Korean AI lab Upstage has released Solar Pro 4, scoring 42 on the Artificial Ana — Intel

Terms in this piece · Glossary

reasoning model — A model trained to think — generating extended internal reasoning before answering — trading time and tokens for accuracy on hard problems.
token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
context window — The maximum amount of text a model can consider at once — its working memory for the current conversation or task.
AI agent — An AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.

Why it matters

A 27 point jump concentrated in agentic and long- work, at $0.30/$1.20 per million , puts a credible cheaper option on the table for workloads.

Key quotes

“Solar Pro 4 is @upstageai's new proprietary flagship reasoning model, replacing Solar Pro 3 from April 2026. At 42 on the Intelligence Index it sits alongside Inkling (xhigh, 42) and just behind MiMo-V2.5-Pro (43), and shows a 27-point increase over Solar Pro 3.”
ArtificialAnlys

“Solar Pro 4’s largest improvements on Solar Pro 3 are on agentic and long context work. Terminal-Bench v2.1 improves from 12% to 57%, AA-LCR from 31% to 71%, and τ³-Banking from 9% to 23%.”
ArtificialAnlys

“AA-Omniscience improvement from -53 to -1 was driven by abstaining on more questions. Solar Pro 4 attempts only 41% of questions against 92% for Solar Pro 3, and its hallucination rate is 24%, higher than Command A+ (14%) and MiniMax-M3 (18%), and a vast improvement from Solar Pro 3’s 88%.”
ArtificialAnlys

“Solar Pro 4 is more token efficient than Solar Pro 3, though still verbose for its intelligence level. It uses 43k output tokens per Intelligence Index task, around 17% fewer than Solar Pro 3's 52k.”
ArtificialAnlys

“The intelligence gain comes with a hit to latency. Solar Pro 4 takes 9.5 minutes to complete an average Intelligence Index task, against 6.9 minutes for Solar Pro 3, despite using fewer output tokens per task.”
ArtificialAnlys