OpenAI has regained over 40% of the U.S. enterprise AI market share, surpassing Anthropic, according to data from Ramp, a corporate credit card and expense management platform. In May OpenAI held a 39% share while Anthropic had 41%, with Anthropic’s share rising to nearly 44% by July and OpenAI’s falling to around 40%. Since the third quarter, OpenAI’s growth rate has been faster than Anthropic’s. The data covers spending by over 70,000 U.S. technology industry companies using Ramp’s services, though it does not represent the full market as large firms use other expense management tools. Ara Kharazian of Ramp notes GPT-5.6Sol is gaining developer favor due to its strong performance, while Anthropic’s Fable product faces issues with pricing and data retention requirements (formerly requiring 30 days of data storage, which caused controversy). The paid penetration rate of enterprise AI rose from over 50% in March to nearly 56% in July, indicating ongoing market expansion despite vendor competition. Customer loyalty among AI companies remains highly volatile as firms continue to choose between OpenAI and Anthropic based on new model developments.