NorthWestern Energy Group, Inc. is a utility company that serves South Dakota, Nebraska, and Montana that is based in Sioux Falls.

Out of state investors (led by PP&L Resources) then immediately acquired the generation assets of Montana Power, leaving that part of the territory vulnerable to high "spot" prices on the energy market (creating some chronic discontent that led the Montana Public Service Commission to submit the one "no" vote that effectively nullified a potential sale of NorthWestern to Babcock & Brown of Australia).

In 2014, NorthWestern purchased the dams that were originally part of Montana Power for $900 Million from PPL Corporation.

[2] In March, 2003, a class action was filed against Northwestern Corp, claiming that defendants artificially inflated the stock price through material omissions and materially false and misleading statements.

[3] In March 2009, NorthWestern Energy was involved with a gas explosion in Bozeman, Montana.