Anthropic vs OpenAI - higher valuation on December 31?

Prediction markets put the probability at 94%: Anthropic vs OpenAI - higher valuation on December 31. Currently, markets see this as likely (94% YES). The filing lands in the middle of what is shaping up to be a historic year for mega-cap debuts.

What’s Happening

The race for the title of the world's most valuable private AI company has shifted decisively in recent months, with Anthropic surpassing OpenAI in private-market valuation. On May 28, 2026, Anthropic closed a $65 billion Series H financing round at a $965 billion post-money valuation, a figure that moved the Claude developer ahead of its rival for the first time. The funding round was followed on June 4, 2026 by Anthropic's confidential IPO filing, carrying that same approximate $960 billion mark into its S-1 paperwork. This sequence of events has reset the baseline for the "anthropic vs openai - higher valuation on december 31" question, as the private-market marks now serve as the reference points for any year-end comparison [Yellow.com, Jul 04].

OpenAI has responded with its own capital markets strategy, though from a lower starting point. On June 9, 2026, OpenAI confidentially filed for its own IPO, with reports indicating a target valuation of $850 billion or more. That filing came roughly a week after Anthropic's, and the gap between the two private valuations is now approximately $115 billion. The IPO filings themselves have become a key variable in the "anthropic vs openai - higher valuation on december 31" market, as a public listing would shift the metric from private marks to a traded market capitalization. Polymarket traders currently assign a 68.5% probability to an OpenAI IPO by December 31, 2026, while the distribution for its closing market cap shows a 46.15% chance of debuting above $1.5 trillion [24/7 Wall St., Jun 09].

The competitive dynamics extend beyond the two primary firms, with SpaceX having completed its merger with xAI and set to begin trading within days, adding another mega-cap debut to the 2026 calendar. For the specific "anthropic vs openai - higher valuation on december 31" market, the key uncertainty is whether either company actually lists before year-end. If OpenAI goes public at a premium to its last private mark, the traded market cap could easily exceed Anthropic's $965 billion private figure. Conversely, if both remain private, Anthropic's current lead appears durable. As of July 7, 2026, prediction market pricing reflects a materially higher chance of an Anthropic IPO in the next six months than an OpenAI listing, a dynamic that could force a re-rating of both companies' year-end valuations [24/7 Wall St., Jul 07].

Traded on Polymarket — $51K Volume

Lower-volume market on Polymarket ($51K). Wider spreads expected — enter with limit orders and be aware of slippage risk. Currently 94c YES.