Open models are winning on cost per task, not just benchmarks. step 5 preview ranks top-3 among…
open models are winning on cost per task, not just benchmarks. step 5 preview ranks top-3 among open models on the artificial analysis index while running at about an eighth of claude opus 5's per-task price, and its weights go public october 15.
the budget model is becoming the default.
Context
StepFun's Step 5 Preview page says the model is available through its products and API and will be released with open weights on 15 October. StepFun and Artificial Analysis both give it 44 on the Artificial Analysis Intelligence Index; Artificial Analysis labels it proprietary, released September 2026, 40th of 224 at the snapshot, at 0.72 dollars per index task (1.00 dollar input and 2.70 dollars output per million tokens). A search snippet of the Artificial Analysis Claude Opus 5 page shows 5.86 dollars per task.
The October 15 release is a plan and not a release. Top three among open models is not shown in the text read, and Artificial Analysis currently lists it as proprietary. About an eighth is plausible but not source-stated: 0.72 against 5.86 gives about 0.12 by simple arithmetic, valid only if configurations match, and the Opus figure is from a snippet. Vendor figures are not independent, and cost per task is on one index only.
Watch next
- The October 15 weights release and any Artificial Analysis reclassification.
Sources
- Step 5 Preview (StepFun)stepfun.com
- Step 5 (Artificial Analysis)artificialanalysis.ai
- Claude Opus 5 (Artificial Analysis)artificialanalysis.ai
Provenance
The note above is reproduced unedited from the original post, first published on Threads on 20 September 2026 at 21:07 IST. Sources are the papers and datasets the note draws on.
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