Anthropic last week named eight firms whose share offerings it said would be void and explicitly barred purchases through special purpose vehicles, sharply escalating its campaign against unauthorized secondary trading.
That warning hit a fast-growing market for pre-IPO AI stakes, where family offices, wealthy individuals and retail buyers had used brokers, funds and SPVs to gain exposure to Anthropic and peers.
Publicly traded funds advertising Anthropic exposure fell after the notice, and one closed-end fund said its share price has dropped about 25% as investors questioned whether underlying holdings were valid.
Platforms singled out by Anthropic, including Hiive and Unicorns Exchange, said they handled approved or legitimate deals, while OpenAI said it has also acted against unauthorized platforms offering its shares.
The clash lands as Anthropic discusses new funding at a valuation above $900 billion, underscoring how booming shadow markets in elite private companies are colliding with weak disclosure and ownership safeguards.
Billions in Anthropic shares were just declared 'void.' What legal nightmare awaits investors who bought into the AI dream?
As AI titans crush the secondary market, is this a necessary cleanup or a move to consolidate power before their IPOs?
Anthropic’s Trillion-Dollar Share Ban: Market Shockwaves and the Future of Private AI Investing
Overview
In May 2026, Anthropic declared all unauthorized sales or transfers of its shares void, cracking down on informal trading and shadow ownership structures. This bold move, mirroring similar actions by OpenAI, reflects a broader effort by leading private tech firms to assert control over their equity. With a soaring valuation and ambitious IPO plans, Anthropic needed to maintain a clean cap table and strong governance to justify its premium valuation and sustain investor confidence. By taking decisive action, Anthropic aims to secure its future and set a new standard for transparency and control in private markets.