The enterprise AI market is experiencing a seismic shift. Ramp’s April 2026 AI Index shows Anthropic at 30.6% enterprise adoption — a 6.3-percentage-point surge that is the largest monthly gain on record. OpenAI still leads at 35.2%, but the gap has narrowed from 11 points in February to just 4.6 points. At the current pace, Anthropic will overtake OpenAI within two months.
The Numbers That Matter
The Ramp AI Index tracks real corporate spend across tens of thousands of businesses using Ramp cards and invoicing. April’s data paints a clear picture of momentum shifting:
- Anthropic: 30.6% of businesses (up from 24.4% in March) — a 6.3-point monthly gain
- OpenAI: 35.2% of businesses — posted its largest single-month adoption decline
- Overall AI adoption: Crossed 50% for the first time in March, reaching 50.4% of businesses, up from 35% a year ago
One in four companies on Ramp now pay for Claude. A year ago, it was one in 25.
How Businesses Learned to Stop Worrying and Love Anthropic
Perhaps the most striking signal: Anthropic’s surge continued even after the US Defense Department designated the company a security risk in March. A judge has temporarily blocked the designation, and reports suggest the Pentagon will let some teams use Anthropic anyway. But the market response was unambiguous — businesses shrugged it off.
Anthropic now leads in three of the highest-adoption sectors:
- Software/Information: Anthropic 63% vs. OpenAI 54%
- Finance: Anthropic 52% vs. OpenAI 46%
- Professional Services: Anthropic 47% vs. OpenAI 44%
OpenAI still leads in every other sector, but Ramp economist Ara Kharazian doesn’t think that lasts: “The pattern in our data is consistent — what early adopters do today, the broader market does a few months later. The early adopters are picking Anthropic.”
The VC Effect: Who Adopts AI First
The Ramp data reveals an unexpected predictor of AI adoption: not industry, not company size, not location — it is funding source.
- VC-backed companies: 80% AI adoption rate
- PE-backed companies: 64%
- Everyone else: 45%
The effect holds across every industry. VC-backed construction firms adopt AI at 77%. VC-backed food companies at 67%. Both well above sector averages.
Kharazian explains: VCs function as a transmission mechanism for AI adoption — through portfolio-wide deals, top-down directives, and the cultural expectation that portfolio companies use the latest tools. What VC in 2026 is going to fund a founder who isn’t using AI?
Among VC-backed firms specifically, Anthropic (66%) already leads OpenAI (59%). The early adopters have made their choice.
Why This Matters
Enterprise AI preferences are not just vendor selection — they signal what capabilities businesses value most. Anthropic’s surge suggests companies are prioritising safety, reasoning depth, and reliability over raw model availability and brand recognition.
For the AI industry, this is a realignment. OpenAI has been the enterprise default since ChatGPT launched. That default is now contested. For businesses, the choice between OpenAI and Anthropic is becoming a question of what kind of AI strategy you want: breadth of model options or depth of reasoning capability.
The next two months will tell whether Anthropic’s momentum is a surge or a new equilibrium. Either way, the era of OpenAI’s unchallenged enterprise dominance is over.
SOURCES
- Ramp Economics Lab — April 2026 AI Index
- Ramp Vendor Data — Anthropic Adoption (April 2026)
