# Mercury vs Brex: which do AI models recommend for business banking, September 2026

Finance AI Recommendation Index, September 2026 Edition, Business banking. One of twelve models named Mercury first on the direct prompt; two named Brex. Page: https://finance-ai-index.com/treasury/business-banking/mercury-vs-brex/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| Mercury | 20% | #1 of 13 | 7% | 43 | 12 of 12 |
| Brex | 8% | #5 of 13 | 8% | 24 | 12 of 12 |

## The direct prompt, model by model

- Kimi K2: mercury first (first choices: Chase Business Banking, Mercury) (alternatives: Brex, First Internet Bank)
- Claude Haiku 4.5: brex first (first choices: Brex) (alternatives: Airwallex, Chase Business Banking, U.S. Bank)
- DeepSeek V4 Flash: brex first (first choices: Brex) (alternatives: Bank of America, Chase Business Banking, HSBC, Mercury, Relay, U.S. Bank, Wells Fargo)
- Gemini 3.5 Flash: neither first, one named (first choices: Rho) (alternatives: Bank of America, Brex, Chase Business Banking, Fifth Third Bank, Mercury, PNC Bank)
- Perplexity Sonar: neither first, one named (first choices: Rho) (alternatives: Bluevine, Brex, Relay)
- Grok 4.1 Fast: neither first, one named (first choices: Bank of America, Chase Business Banking) (alternatives: Brex, PNC Bank, Rho)
- MiniMax M2.5: neither first, one named (first choices: Chase Business Banking) (alternatives: Airwallex, Bank of America, Barclays, HSBC, Mercury, NatWest, Rho, Silicon Valley Bank, Wells Fargo)
- GPT-5.4 mini: neither named (first choices: Chase Business Banking) (alternatives: Bank of America, TD Bank, U.S. Bank)
- Mistral Small: neither named (first choices: Axos Bank, PNC Bank) (alternatives: First Internet Bank, Revolut Business, Wise Business)
- Llama 4 Maverick: neither named
- Qwen 3.7 Flash: neither named (first choices: Bluevine) (alternatives: Airwallex, Chase Business Banking, Relay)
- GLM 4.7 FlashX: neither named (first choices: Chase Business Banking) (alternatives: Airwallex, Qonto, Wise Business)

## What the models said about Mercury

- "Frequent account freezes/closure, slow support, funds held 60+ days | 15.4 negative reviews/month (4x industry average)" (DeepSeek V4 Flash, negative prompt, hard negative)
- "neobanks (such as Mercury, Bluevine, or Novo) rely heavily on automated fraud-detection algorithms" (Gemini 3.5 Flash, negative prompt, soft negative)
- "does not support physical branches or cash deposits" (Perplexity Sonar, budget prompt, soft negative)
- "I'd usually recommend Mercury if your priority is a modern, startup-friendly banking platform" (GPT-5.4 mini, paraphrase prompt, first choice)
- "For most mid-market B2B companies today, Mercury or Chase are the safest starting points" (Kimi K2, direct prompt, first choice)
- "Mercury, which is considered the best overall digital business banking platform for startups" (Llama 4 Maverick, paraphrase prompt, first choice)

## What the models said about Brex

- "Brex abruptly decided to stop servicing traditional small businesses, giving tens of thousands ... just 60 days to move their funds" (Gemini 3.5 Flash, negative prompt, hard negative)
- "Brex is best if you run a mid-market company and want a corporate card plus treasury and vault services in one platform." (Claude Haiku 4.5, direct prompt, first choice)
- "Brex offers both banking and corporate card services designed for venture-backed startups and mid-market companies" (Claude Haiku 4.5, paraphrase prompt, first choice)

Share is the count of first choices across the direct, paraphrase, budget and scale prompts over all twelve models, for a mid-market B2B company; rank is within the category. Comparisons are drawn for the top eight products in each category. Published under CC BY 4.0; the output is the models' output, and nothing here is a recommendation by the index.