OpenAI, Anthropic Confidentially File for IPOs; Race for 2026 Debuts at $1T+ Valuations

<cite index="64-2">OpenAI confidentially filed for an IPO with the SEC, setting the stage for what could be one of the largest public markets debuts in history, joining Anthropic which filed confidentially on June 1</cite>. <cite index="62-2">OpenAI is confidentially filing for an IPO targeting a September 2026 debut at a valuation of $730 billion to $850 billion, with both companies now headed toward simultaneous public listings</cite>. <cite index="63-2">SpaceX filed its S-1 IPO prospectus with the SEC in May 2026, and both Anthropic and OpenAI have now confidentially filed their own draft prospectuses, setting the stage for what could become the most consequential stretch of tech listings since the dot-com era</cite>.

<cite index="67-1,67-3">Anthropic's confidential S-1 filing started the SEC clock on June 1, and for a company of this scale, confidential review typically runs three to six months, putting a public S-1 release in roughly September 2026, an institutional roadshow through September and early October, and a first trade date targeting October</cite>. <cite index="67-2">OpenAI filed its own S-1 on June 8 but is now leaning toward 2027 according to Bloomberg, citing market volatility and CEO Sam Altman's hard floor of a $1 trillion listing price following SpaceX's stock retracement</cite>. <cite index="65-4">Anthropic's annualized revenue surged from $9 billion at the end of 2025 to over $44 billion by May 2026, with around 80% of revenue from enterprise customers and Anthropic's share of the enterprise AI market surpassing OpenAI's for the first time in April 2026</cite>.

<cite index="67-4">In a two-company race where both companies sell near-identical products to overlapping enterprise customers, the second company to go public does not get a clean valuation debate; it gets priced relative to the first</cite>. <cite index="67-5">OpenAI is priced at approximately 34x its current run-rate revenue versus Anthropic at approximately 20x, and by the time OpenAI lists in 2027, it will have multiple quarters of audited losses on record</cite>. <cite index="68-3">The three IPOs together could demand north of $200 billion from public markets, compared to the entire US IPO market raising just $45 billion in all of 2025</cite>. Architects evaluating enterprise AI platform lock-in should monitor which company prices first, as Anthropic's October debut could establish the public-market multiple for all frontier AI revenue going forward.