OpenAI Is Winning Back Secondary-Market Investors

For most of this year, investors wanted Anthropic and Anthropic only. OpenAI sat on the sidelines, bruised by slowing growth, executive departures, and a legal fight with Elon Musk. But the narrative is shifting.

OpenAI has spent the past month reminding the market why it was once the only AI company worth talking about. The launch of GPT-5.6 Sol — the flagship model unveiled in June, followed by GPT-5.6 Terra and the cheaper Luna variant — along with the breakout success of its AI coding agent Codex, has reignited demand among secondary-market buyers.

“Interest in OpenAI has noticeably rekindled over the past month,” said Dave McClure, founder and managing partner of Practical Venture Capital, a firm that specializes in pre-IPO secondary shares.

Neither OpenAI nor Anthropic is publicly traded, so most investors access them through secondary markets — buying shares from employees or early backers. These markets are fragmented and illiquid, and valuations are estimates rather than real-time prices. But the direction of travel is clear.

According to Glen Anderson, CEO of Rainmaker Securities, a commercial bank focused on private stock transactions, Anthropic still dominates: for every two buyers looking for OpenAI stock, five are chasing Anthropic. But the gap is narrowing. “A month ago, we saw very limited demand for OpenAI. Now you’re starting to see OpenAI shares being bid on more frequently,” Anderson said.

Independent benchmark tests show GPT-5.6 Sol is competitive with the industry leaders, though it still trails Claude’s latest Mythos and Fable models. That hasn’t stopped investors from circling back.

“Investors are coming back to OpenAI,” said Adam Crawley, co-founder of Augment, a trading platform for pre-IPO tech companies.

Mark Klein, president and CEO of Neostellar, which provides investment access to late-stage startups, said an OpenAI executive told him last week that the company’s two main enterprise platforms have reached 900 million cumulative active users. Those platforms are Codex — an AI agent built for complex software engineering tasks — and ChatGPT Work, a recently launched cloud-based assistant designed for multi-step professional workflows.

“The pace of growth is notable because it suggests AI agents are moving beyond their initial developer-focused use case into broader professional workflows,” Klein said. “OpenAI seems to be working on converting improving model capability into durable, sustained demand across coding, research, and knowledge work.”

Anthropic had been the more attractive investment for most of the past year, partly because its stock traded at a significantly lower price than OpenAI’s. That gap has since reversed. Some traders now see buying relatively undervalued OpenAI shares as a hedge against Anthropic exposure.

Business Insider reported last week that Anthropic’s secondary-market valuation has surged to $1.2 trillion. OpenAI, by comparison, is valued at approximately $933 billion according to Caplight, a secondary trading platform — a 20% increase over the past three months.

Sam Altman acknowledged on X last week that OpenAI’s recent performance hasn’t been strong. “The past 12 months have not been our best period, and that’s mostly on me,” he wrote. “But the next 12 months will be our best 12 yet.”

Altman posted that on the same day Chinese AI startup Moonshot AI released its Kimi K3 model, which the company described as one of the largest open-weight AI systems globally.

McClure cautioned that OpenAI still faces serious headwinds. “Pressure from Chinese AI companies and open-source competitors continues, and that competition will likely affect OpenAI’s growth rate and margins,” he said. “There’s still a very high mountain to climb.”