Markets adopt new playbook for mega-share debuts from SpaceX to Anthropic

Anthropic's upcoming IPO next week will see its early share price driven by forced index-fund buying rather than organic demand, mirroring SpaceX's June debut. The AI firm aims to raise up to $64.4 billion, valuing it at $1.4 trillion. Anthropic will be added to at least six major indexes within 5 to 15 days of listing, with passive demand estimated at 28% of shares offered, or roughly $19 billion. Index-rebalancing funds and hedge funds are expected to bid early to pre-position for this demand, similar to SpaceX's pattern. SpaceX shares rose 50% by day three after index inclusion and retail allocation of a fifth of its offering. Anthropic is also earmarking shares for retail investors, though its trajectory may differ as employees can sell some shares on day one and $26 billion in private sales lack lock-up restrictions.