Now that Anthropic’s S-1 is public, it provides a natural comparison point to its rival OpenAI, if and when the latter eventually files its IPO prospectus (likely sometime in 2027).
Analysts have been poring over Anthropic’s filing this week, and so far are already expecting OpenAI’s version to tell a different financial story. Specifically, it could have two potential advantages over Anthropic. The first is in the revenue growth rate. Second, is the diversity of the business, specifically OpenAI’s consumer business.
Anthropic’s revenue growth slows as OpenAI picks up speed. But what about margins?
In the first six months of 2026, Anthropic’s revenue hit $16.3 billion, a 1,300% year-over-year increase—just five years after its founding in 2021. That’s the fastest growth rate among multiple other eye-popping growth rates the company has seen in recent years. In 2023, Anthropic’s revenue was $41 million, and in 2024 it grew 841% to $386 million. in 2025, its revenue jumped again to $4.6 billion, up 1,088%.
“A company hitting this kind of scale this quickly is unprecedented,” Aman Verjee, General Partner and Founder of Practical Venture Capital, told Fortune. Others we spoke to called it “stunning” and “extraordinary.” The consensus is the growth rate is potentially historic.
But investors—and Anthropic itself—don’t expect the trend to continue. “We do not expect our revenue will continue to grow at comparable rates, and we cannot assure you that it will continue to grow at all,” Anthropic’s S-1 reads. The company attributes its ultra-fast growth rate to “early-stage adoption dynamics, the nascency of the AI market, and rapid initial customer expansion,” and notes that it “may not be sustainable over time, and may decline significantly and more rapidly than we anticipate” as the market matures.
We’re already seeing evidence of that slowing. Although the S-1 does not include Anthropic’s third-quarter results, it mentions that revenue was 86-times its Q4 2024 revenue—a sneaky detail spotted by Fortune‘s AI editor Jeremy Kahn. Since Q4 2024 revenue was $197 million, that implies its Q3 2026 revenue was roughly $16.9 billion. That’s a 47% quarter-on-quarter increase from Q2 to Q3, a sharp drop from its 132% increase between the fourth quarter of 2025 and Q1 2026, and then a 144% increase between Q1 and Q2 2026.
OpenAI’s revenue growth, meanwhile, seems to be picking up steam (from what we can surmise from leaks and executive comments), and sources are expecting its S-1 will reveal accelerating growth on the top line. In August, its CFO Sarah Friar told investors the company now makes more money on enterprise customers than consumers, CNBC reported. Perhaps more concerningly for Anthropic, software engineers are increasingly using OpenAI’s models after a series of price cuts have made them among the most affordable on the market, The Information reported this week.
Anthropic is not going down without a fight. Seemingly in response to OpenAI’s traction with developers, Anthropic has also been cutting costs and offering promotional discounts. Meanwhile, it’s signing up for billion-dollar compute deals that may not pay off, as Fortune‘s Jeremy Kahn and Sebastian Herrera reported. Is the AI business a race to the bottom, with thinning margins for both companies?
“Extraordinary revenue growth doesn’t necessarily trend into extra extraordinary investment returns,” Jonathan Tower, the Founder and Managing Partner of the venture firm Catapult, told Fortune. “My broader concern is that investors are confusing the magnitude of the AI opportunity with the profitability of its participants. AI could become the most consequential technology of our lifetime and still produce some of the most spectacular investment losses of our generation.”
Once considered a weakness, OpenAI’s consumer business could prove a major strength
Ironically, even though OpenAI has been racing to catch up to Anthropic’s enterprise business for the bulk of this year, the investors we spoke to believe its consumer business could prove a hidden strength.
OpenAI has a “strong consumer brand and presence,” Verjee said. That’s an “advantage” that could translate into higher margins, Tower added.
One consumer-centric revenue stream OpenAI has also been working hard to increase is its advertising platform. This month it reported it has 100,000 advertisers signed up to serve ads in ChatGPT. This week, it debuted another ad format, featuring multiple images, as it continues to evolve its offerings.
Another unique, consumer-facing advantage for OpenAI could be its forthcoming family of hardware devices, crafted by the legendary iPhone designer Jony Ive. OpenAI has promised to disclose more details by the end of the year. These devices could extend consumers’ relationships with ChatGPT into the physical world, entrenching them in an Apple-like ecosystem of AI assistants.
Anthropic knows its consumer business is a weakness, and potentially a blind spot its competitors could exploit to get ahead. The S-1 references unnamed competitors with “stronger consumer-facing businesses, larger consumer user bases, more established brands, broader distribution, or deeper customer relationships.” Those companies could leverage those relationships to build their enterprise businesses, in order to “compete more effectively with us,” Anthropic says.
Yet Anthropic doesn’t plan to go toe-to-toe with its competitors in the consumer business, which it says “would require significant time and resources beyond our current plans.”
“The timing of the IPO benefits Anthropic by allowing it to raise the most, the earliest, and to benefit from persistent equity market enthusiasm,” James Gellert, Executive Chairman at the financial intelligence company RapidRatings told Fortune. The success of Anthropic’s public offering could be among the biggest factors in OpenAI’s future success—for better or worse.
This story was originally featured on Fortune.com
