Fable 5's slow adoption suggests corporate willingness to pay for frontier AI has hit a ceiling
Anthropic's Fable 5 is considered the most capable AI model on the market. But new sales data shows U.S. companies are barely adopting it.
Spending data from financial services provider Ramp shows that companies are barely buying Anthropic's most powerful model through its API. In its first month after launch, Fable 5 accounted for only about six percent of the tokens purchased from Anthropic. Measured against total spending on Anthropic models, that number sat at 11.4 percent.
OpenAI's flagship model, GPT-5.6 Sol, captures 25 percent of tokens and 23 percent of spending at OpenAI. Overall, according to Ramp, Fable 5 brought in only about 75 percent of the model-related revenue that GPT-5.6 Sol generated, despite costing significantly more per token.
Ramp notes that the sample for the Fable data comes from the company's proprietary token spend management product and skews slightly toward tech companies. Actual Fable adoption is likely even lower than these estimates, assuming Fable 5 is used mainly for coding.
Price may be hitting a ceiling for corporate AI spending
Ramp economist Ara Kharazian attributes Fable 5's slow uptake to its price. The model costs about $10 per million input tokens and $50 per million output tokens, making it roughly twice as expensive as GPT-5.6 Sol or other Anthropic flagship models. Kharazian sees this as a new ceiling on what companies are willing to spend on AI, arguing that the extra performance simply isn't worth the cost.
It's likely more complicated. The performance edge Fable 5 offers may not matter for many use cases, or it's barely measurable in daily work. This points to a basic problem with calculating AI return on investment. How does a company put a number on the value an AI model delivers, especially when trying to measure the gap between one model generation and the next? It's a complicated and messy equation.
But the data doesn't say that a Fable 5 class model represents the upper limit of what companies would pay for AI per se. Models that are dramatically more capable could also deliver dramatically higher and, more importantly, tangible value. Companies will buy what pays off. But as long as that value stays abstract, their willingness to pay appears to be limited.
Growth at OpenAI and Anthropic is decelerating
According to Ramp, 43.5 percent of U.S. companies paid for Anthropic subscriptions or tokens in July, up 1.1 percentage points from the previous month. OpenAI reached 39.7 percent but grew by only 0.23 percentage points, lagging overall AI adoption growth. xAI posted its fastest growth since July 2025, rising 0.94 percentage points to 4 percent.
New customers keep signing up with American model providers, but advanced users, whose growing spending OpenAI and Anthropic increasingly depend on, are shifting toward open-source models. Ramp's data shows those models now trail frontier models by only a few months, and as a result, growth at the two leading AI labs is slowing.
Despite the skepticism around paying top dollar for premium models, total AI spending keeps rising. In July, the top 1 percent of U.S. companies spent a median of $7,400 per employee on AI. For the top 10 percent, that figure was $650, while the median company spent $11.95 per employee.
Ramp's data suggests companies are spending more on AI, but not without limits. Willingness to pay sharply higher prices for performance gains that are difficult to measure in daily work appears to have plateaued, at least if Fable 5 is any indication. According to Ramp, these are worrying signs for the AI industry, whose investment thesis depends on fast-growing revenue from increasingly powerful models.
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