Upstage, a Korean AI company, released Solar Open 2, an open-weight large language model designed for multistep tasks, on Thursday. The model's weights were published on Hugging Face with a technical report, developed under a government-backed project where Upstage is the lead organization. Solar Open 2 has 250 billion parameters but activates only 15 billion at a time using a "mixture of experts" structure, can process up to 1 million tokens of context, and can run on two Nvidia H200 chips when compressed. The company said the model outperformed DeepSeek's V4 Flash, Mistral's Medium 3.5 and Cohere's Command A+ on benchmarks, and improved more than 20 points over its predecessor on reasoning, math and coding tests. In Korean-language benchmarks, it also outperformed OpenAI's GPT-5.4 mini and Anthropic's Claude Haiku 4.5. The model is released under the Apache 2.0-based Upstage Solar License, permitting commercial use. Upstage plans to apply it to the Daum portal and its Tamnlee AI agent platform, and expand use across finance, law, health care and other industries.