June 8 (Reuters) - ChatGPT creator OpenAI has confidentially submitted paperwork for a U.S. initial public offering, the company confirmed on Monday, aligning with rival Anthropic in moving toward the public markets as investors look for greater access to the artificial intelligence surge.

OpenAI did not reveal the size or pricing details of the proposed offering and said no specific timeline has been set. “It may take some time because certain initiatives are easier to pursue as a private company,” the firm said in a statement.

Reuters previously reported that the AI leader is aiming for a valuation of as much as $1 trillion in a market debut that could occur as soon as September.

At that level, OpenAI would join a potential wave of companies reaching trillion-dollar valuations in quick succession, marking what many see as the most significant test of investor demand for high-growth technology stocks in the past decade.

Elon Musk’s SpaceX was first to move, filing for an IPO that could become the largest ever if completed, with plans for a $75 billion offering at a $1.75 trillion valuation.

Anthropic, known for its widely adopted coding assistant Claude Code, announced on June 1 that it had confidentially filed for a U.S. IPO, just weeks after securing $65 billion in funding that valued the company at $965 billion.

“OpenAI appears to be preserving flexibility as Anthropic moved ahead following its massive funding round,” said Michael Ashley Schulman, partner at Cerity Partners.

On prediction markets, where participants place bets on future developments, most traders had expected OpenAI to submit IPO paperwork before Anthropic.

The anticipated IPOs of Anthropic and OpenAI represent a defining moment for the technology sector and global capital markets, as artificial intelligence cements its position as the decade’s dominant investment narrative.

Earlier this year, OpenAI disclosed that it was raising $110 billion at an $840 billion valuation, backed by major investors including SoftBank, Amazon, and Nvidia.

At that time, the company said ChatGPT had surpassed 900 million weekly active users and attracted more than 50 million paying subscribers.

The IPO filing comes after OpenAI reworked its partnership with Microsoft, one of its earliest supporters, enabling the AI company to establish new collaborations with firms such as Amazon and Google.

Microsoft’s cumulative $13 billion investment since 2019 played a central role in accelerating OpenAI’s expansion and fueled growth within Microsoft’s Azure cloud division.

In March, OpenAI reported $2 billion in monthly revenue and said it was expanding at roughly four times the pace once achieved by internet and mobile pioneers like Alphabet and Meta.

That figure compares with approximately $1 billion in quarterly revenue recorded at the end of 2024.

During its latest fundraising round, OpenAI informed investors that it does not anticipate reaching profitability until 2030, according to a person familiar with the discussions.

Still, the field it helped create has rapidly grown more competitive, prompting investors to question whether the AI sector’s explosive growth can continue at the same pace.

Anthropic has emerged as a leading competitor, driven by strong demand for its Claude AI among software developers for programming tasks, with some companies deploying its advanced Mythos model to identify weaknesses in their code.

While these large-scale offerings could energize the U.S. IPO market, some bankers caution that they may absorb capital that might otherwise support smaller listings.

“OpenAI does not want public market liquidity to be drained,” said Gil Luria, managing director at D.A. Davidson. “SpaceX and Anthropic are already ahead in the IPO queue, and established public rivals could also raise tens of billions through secondary offerings.”

SpaceX is expected to debut on the public markets this week.

OpenAI was established in 2015 as a nonprofit research organization but introduced a for-profit subsidiary four years later to finance the substantial costs of developing advanced AI systems.

Its hybrid governance model, which granted the nonprofit oversight of the for-profit arm, drew intense attention in late 2023 when CEO Sam Altman was briefly removed before being reinstated days later following internal backlash.

In December 2024, OpenAI announced plans to restructure as a public benefit corporation, saying the change would allow it to secure significantly more funding while loosening constraints tied to its nonprofit parent.

The restructuring sparked controversy after criticism from early backer Elon Musk, who later filed a lawsuit alleging that Altman and other executives had shifted the nonprofit’s mission toward private gain.

In May, a U.S. jury ruled against Musk, determining that OpenAI was not liable for claims that it had deviated from its original mission to serve humanity.

The unanimous decision removed a major legal uncertainty ahead of the IPO, with analysts noting that it cleared a significant obstacle for the company’s public debut.