SpaceX's completed June 2026 IPO at a $1.77 trillion valuation and $75 billion raise established the current benchmark for largest 2026 debut, yet Anthropic's late-October S-1 filing—with first-half revenue surging to $16.3 billion—positions it to potentially exceed that scale at a targeted $1.5–2 trillion valuation and up to $100 billion raise ahead of its planned mid-November listing. Traders assign SpaceX a 57% implied probability of retaining the title versus Anthropic at 43%, reflecting capital-weighted consensus on whether Anthropic's revenue trajectory and AI market positioning can deliver a larger market cap at pricing. xAI's February acquisition by SpaceX removes it as a standalone contender, while other names remain below 1% odds amid limited filing progress.