SpaceX's completed June 2026 IPO at roughly $1.77 trillion underpins the 77.8% implied probability it will hold the higher IPO market cap versus OpenAI. Trader consensus reflects SpaceX's realized public valuation—now trading near $2 trillion amid Starlink growth and AI infrastructure contracts—against OpenAI's private status at an $852 billion March 2026 mark, with only preliminary talks around $1.4 trillion. Sam Altman's September confirmation of a 2027 IPO timeline, driven by AI safety priorities, further widens the gap. Key near-term catalysts include SpaceX's October 20 earnings, which could highlight AI compute revenue, and any OpenAI pre-IPO funding updates that might narrow but not close the valuation differential before OpenAI lists.