Anthropic has issued a public warning to investors amid surging demand for artificial intelligence stocks, cautioning that several private and secondary market platforms are not authorised to facilitate transactions in its shares.

In an update published on its website this week, the AI company said a number of investment platforms offering access to its shares are doing so without its approval.

Anthropic specifically named Open Doors Partners, Unicorns Exchange, Pachamama Capital, Lionheart Ventures, Hiive (new offerings), Forge Global (new offerings), Sydecar and Upmarket as entities that are not authorised to provide access to buy or sell its stock.

“Any sale or transfer of Anthropic stock, or any interest in Anthropic stock, offered by these firms is void and will not be recognized on our books and records,” the company’s support page reads.

Anthropic’s notice comes amid a surge in investment platforms offering exposure to AI company shares, and their growth, through secondary markets, where existing investors sell stakes, as well as via tokenized securities, special purpose vehicles and other secondary holdings.

Anthropic, which is reportedly seeking fresh funding at a $900 billion valuation, has been particularly sought after