OpenAI Eyes 2027 IPO Delay As Washington Clears Anthropic's Mythos 5

Washington regulators approved Anthropic's Mythos 5 while slowing OpenAI's GPT-5.6 rollout, creating an unprecedented regulatory split in the AI industry. OpenAI has postponed its initial public offering (IPO) to 2027, according to sources familiar with the matter, as the U.S. government cleared Anthropic's next-generation model Mythos 5 for deployment but held its Fable 5 offline and phased the launch of OpenAI's GPT-5.6. The simultaneous moves reshape the competitive landscape for two of the world's most valuable AI startups, each reportedly targeting a $1 trillion valuation at IPO.

OpenAI, the creator of ChatGPT, has been under mounting pressure to transition from a capped-profit structure to a for-profit corporation — a prerequisite for any public listing. The company's board had initially signaled a 2025–2026 IPO window, but regulatory uncertainty around its flagship GPT-5.6 model, combined with internal governance debates, pushed the timeline to 2027. Anthropic, founded by former OpenAI employees, has taken a different path, winning Washington's approval for its Mythos 5 model while its sibling Fable 5 remains grounded pending further safety reviews.

The divergence stems from the Biden administration's evolving AI regulatory framework, which evaluates models on a case‑by‑case basis. Anthropic's Mythos 5 passed safety tests conducted by the National Institute of Standards and Technology (NIST) and the AI Safety Institute, while OpenAI's GPT-5.6 was flagged for potential misuse in generating disinformation and automating cyberattacks. The White House's phased rollout order means GPT-5.6 will be released in incremental capability steps over 18 months, a condition OpenAI reluctantly accepted.

Both companies filed confidential IPO documents with the SEC earlier this year. OpenAI's delay to 2027 gives it time to restructure and comply with regulatory demands. Anthropic, meanwhile, expects to proceed with its IPO in late 2026, buoyed by the Mythos 5 approval. The combined market capitalization of the two firms could exceed $2 trillion, analysts estimate, making theirs the largest tech IPOs since Alibaba's 2014 debut.

Industry observers see Washington's split decision as a template for future AI regulation — rewarding safety-first development while penalizing perceived recklessness. "This is the first tangible signal that regulators are willing to pick winners and losers based on model behavior, not just promises," said Dr. Elena Voss, a senior fellow at the Center for AI Policy. The approach could force other AI labs to prioritize interpretability and red‑teaming over raw performance.

Looking ahead, OpenAI must navigate the phased GPT-5.6 launch while convincing investors its governance overhaul is complete. Anthropic must scale Mythos 5 commercially without running afoul of evolving rules. Both companies face a crowded IPO queue, with competitors like Cohere and Mistral also eyeing public listings. The next milestone comes in December 2026, when the AI Safety Institute publishes its updated evaluation framework — a document likely to determine which models get the green light and which trigger IPO delays.