Anthropic leads Polymarket odds at 54.8% for the largest 2026 IPO by market cap due to its targeted November listing, with investors projecting a $1.8–2 trillion valuation that would exceed SpaceX’s June debut. SpaceX, now at 41.5% implied probability, priced its record IPO at $1.77 trillion after completing the offering in June at $135 per share, though post-listing trading and lockup releases have tempered momentum. xAI’s 25.5% reflects its February all-stock merger into SpaceX at roughly $250 billion embedded value, folding its assets into the public entity rather than supporting a standalone debut. Lower-probability names such as OpenAI and ByteDance show negligible near-term catalysts or confirmed timelines capable of challenging these valuations, leaving trader consensus anchored on Anthropic’s execution and SpaceX’s established scale.