For the first time, more US businesses are paying for Anthropic's Claude than for OpenAI's ChatGPT, according to the May release of the Ramp AI Index. Anthropic's paid business adoption climbed 3.8 points to 34.4% of businesses in April while OpenAI fell 2.9 points to 32.3%, marking a clean crossover in the enterprise AI race that OpenAI has led since ChatGPT launched.
Quadrupling In A Year
The Ramp AI Index is built from corporate-card and invoice spend across more than 50,000 US businesses on Ramp's spend-management platform. Ramp lead economist Ara Kharazian writes that Anthropic has roughly quadrupled its business adoption in the past 12 months, while OpenAI's adoption grew only 0.3 percentage points. Overall AI adoption among the tracked cohort edged up 0.2 points to 50.6%, putting more than half of US businesses on at least one paid AI tool.
Kharazian credits Anthropic's surge in part to Claude Code, the fastest-growing product in the company's history, which has pulled engineering teams into Claude-based subscriptions and inflated paid-vendor counts in Ramp's data.
Three Headwinds For Anthropic's Lead
Ramp's note is unusually candid that the lead may be fragile. Kharazian flags three structural risks: token-based pricing creates an incentive misalignment that has already pushed customers like Uber over their AI budgets; recurring Claude outages and rate limits in April triggered widespread user complaints; and recent Claude model updates triple token cost for prompts that include images, compounding cost and compute pressure. Anthropic reset usage limits in April and locked in a new SpaceX-linked compute deal to ease constraints, but cost-sensitive teams are already migrating to cheaper open-source models on AI inference platforms — currently among the fastest-growing SaaS vendors on Ramp.
Reads For The AI IPO Window
The crossover lands in the same week that Anthropic confirmed a confidential S-1 filing for an IPO targeting a $3 trillion AI listing slot, and that SpaceX SPCX opened the AI IPO window with a 19% Nasdaq debut. A separate March 2026 IDC survey of more than 1,000 organisations found only 19% reported extensive use of Claude, with OpenAI and Google still ahead on depth-of-use within incumbent accounts. Read together, Ramp and IDC suggest Anthropic is winning new paid adoption while still building toward parity on per-organisation depth.
For S-1 readers, both signals matter. Anthropic's data-center commitments are sized for the optimistic adoption trajectory; the Ramp print is the cleanest live evidence yet that the trajectory is real, while the headwind list is the cleanest live evidence that it is not yet locked in.
Reporting based on coverage from Ramp Economics Lab, VentureBeat, TechWire Asia and The Information.