Claude Overtakes ChatGPT in U.S. Business Adoption for the First Time — Ramp's May 2026 AI Index, drawn from $100B+ in annual spend across 50,000 businesses, shows Anthropic at 34.4% business adoption versus OpenAI at 32.3% — the first time Claude has led. The engine is Claude Code, which has been growing 80× per year and now accounts for an estimated $2.5B run-rate revenue.