Anthropic just publicly named eight secondary market platforms — Open Doors Partners, Unicorns Exchange, Pachamama Capital, Lionheart Ventures, Hiive, Forge Global, Sydecar, and Upmarket — and declared that unauthorized share transfers through them are void. This isn't a policy dispute. It's a warning to every investor holding indirect exposure to Anthropic, SpaceX, or OpenAI through an SPV: if the company didn't approve the transfer, you don't own the shares. Here's how to verify your holdings before the window closes.