Realta Fusion – founded in 2022 and based in Madison, Wisconsin – is an early-stage fusion company spun out of the University of Wisconsin–Madison. The company is developing a fusion system based on a magnetic mirror concept, specifically the Wisconsin High-field Axisymmetric Mirror (WHAM). WHAM achieved its first plasma in July 2024 as part of a public-private collaboration involving Realta and UW–Madison.

Realta Fusion aims to develop a commercially viable fusion reactor by the 2030s for applications such as industrial heat and hydrogen production.