NorthWestern Energy
NorthWestern Energy is a regulated U.S. utility supplying electricity and natural gas to customers in Montana, South Dakota, and Nebraska.
Last updated October 17, 2026
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Overview
NorthWestern Energy, formally NorthWestern Energy Group, Inc. (also known as NorthWestern Corporation), is a publicly traded American utility headquartered in Sioux Falls, South Dakota. Its regulated businesses provide electricity and natural gas service across Montana, South Dakota, and Nebraska, supported by generation, transmission, distribution, and related energy infrastructure. The company serves residential, commercial, industrial, and governmental customers, with its operations shaped by state utility commissions and by the capital requirements of maintaining long-lived energy networks. The company was established in 2002 and developed its current identity through the consolidation and ownership of utility businesses in the northern Great Plains and northern Rocky Mountain region. Its South Dakota operations are historically associated with NorthWestern Public Service Company, whose operational headquarters were in Huron, South Dakota, while the corporate headquarters are in Sioux Falls. The company also operates in Nebraska and Montana, where its business has a particularly important historical connection to the former Montana Power Company. NorthWestern entered the Montana market around 2000 after Montana legislation allowed the electric utility industry to be unbundled. The restructuring separated generation from other parts of the electricity business, and generation assets formerly associated with Montana Power were acquired by outside investors led by PP&L Resources. The resulting exposure to wholesale or “spot” energy prices contributed to continuing dissatisfaction in Montana and complicated later strategic developments. In 2014, NorthWestern acquired hydroelectric dams that had originally been part of Montana Power from PPL Corporation for approximately $900 million, strengthening its ownership of Montana generation assets and reducing reliance on external power purchases. NorthWestern’s public profile has also been affected by litigation and operational incidents. A 2003 securities class action alleged that Northwestern Corporation inflated its stock price through material omissions and misleading statements; a $41 million settlement fund was established in 2005. In 2009, a gas explosion in Bozeman, Montana, destroyed several businesses and killed one person. Owners of the damaged businesses subsequently sued the company. In August 2025, NorthWestern and Black Hills Corporation announced an agreement to merge in an all-stock transaction valued at approximately $15.4 billion. Under the proposed structure described in the announcement, NorthWestern shareholders would hold about 46 percent of the combined company, and NorthWestern chief executive Brian Bird would lead the merged organization. Completion remains subject to customary approvals and the closing conditions described in the announcement. Until the transaction closes, NorthWestern remains an independent, publicly listed utility operating under the NorthWestern Energy brand.
History
NorthWestern Energy’s present-day business grew out of utility operations in the northern Great Plains and northern Rocky Mountain region. The company was founded in 2002 and is headquartered in Sioux Falls, South Dakota. Its South Dakota operations have historical links to NorthWestern Public Service Company, whose operating headquarters were located in Huron. The company also established utility operations in Nebraska and Montana, creating a multistate regulated platform centered on electricity and natural gas delivery. The Montana business has roots in the former Montana Power Company. Around 2000, Montana enacted legislation permitting the electric utility industry to be unbundled. The restructuring separated generation assets from other portions of the utility system. Outside investors led by PP&L Resources acquired Montana Power’s generation assets, leaving the remaining utility territory more exposed to wholesale market conditions and potentially volatile spot prices. Those conditions contributed to persistent public and regulatory dissatisfaction in Montana. The Montana Public Service Commission later cast the sole opposing vote that effectively prevented a proposed sale of NorthWestern to Australia’s Babcock & Brown. A major later development was NorthWestern’s 2014 purchase of hydroelectric dams that had originally been part of Montana Power. The assets were acquired from PPL Corporation for approximately $900 million. The transaction increased NorthWestern’s control of in-state generation resources and gave the company a larger physical asset base within its Montana operations. For a regulated utility, ownership of generation can affect the balance between internally controlled supply and purchases from wholesale markets, although the economic and regulatory treatment of the assets remains subject to applicable proceedings. NorthWestern has also faced legal and operational challenges. In March 2003, a securities class action was filed against Northwestern Corporation. The allegations concerned statements and omissions that plaintiffs said artificially inflated the company’s share price. A $41 million settlement fund was established in 2005. Separately, a gas explosion occurred in Bozeman, Montana, in 2009. The incident destroyed several businesses and caused one death. By November of that year, multiple owners of destroyed businesses had filed suits against the company. By 2019, the company reportedly served approximately 718,000 customers across South Dakota, Nebraska, and Montana. Its activities included regulated electricity and natural-gas service, operation and maintenance of distribution infrastructure, transmission-related assets, and ownership or management of generation resources. The company’s customer base and asset portfolio make it dependent on regulatory approvals, reliability investment, fuel and power-market conditions, environmental requirements, and regional economic growth. In August 2025, NorthWestern and Black Hills Corporation announced an agreement to merge through an all-stock transaction valued at approximately $15.4 billion. The proposed combination would give NorthWestern shareholders about 46 percent of the combined company, while Brian Bird, NorthWestern’s chief executive, would run the merged organization. The announcement represents a potential strategic transformation from two separately traded regional utilities into a larger combined energy company. The transaction is subject to the approvals and closing conditions specified by the parties; until completion, NorthWestern remains an independent listed company.
- 2025
Merger agreement with Black Hills Corporation
[1]NorthWestern and Black Hills announced an all-stock merger agreement valued at approximately $15.4 billion.
- 2019
Reported customer base reaches approximately 718,000
[1]Reference material reported that NorthWestern served approximately 718,000 customers across its three-state service territory.
- 2014
Purchase of former Montana Power dams
[1]NorthWestern bought hydroelectric dams originally associated with Montana Power from PPL Corporation for approximately $900 million.
- 2009
Bozeman gas explosion
[1]A gas explosion in Bozeman, Montana, destroyed several businesses and killed one person, followed by litigation from affected property owners.
- 2005
Securities litigation settlement fund established
[1]A settlement fund totaling $41 million was established in connection with the securities class action.
- 2003
Securities class action filed
[1]A class action alleged that Northwestern Corporation had used material omissions and misleading statements that inflated its stock price.
- 2002
NorthWestern Energy founded
[1]NorthWestern Energy was established as a multistate utility serving customers in the northern Rocky Mountain and Great Plains regions.
- 2000
Montana utility restructuring and acquisition of generation assets
[1]After Montana legislation allowed electric-industry unbundling, outside investors led by PP&L Resources acquired generation assets associated with Montana Power, changing the structure of the state’s electricity market.
Products and positioning
Regulated electric and natural-gas utility serving customers in the northern Rocky Mountain and Great Plains regions.
Regulated electricity
Electricity service
NorthWestern provides regulated electricity service to customers in Montana, South Dakota, and Nebraska. The offering covers the delivery of electricity through local distribution networks and is supported by generation, transmission, system operations, maintenance, reliability investment, and customer billing. Rates and service obligations are generally governed by state utility regulation.
Regulated natural gas
Natural gas service
The company supplies natural gas through regulated distribution operations in its service territory. Its gas business serves households, businesses, and other customers through pipeline and distribution infrastructure, with safety, reliability, procurement, and rate-setting subject to applicable state oversight.
Power generation · 2014
Hydroelectric generation
NorthWestern owns generation assets in Montana, including hydroelectric dams acquired from PPL Corporation in 2014. These assets form part of the company’s electricity supply portfolio and represent a strategic link to the former Montana Power generation system.
Controversies
2009
Bozeman gas explosion and subsequent lawsuits
A gas explosion in Bozeman, Montana, destroyed several businesses and killed one person. Numerous owners of destroyed businesses subsequently sued the company.
2003
Securities disclosure litigation
A securities class action alleged that Northwestern Corporation’s omissions and misleading statements artificially inflated its stock price. The matter resulted in a $41 million settlement fund established in 2005.
Brand decisions
2025
Agree to combine with Black Hills CorporationM&ABackground
NorthWestern and Black Hills pursued a larger combined utility platform through a stock-based transaction.
Action taken
The companies agreed to an all-stock merger valued at approximately $15.4 billion. NorthWestern shareholders would receive about 46 percent of the combined company, and Brian Bird was designated to lead the merged organization.
Aftermath
The announced transaction remains subject to required approvals and closing conditions. NorthWestern remains separately listed unless and until the merger is completed.
Announced transaction value. $15.4 billion (August 2025)
2014
Acquire former Montana Power hydroelectric damsM&ABackground
NorthWestern sought to expand its owned generation portfolio in Montana and acquire assets historically associated with Montana Power.
Action taken
The company purchased the dams from PPL Corporation for approximately $900 million.
Aftermath
The purchase increased NorthWestern’s ownership of Montana generation resources and reduced the asset portfolio’s separation from the former Montana Power system.
Purchase price. $900 million (2014)
Recent events
- 2025
NorthWestern and Black Hills agree to proposed all-stock merger[1]
M&A · Other
NorthWestern Energy and Black Hills Corporation agreed to combine in an all-stock transaction valued at approximately $15.4 billion. The proposed ownership split would give NorthWestern shareholders about 46 percent of the combined company, with NorthWestern CEO Brian Bird expected to lead the organization.
- 2014
NorthWestern acquires former Montana Power dams from PPL[1]
M&A
NorthWestern purchased hydroelectric dams originally associated with Montana Power from PPL Corporation for approximately $900 million, expanding its ownership of generation assets in Montana.
- 2005
Securities class action settlement involving Northwestern Corporation[1]
Lawsuit · Other
A securities class action filed in 2003 alleged that the company had artificially inflated its stock price through omissions and materially misleading statements. A settlement fund of $41 million was established in 2005.
Sources3 sources
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