Anthropic warns investors against unauthorized share trading platforms

Anthropic has updated its website to explicitly warn investors that a list of private and secondary investment platforms are not authorized to offer access to its shares. The company named Open Doors Partners, Unicorns Exchange, Pachamama Capital, Lionheart Ventures, Hiive, Forge Global, Sydecar, and Upmarket as unauthorized entities. According to the Anthropic support page, “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,” as the company’s preferred and common stock are subject to transfer restrictions.

Several of the listed platforms pushed back against the warning. Forge Global claimed it was included in the alert erroneously and is working to remove its name. The platform stated that it does not facilitate transactions in any private company’s shares without explicit approval from the company, and on Tuesday added a warning to its own Anthropic page. Sydecar stated that it acts only in an administrative capacity, does not buy or sell securities, and requires sponsors to attest they have the necessary approvals. Unicorns Exchange also emphasized that it provides only introduction services, requiring buyers and sellers to perform their own due diligence. However, in light of the warning, Unicorns Exchange spokesperson Iris Harpaz described the company’s move as injustice [sic] allegations and stated that the platform has ceased marketing Anthropic-related opportunities.

The dispute highlights the demand for artificial intelligence equity. Iris Harpaz of Unicorns Exchange reported that the platform received more than 50 inquiries from institutional investors for Anthropic shares in the past three months, with aggregate demand that exceeded $1tr. This activity comes as Anthropic is rumored to be raising fresh funding at a $900 billion valuation, making its shares some of the most difficult to source on the secondary market—a marketplace where existing shares are traded.

Other market participants supported the AI company’s stance. Dakota Betts, a spokesperson for Hiive, stated that Anthropic is right to take concerns around unauthorized share sales and investment scams seriously, noting that Hiive requires issuer approval for all facilitated transfers. The broader secondary market has seen various structures, including Special Purpose Vehicles (SPVs)—entities created to hold assets—and derivative products like those offered by crypto exchange OKX. Anthropic has explicitly banned SPVs, stating that any transfers to them are void. The company’s enforcement of transfer restrictions aims to prevent transactions where the underlying equity claim may be fraudulent, a risk highlighted by liquidations such as the FTX bankruptcy.

Why it matters

Anthropic’s aggressive stance against secondary market platforms underscores the growing friction between high investor demand for AI equity and the strict transfer restrictions private companies use to maintain control over their cap tables.