he same urgency now extends to plans for their blockbuster IPOs. The companies are racing to beat one another to market, viewing a first listing as a way to frame how investors will value the companies and establish their CEO as the leading voice of AI. As recently as May, many advisers expected OpenAI would be the first to take the initial steps to go public. OpenAI has told some investors it was targeting an IPO as early as September, two people familiar with the matter said. But Anthropic jumped in first, announcing on June 1 that it had filed confidentially with US regulators. OpenAI followed on Monday, a week later. The stakes extend beyond the clash between Altman and Anthropic CEO Dario Amodei, a former OpenAI researcher who was one of the people responsible for the core technology that made ChatGPT possible. The competition is spilling into Wall Street. It’s rare for two such big direct rivals to raise capital at the same time, and the IPOs will be so big that they are by necessity turning to some of the same banks for help. OpenAI is looking to go public at a valuation around US$1 trillion, Reuters previously reported. Bankers and other advisers are navigating increasingly complex relationships with both OpenAI and Anthropic, three people familiar with the matter said. Executives at both companies have pressed their IPO advisers for insight into the rival’s plans, the people said, prompting some banks working with both companies to erect internal barriers between deal teams to prevent information leaks. All-out war Top bosses often clash. Elon Musk and Jeff Bezos have traded public barbs in their space race, and Bill Gates and Steve Jobs quarrelled over whether Microsoft products copied Apple’s. The tension between Altman and Amodei is the driving force in today’s biggest technological revolution – influencing how quickly AI tools are released, what features they include and, ultimately, how people interact with the technology in their daily lives. “It’s all-out war between these guys,” said Anastasios Angelopoulos, CEO of Arena, a top AI benchmarking and evaluation company. “Every time there’s a new release from Anthropic, the bet will be that OpenAI is soon to follow and vice versa.” Both companies declined to comment on the CEO rivalry. Fight over revenue recognition The companies are also at odds over how they tell their financial stories to investors. OpenAI has told investors and employees that Anthropic’s preferred accounting method overstates its revenue by billions of dollars, according to two people familiar with the matter. In April, OpenAI’s chief revenue officer, Denise Dresser, told employees that OpenAI considers Anthropic’s financials inflated, according to a company memo reviewed by Reuters. That’s because Anthropic recognises the full amount customers pay for its AI services as revenue, but later routes some of that to partners such as Amazon and Google. OpenAI uses a different method, reporting only net revenue after paying its partner, Microsoft. Anthropic told Reuters that it follows established accounting practices and recognises gross revenue because it is the “principal” in the transaction, while its cloud partners are distribution channels. Dresser’s internal communications aimed to reassure OpenAI staffers who have been demoralised by Anthropic’s rapid growth, two of the people Reuters spoke to said. “One reason for Anthropic to try to beat OpenAI out to the public market is that they will get to set the agenda for how a frontier model reports financials and do so in a way that is favourable to their financial model,” said Gil Luria, analyst at D. A. Davidson. The desire to best its rival has, at times, led to tensions within OpenAI. Altman recently clashed with Chief Financial Officer Sarah Friar over whether the company could meet the obligations required for a public listing on such a compressed timeline, three people familiar with the matter said. Altman told her to figure it out or hire different bankers and lawyers who could pull it off, they said. Friar has since told advisers that the company’s leadership is aligned on timing, another person said. In an interview on CNBC after Anthropic’s filing, Altman said he didn’t want to rush OpenAI’s debut. A long-running feud The rivalry dates back to late 2020, when Amodei left his job as OpenAI’s vice president of research, along with several others, to create Anthropic, which promised to prioritise safety. Many OpenAI employees saw the move as a rebuke of Altman’s approach. In early 2022, Anthropic trained the first version of its chatbot Claude, but held it back from public deployment to conduct safety research instead, Anthropic later said. OpenAI had similar projects underway. Some employees were working on a “super-assistant” tool powered by OpenAI’s then-advanced models, four people familiar with the matter said. Meanwhile, co-founder John Schulman was separately working on a chat interface. Schulman didn’t respond to a request for comment. At one point, OpenAI officials considered launching the chat-based assistant tool in March 2023, alongside the release of its GPT-4 large language model, the four people said. But rumours of Anthropic’s project in mid-November galvanised Altman. He directed OpenAI staffers to develop a chatbot that could be ready as quickly as possible. “All of a sudden, it was like, we got to ship this in two weeks,” one of the people said. The product, ChatGPT, was released on November 30, 2022. It quickly became the fastest-growing consumer application in history, drawing millions of users and upending tech giants’ previous product roadmaps. Anthropic, which launched its Claude chatbot a few months later, spent about three years catching up to OpenAI. Around late 2024, Amodei redirected researchers to focus on so-called reasoning models after seeing OpenAI’s early success in that area, three people familiar with the matter said. The dynamic flipped in late 2025 when Anthropic, which long focused on business customers, released a powerful update to its Claude Code tool. OpenAI, which generates much of its revenue from consumer subscriptions to ChatGPT, has now redoubled its focus on enterprise software and allocated more resources to its own coding product, Codex. Open distaste Relations between the two companies deteriorated after OpenAI’s board unexpectedly fired Altman in late 2023. As the board cast about for options, directors briefly spoke with Amodei about merging the two labs under his leadership. In a recent deposition, one former OpenAI executive said the idea was considered “extremely briefly” before the board moved on to other ideas. Even so, news of the proposal infuriated many OpenAI employees, three people familiar with the events said. Altman was reinstated within days, but that anger persisted. The feud is becoming increasingly public. In February, Altman slammed Anthropic’s Super Bowl ads as “deceptive” for misrepresenting OpenAI’s plans to sell ads on ChatGPT. In March, Amodei accused Altman of leveraging Anthropic’s dispute with the Pentagon to help OpenAI. At an AI summit in India in February, Prime Minister Narendra Modi encouraged all the tech executives on stage to join hands in a show of unity. In a moment captured in a viral video from the summit, Altman and Amodei, standing side by side, refused. Additional reporting by Milana Vinn, Kenrick Cai and Jeffrey Dastin. Editing by Sayantani Ghosh, Ken Li and Claudia Parsons. All courtesy of Reuters. Further reading: Why Walmart’s partnership with OpenAI is a retail game-changer