Anthropic PBC's initial public offering has attracted subscriptions for approximately six times the shares available, signaling intense investor demand for a deal that could become the largest stock offering in history. The Claude AI model developer and its co-founders plan to raise up to $64.4 billion through the IPO and an additional $26 billion via private placement, surpassing SpaceX's previous record as the biggest listing ever. Investment bankers have informed potential investors that Anthropic will prioritize existing backers, with some buyers expected to receive fewer shares than anticipated. Representatives for Anthropic have not commented on the subscription details, which remain subject to change as demand evolves.