Anthropic’s flagship Fable 5 model is losing ground with enterprise customers as companies increasingly judge AI systems on price-to-performance rather than peak capability. Ramp data covering 70,000 U.S. companies showed Fable 5 accounted for about 11% of spending on Anthropic models more than two months after launch, little changed from 11.4% one month after release. The cheaper Opus 5 has already surpassed it in enterprise spending, while OpenAI’s GPT-5.6 captured 25% of enterprise token usage and 23% of spending during the same period. Open-source models also increased their token share to 62% by August, though they represented less than 4% of enterprise spending. The developments come as Anthropic prepares for a potential IPO and reports rapid growth, including 6,000 customers spending more than $100,000 annually and its first adjusted operating profit in the second quarter. Reported annualized revenue figures differ between accounts, with the latest report citing $65 billion in July and $47 billion in May, compared with earlier figures of $6.5 billion and $4.7 billion.