The Enterprise AI Power Shift: Anthropic Takes 40% of LLM Spend While OpenAI Falls to 27% — And Both Are Racing to IPO

Anthropic now captures 40% of enterprise LLM API spend, up from 12% in 2023. OpenAI has fallen to 27%, down from 50%. Ramp data shows Anthropic taking 73% of new enterprise AI purchases. Claude Opus 4.6 holds the #1 position across all three LMSYS Chatbot Arena leaderboards — the first model to do so. Anthropic's annualized revenue has reached $30 billion, surpassing OpenAI for the first time. Both companies are racing toward IPOs in late 2026: Anthropic targeting $60 billion at a $380 billion valuation, OpenAI at $852 billion. This analysis covers the market data, what's driving the shift, the benchmark dominance, the IPO dynamics, and what we still don't know.