StepFun's Step 5 Preview reaches the cost/intelligence frontier at a third of Kimi K3's price.

Released September 18 by a lab not previously counted as frontier. Artificial Analysis scores it 44 on the Intelligence Index, matching Kimi K3 max, at $1.00 per million input and $2.70 per million output with a 95% cache discount, 99.8 output tokens per second, 1M context. Artificial Analysis Closed source, so unlike the recent Chinese open-weight releases there's nothing to run locally, which is the caveat on the "another Chinese lab reached the frontier" framing.