Which frontier model for hard finance questions?
20 stock-market tax questions at four levels of difficulty, each asked with the cited law in the prompt and without it, so 40 in all. Claude Sonnet, Claude Fable, GPT-6 Astra and Grok 4.7, each at high effort. Claude Opus was not in these runs.
Right answers, of 40
Reply tokens, all 40 questions
What we would recommend. Start with the model that uses the fewest tokens, after checking each vendor's price per token, and run a larger question set before settling. The widest gap in right answers is Grok over GPT-6 Astra, where 4 questions went one way and none the other, with an exact McNemar p of 0.125. So 40 questions do not separate these models. The tokens differ by about 37 times, and the median question took 8.6 seconds on GPT-6 Astra against 124.7 on Grok.
Run through each vendor's own command-line tool, with X search on for Grok, on 31 Oct 2026, and on 4 Nov 2026 for Claude Fable. Five of the 40 prompts gained cited rules between the two dates. Tokens are as each tool reported them.