Upstage releases Solar Open 2 — a 250B open-weight model built for long-horizon agent work

Korea's Upstage released Solar Open 2 on July 23, 2026 — a 250-billion-parameter mixture-of-experts model (15B active) with a 1M-token context window, tuned for autonomous agent tasks rather than chat. Artificial Analysis independently measured it at 98% on the Tau2 agent benchmark, ahead of DeepSeek V4 Pro, and its Apache-based license permits commercial use.

What it means A self-hostable, independently benchmarked alternative to closed agent APIs — runnable on two H200s when quantized.