AI Lab Private Valuations 2026

Neither OpenAI nor Anthropic is public, so there is no ticker—but Polymarket runs deep strike ladders on both companies' year-end 2026 valuations off NPM secondary-market marks, and they function as a live options chain on private AI.

The inversion has widened into a gap of roughly two to one. Anthropic's ladder has resolved through $1.0T and $1.1T and prices ↑$1.25T at 98%, ↑$2.0T at 65.5% and ↑$2.5T at 49.5%. OpenAI's prices ↑$1.0T at 59.5% and ↑$1.25T at 37%. Matched on probability rather than on strike, Anthropic's mark sits about twice OpenAI's: where OpenAI is a coin flip near $1.0T, Anthropic is a coin flip near $2.5T.

And the depth has moved with it. Anthropic's three deepest contracts of the day are its three highest strikes—$5.0T at 7.1% took $94,296, $4.0T at 11.1% took $65,158, $3.0T at 29.5% took $30,974—while the 92.5% rung at $1.5T took $1,113. OpenAI's entire ladder turned $2,360 against $210,898 of open interest.

The money is not trading the level. It is buying Anthropic's upside tail.

The two Polymarket December 31 strike ladders side by side. Read them as cumulative distributions: each row is the probability the company's mark touches that level at any point before year end, not where it finishes.

Anthropic's book carries $1.38M of open interest against OpenAI's $210,898—a six-to-one gap in standing positions on two companies that were, a year ago, routinely quoted within a turn of each other.

The inversion at a matched probability, priced directly. Anthropic ↑$2.0T at 65.5% against OpenAI ↑$1.0T at 59.5%—two contracts the market gives roughly the same chance, on marks a full trillion dollars apart.

This is the cleanest single expression of what the ladders say. It is not that Anthropic is expected to be worth more than OpenAI at some tail; it is that the median pricing has crossed, and the strike ladders let you read the crossing point rather than infer it.

Two spotlight binaries on OpenAI specifically. OpenAI $1T+ valuation in 2026 is a cleaner year-level question than the ladder rung above it, which resolves on any touch during the year—the gap between the two is the touch premium, and it is worth reading them side by side rather than treating either as the answer. OpenAI vs Meta asks which is worth more on December 31.

Both are OpenAI-side books. There is no Anthropic equivalent listed on either regulated venue, which is itself a note on how recently this repricing happened.

The IPO clocks, and they say something the valuation ladders do not. Kalshi prices Anthropic announcing an IPO before November 1 at 67.5% and before January 2027 at 85%. Its OpenAI equivalent prices an announcement before June 2027 at only 77.5%, before April 2027 at 61.5%. On announcement timing the market now expects Anthropic to move first, and Anthropic's ladder carries more open interest doing it—$719,546 against OpenAI's $513,593.

Polymarket asks the harder version—an actual IPO, not an announcement—and prices OpenAI IPO by December 31, 2026 at 20%, with $22,575 of the book's $23,572 on that single rung.

One reading trap before you use the OpenAI ladder. Its Before Jul 1, 2026 and Before Aug 1, 2026 rungs both show a 50% midpoint and together carry $195,013 of open interest—windows that closed weeks ago on a ladder that still displays them. Check rung status before reading the shape; this is the third book in this catalog today with the same artifact.

Manifold's independent read on the same two companies. The OpenAI book is a September 30 ceiling ladder—resolved through .8T, pricing ≥$1T at 64.7%, within five points of Polymarket's year-end $1.0T rung despite a three-month-shorter window. The Anthropic book is a full-year Categorical putting 68.9% on the $1.6–3.2 trillion bucket and 14.2% above $3.2T.

Both are play-money and effectively untraded—$16 and in twenty-four hours. Treat them as a sanity check on direction, not as prices. On direction they agree: Anthropic's central bucket sits above OpenAI's.

• The Anthropic–OpenAI inversion is now roughly two to one on matched probability. Anthropic is a coin flip at $2.5T; OpenAI is a coin flip at $1.0T. Both ladders are quoted off the same NPM marks, so this is not a methodology artifact.
• Anthropic's flow is entirely in the upside tail. $190,428 across the $3.0T, $4.0T and $5.0T rungs—every one priced under 30%—against $1,113 on the 92.5% rung. Whether that is conviction or cheap optionality, it is the same shape showing up in the Fed decision book, the BMW winner book and the midterms combo books today.
• Touch versus level. The Polymarket ladders resolve on any print reaching the strike; the standalone $1T binary resolves on the year-end mark. The gap between them is the touch premium and it is the most mispriceable thing on this page.
• The IPO clocks disagree with the valuation story's usual direction. The market expects Anthropic to announce first, and backs that with 40% more open interest than the OpenAI ladder carries.
• $195,013 sitting on two closed OpenAI IPO rungs. Windows that expired in July and August, still displaying 50% midpoints. Read rung by rung.
• What would break the inversion. A funding round at a headline number on either side, or an actual S-1. The ladders reprice on NPM marks, which move on transactions—so the next print, not the next news cycle, is the catalyst.