OpenAI and Anthropic Battle for Business AI Market Share

OpenAI is currently growing its base of paying business customers faster than rival Anthropic in the third quarter of 2026, signaling a potential shift in the competitive landscape for enterprise artificial intelligence [1]. While Anthropic maintains a lead in total market share among the 70,000 U.S. businesses tracked by expense management firm Ramp, the volatility in adoption suggests that corporate AI spending remains highly sensitive to the release of new models [3].

The Shift in Enterprise Adoption

Anthropic first overtook OpenAI in May 2026, capturing 41% of the market compared to OpenAI’s 39% [1]. By July, Anthropic’s lead had widened to approximately 44% against OpenAI’s 40% [1]. However, recent data from the current quarter indicates that OpenAI has begun to regain momentum, adding new business users at a faster rate than its competitor [3].

Ramp economist Ara Kharazian attributes this recent growth to the performance of OpenAI’s GPT-5.6 Sol model, which is increasingly favored by developers [1]. In contrast, Anthropic’s Fable 5 model has faced headwinds regarding adoption and practical application, with some users expressing concern over its pricing and mandatory 30-day data retention requirements [3]. Despite these fluctuations, the broader market for AI services continues to expand; the percentage of companies paying for at least one AI service rose from 50% in March to nearly 56% by July [3].

Competitive Stakes and IPO Timelines

The competition for enterprise dominance occurs as both companies prepare for public market debuts. OpenAI confidentially filed for a U.S. initial public offering in June, following a similar move by Anthropic [2]. Investors are closely watching these filings, as they represent a significant test of public appetite for high-growth AI firms [2].

OpenAI, which reported $2 billion in monthly revenue as of March, is currently navigating the transition from a research-focused nonprofit to a public benefit corporation [2]. While the company’s valuation has been estimated at up to $1 trillion, it has indicated it does not expect to reach profitability until 2030 [2]. Anthropic, meanwhile, recently secured a $65 billion funding round that valued the company at $965 billion [2].

What to watch

• Quarterly Results: Monitor the final performance metrics for Q3 2026 to see if OpenAI’s current growth rate is sufficient to close the 3.8 percentage point gap in market share [3].
• IPO Progress: Watch for official disclosures regarding the size and timing of the respective IPOs, which will provide the first public look at the companies' actual financial health [1].
• Model Iterations: Observe whether Anthropic adjusts its data retention or pricing policies for the Fable model to address the user friction that has hampered its recent adoption [1].

The rapid switching between providers suggests that enterprise AI loyalty is currently low, with businesses willing to pivot whenever a new model offers a perceived advantage. Whether this volatility persists or stabilizes will be a defining factor for both companies as they move toward the public markets.