Investors still can't get enough of Anthropic.
As the AI giant races towards what could be one of the largest IPOs in history, its shares are changing hands on secondary markets at valuations as high as $1.5 trillion, even as competition from OpenAI and Chinese open-source models intensifies.
Anthropic's private market valuation has recently soared to as much as $1.5 trillion, a 25% increase over the past month, according to three secondary traders who spoke with Business Insider. The catch is that shares are incredibly tough to get.
"The few sellers on our books are around $1.5 trillion," said Glen Anderson, CEO of Rainmaker Securities, a merchant bank focused on private securities transactions. "Even at that number, there aren't a lot of sellers out there."
Anthropic was last valued at $965 billion in a funding round announced in May. In June, it filed paperwork to go public, with an expected public market debut in the next few months.
"People are trying to position themselves ahead of the IPO," said Adam Crawley, president of Augment, a marketplace to invest in private shares.
Since Anthropic is still private, the vast majority of investors buy on secondary markets, where existing stock is sold by employees or early investors. Some are legitimate, while others have involved suspect deals with high fees and byzantine ownership structures structured as SPVs, or special-purpose vehicles, which allow investors to pool their funds for a single, one-off deal.
Anthropic declined to comment for this story. On its website, it has become more explicit in cautioning against unauthorized stock sales and scams.
Some buyers have heeded the warnings and are being more choosy about which stock they buy, according to Aman Verjee, a general partner at Practical Venture Capital.
"Many buyers are now asking for direct cap table exposure," he said. "Demand for nested SPVs with indirect exposure, less reporting rights, or exposure to Anthropic's earlier rounds and common shares is softer, and I'm not seeing a lot of demand at $1.5 trillion for that, but there is some."
Soaring valuation even as competition increases
Anthropic's secondary valuation has continued to climb even as its competitors have been closing the gap.
OpenAI's answer to Claude Code, Codex, reached 5 million active monthly users in June, and the company's latest models, GPT-5.6 Terra and the lower-cost GPT-5.6 Luna, have been well received. At the same time, China's Moonshot AI has emerged as a more serious threat, with its Kimi models gaining traction as a far cheaper alternative.
OpenAI has seen a resurgence of interest from secondary buyers this summer. However, its price has stayed relatively flat, hovering around the $852 billion valuation of the funding round it closed in March with more supply, according to Crawley.
By contrast, Anthropic's valuation has continued to soar, and Crawley is seeing way more buyers than sellers.
"With an IPO coming soon, you don't have a lot of willing sellers," he said.