Anthropic has issued a public warning targeting a range of secondary market platforms and investment intermediaries that it says are not authorized to facilitate the buying or selling of its shares, as investor appetite for exposure to high-growth AI firms continues to intensify.
In an updated notice on its website, Anthropic named several firms—including Open Doors Partners, Unicorns Exchange, Pachamama Capital, Lionheart Ventures, Hiive (new offerings), Forge Global (new offerings), Sydecar, and Upmarket—as entities it claims are not permitted to provide access to its equity. The company stated that any attempted sale or transfer of its stock through these channels would be considered void and would not be recognized on its official records.
The warning reflects broader turbulence in private markets, where access to shares in high-profile AI companies has become increasingly competitive and complex. Secondary platforms, special purpose vehicles (SPVs), and tokenized investment products have expanded rapidly in recent years, offering investors indirect exposure to companies that are not publicly traded.
Some of the named platforms pushed back against the allegations. Forge Global said it was included in error and is working with Anthropic to resolve the issue, emphasizing that it does not facilitate private share transactions without company approval. Sydecar stated that it only provides administrative services and does not directly buy or sell securities, adding that it requires compliance attestations from sponsors regarding share transfer approvals.
Hiive also defended its practices, stating that it invests heavily in compliance and legal infrastructure and only processes share transfers approved by issuers, while acknowledging broader concerns about scams and unauthorized transactions in secondary markets.
The dispute comes as Anthropic is reportedly attracting intense investor demand, with secondary brokers describing its shares as extremely difficult to source. The company has also been rumored to be preparing a new funding round at a valuation as high as $900 billion, underscoring the extraordinary appetite for exposure to leading AI developers.
The rise of alternative investment structures has further complicated the landscape. Some crypto-linked firms, including exchanges like OKX, have introduced derivative products tied to private company valuations, offering exposure without actual ownership of shares. Meanwhile, SPVs allow investors to pool capital to indirectly hold stakes in private firms, though these structures can vary widely in legitimacy and authorization.
Anthropic emphasized that both its common and preferred stock are subject to strict transfer restrictions, meaning any sale not approved by its board is invalid. The company also stated that it does not permit SPVs or similar structures to acquire or market its shares, and that any offers to invest in its financing rounds through such mechanisms are prohibited, reinforcing its efforts to maintain tight control over its ownership structure amid rapidly expanding investor demand.
