Largest IPO by market cap in 2026?

What this question means

A two-horse race. Anthropic at 59% and SpaceX at 38% take nearly all the probability for the largest IPO by market cap in 2026, with OpenAI at 1% and the rest of a twelve-name field — ByteDance, Stripe, Databricks, SHEIN, Waymo — at zero.

The structure here is compound in a way that is easy to miss. Winning requires two things: listing at all during 2026, and listing at a larger valuation than any other company that also lists. A company could go public at an enormous valuation and still lose this question to a larger one in the same year.

That interaction is why the field collapses to two names. Only a handful of private companies are plausibly large enough to lead a year, so the question is less about the whole market than about which of a very short list moves first.

Read alongside the individual IPO questions on this board — where the same names carry very different standalone odds — the picture becomes clearer.