As investors scramble to get their hands on shares of AI companies like they're the last toilet paper roll in a pandemic, Anthropic has updated its website to deliver a very specific message: no, you cannot buy our shares from those guys.

The company named Open Doors Partners, Unicorns Exchange, Pachamama Capital, Lionheart Ventures, Hiive, Forge Global, Sydecar, and Upmarket as unauthorized platforms trying to peddle 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 blog post reads, in what is probably the least fun way to ruin an investor's day.

Forge Global, for its part, claims to have been included erroneously, telling TechCrunch it is "working with Anthropic to remove Forge’s name from this alert." Forge says it does not facilitate transactions without the explicit approval of the company, which is basically the secondary market equivalent of saying "I have a hall pass."

The warning comes amid a surge in platforms offering exposure to AI companies' shares via secondary markets, "tokenized" securities, special purpose vehicles (SPVs), or secondary market holdings. Anthropic, rumored to be raising fresh funding at a $900 billion valuation - which, let's be honest, is a lot of commas - has been in such demand that some secondary market brokers told TechCrunch last month it's one of the "hardest" stocks to source.

Over the past year, some crypto companies, like exchange OKX, have spun up investment products selling exposure to AI companies. These often take the form of pre-IPO perpetual futures contracts, which are derivative instruments that track the value of private companies on secondary markets but don't offer ownership of actual shares - essentially, betting on a horse you'll never actually ride.

SPVs are different from those derivative systems, offering investors a chance to buy shares of an entity that holds at least some stake in Anthropic. That equity could be from an official investor, or have been acquired when an investor is forced to liquidate its holdings - as happened during the bankruptcy of FTX, which is the financial equivalent of a yard sale after a divorce. In other cases, the equity claim may be entirely fraudulent.

Anthropic says both its preferred and common stock are subject to transfer restrictions, meaning any share sale or transfer not approved by its board of directors will be considered invalid. According to Anthropic, any third-party platform (specifically SPVs and retail investment firms) that claims to sell its shares directly or using forward contracts are unauthorized to do so. The company's blog is quite clear: "We do not permit special purpose vehicles (SPVs) to acquire Anthropic stock and any transfer of shares to an SPV are void under our transfer restrictions. Offers to invest in Anthropic’s past or future financing rounds through an SPV are prohibited."

In other words, if you want Anthropic shares, you're going to have to wait until they let you in the door. Until then, you can keep refreshing your portfolio and pretending that's a hobby.