ChatGPT maker OpenAI has warned against unauthorized opportunities to gain exposure to the company through a variety of means that include investments in SPVs (special purpose vehicles) that own OpenAI equity.

"All OpenAI equity is subject to transfer restrictions. This means that OpenAI equity cannot be directly or indirectly transferred unless the seller first obtains OpenAI’s written consent," the AI startup posted in a blog.

OpenAI also warned that any such transfer may also violate US federal or state securities laws.

The Sam Altman-led company also highlighted that while not every offer of OpenAI equity is problematic, it is possible that the firm offering to sell the sale of OpenAI's equity is attempting to circumvent its transfer restrictions.

"If so, the sale will not be recognized and carry no economic value to you," it added.

The warning comes as investors have increasingly used SPVs to buy stake in AI startups. 

Earlier this month, The New York Times reported that OpenAI has raised $8.3 billion in new funding, valuing the company at around $300 billion. This is part of the startup's broader strategy to secure $40 billion this year.

OpenAI is not the only startup warning against unauthorized investments through SPVs. The Business Insider reported that Anthropic has told Menlo Ventures not to invest in the startup through an SPV.

Last week, The Bloomberg reported that Anthropic is in talks to raise up to $10 billion in new funding, higher that the $3-$5 billion it was reportedly aiming to raise in July.