NuScale Power Corporation (NYSE: SMR) experienced a significant after-hours plunge of 5.18% following the release of its fourth quarter and full year 2025 financial results.

The company reported a decline in annual revenue to $31.5 million, down from $37.0 million in the previous year. More concerning to investors was the dramatic increase in general and administrative expenses, which soared to $609.8 million for the year, a sevenfold increase that included a $507.4 million milestone payment related to its partnership agreement with ENTRA1 Energy. This contributed to a substantial net loss of $664.5 million for the fiscal year.

Additionally, the company is facing a securities class action lawsuit alleging misleading statements and omissions about the experience and capabilities of ENTRA1 Energy and related parties involved in NuScale's commercialization strategy. The combination of disappointing financial performance and legal challenges appears to have driven the after-hours sell-off.