3,708 miles of transmission lines and 400 distribution substations located throughout the system's 44,500 square mile service area. Visit www.DairylandPower.com.

About Illinois Municipal Electric Agency
The Illinois Municipal Electric Agency (IMEA) is a not-for-profit unit of local government created in 1984 that provides wholesale power supply and related services to municipal electric systems across Illinois. IMEA is currently comprised of 32 municipal electric systems, each of which owns and operates its own electric distribution system, with some also operating local power generation plants. Through collective action, IMEA helps its member communities secure affordable, reliable and sustainable energy while preserving local control over rates, services and utility-related solutions. For more information, visit www.imea.org.

View original content to download multimedia:https://www.prnewswire.com/news-releases/miso-selects-consortium-of-ameren-gridliance-dairyland-illinois-municipal-electric-agency-to-deliver-major-grid-bolstering-projects-in-illinois-302775548.html

SOURCE Ameren Corporation

FAQ

What MISO transmission projects were awarded to Ameren (NYSE:AEE) and partners in Illinois in May 2026?

MISO selected a consortium including Ameren’s ATXI to deliver the STIW and WIIL 765-kV transmission projects in Illinois. According to the companies, the group will develop, build, operate and maintain these new high-voltage lines forming a key Midwest transmission backbone.

How large are the STIW and WIIL transmission projects involving Ameren (AEE) in miles and estimated cost?

The STIW project includes about 149 miles of 765-kV lines with a MISO estimated cost of $940 million. According to MISO, the WIIL project spans 88 miles plus a new substation, with an estimated cost of $718 million.

What ownership stake will Ameren’s ATXI hold in MISO’s STIW and WIIL transmission projects?

ATXI is expected to own 43% of both the STIW and WIIL projects. According to the consortium, GridLiance will also own 43%, Dairyland 11% and Illinois Municipal Electric Agency 3%, sharing economic interest in these major Illinois transmission assets.

When are the STIW and WIIL transmission projects involving Ameren (AEE) expected to enter service?

Both STIW and WIIL are expected to be in service in 2034. According to the companies, these timelines follow completion of the regulatory review process and extensive stakeholder and community engagement within MISO’s Long Range Transmission Planning portfolio.

How will the new 765-kV transmission backbone benefit Midwest energy customers and communities?

The 765-kV backbone is intended to deliver safe, reliable, cost-competitive energy across Midwest communities. According to project partners, increased transmission capacity should enhance grid resiliency, support growing energy needs, integrate new resources and help meet long-term regional economic development demands.

What is the role of each partner alongside Ameren (AEE) in the STIW and WIIL projects?

ATXI and GridLiance will lead development of the STIW and WIIL projects, while Dairyland and IMEA will own portions. According to the consortium, all four will collaborate with communities, regulators and contractors to build and operate these Illinois transmission lines.