Black Hills Corp. and NorthWestern Energy Group, Inc. announced an all-stock merger that will create a regional regulated electric and natural gas utility company with a market capitalization of approximately $7.8 billion and a combined enterprise value of $15.4 billion. 

Under the terms of the agreement, NorthWestern shareholders will receive 0.98 shares of Black Hills for each share they own, representing about a 4% premium since negotiations began in March 2025. Upon completion, Black Hills shareholders will hold roughly 56% of the combined company, while NorthWestern shareholders will own about 44%. 

The new company, headquartered in Rapid City, SD, will serve approximately 2.1 million customers across Arkansas, Colorado, Iowa, Kansas, Montana, Nebraska, South Dakota, and Wyoming. Its electric utility operations will span 38,000 miles of electric lines with 2.9 GW of owned generation capacity, while its natural gas utility will serve 1.4 million customers across 59,000 miles of gas lines. 

Black Hills president and CEO Linn Evans, who will retire after the close, said the merger would bring greater financial strength and scale to meet the demands of the energy transition. NorthWestern president and CEO Brian Bird, who will lead the combined company, emphasized the aligned cultures and skilled workforces that will support integration. 

The leadership team will also include Marne Jones (COO), Crystal Lail (CFO), and Kimberly Nooney (chief integration officer). The merged utility targets long-term EPS growth of 5% to 7% and expects to be accretive to EPS in the first year post-closing. 

The deal is expected to close within 12 to 15 months, subject to regulatory and customary approvals. Goldman Sachs & Co. LLC is serving as exclusive financial advisor to Black Hills, and Faegre Drinker Biddle & Reath LLP is serving as legal advisor. Greenhill, a Mizuho affiliate, is serving as exclusive financial advisor to NorthWestern, and Morgan, Lewis & Bockius LLP is serving as legal advisor.