Until OpenAI and Anthropic get close enough to their planned IPOs to disclose their financials, outside sources are the best window into how their businesses are performing. One such source, Ramp—the corporate credit card and expense management platform—has just shared some striking new figures: OpenAI has started closing the gap with Anthropic among U.S. businesses. OpenAI, once the clear front-runner with both businesses and consumers, lost its lead among Ramp’s paying business users back in May. That’s when Anthropic hit 41% market share compared to OpenAI’s 39%. The ChatGPT maker hasn’t regained that lead since. As of July, Anthropic holds nearly 44% while OpenAI sits at almost 40%.

The data spans more than 70,000 American businesses that funnel billions through Ramp’s bill pay and corporate card products. Ramp’s customer base cuts across industries, but given its status as a go-to Silicon Valley corporate card, it tilts heavily toward the tech sector. A deeper dive into the latest numbers, according to Ramp economist Ara Kharazian, shows that OpenAI is currently growing faster among this segment in Q3 to date than Anthropic. Of course, there’s still a month left in the quarter—and that’s roughly 30 AI years—so the trend could easily flip again before it wraps. Ramp also declined to share actual dollar figures, offering only percentages.

To borrow ChatGPT’s own hedging style for a moment: this isn’t a measure of the entire market. It excludes large enterprises that rely on spend-management tools from providers like American Express rather than Ramp. But it’s enough data to reveal market signals. And what it shows is that Anthropic hasn’t secured a permanent win. Businesses are open to switching back and forth as each lab rolls out new models—volatility that should give both companies’ investors pause about how “sticky” enterprise AI spending really is.

“GPT-5.6 Sol is really good, increasingly the choice for developers,” Kharazian posted on X about OpenAI’s renewed growth. “Fable 5, meanwhile, disappointed both in adoption and real-world application given price + data retention requirements imposed by regulators,” he added. That may be an oversimplification. Fable—Anthropic’s higher-end model tier—is pricey, but it’s also designed for a more specialized set of use cases than a general-purpose chatbot. Still, Anthropic did stir some backlash when it warned Fable users that it must retain their data for 30 days.

Ramp’s data also suggests that both companies should be growing business revenue, even as they battle for market share, because the overall market is expanding. The share of companies paying for AI among these Ramp customers has been steadily rising. It crossed 50% in March and reached nearly 56% by July.