OpenAI and Anthropic Weighed Mutual AI Tests. Palantir CEO Says One May Never List

OpenAI and Anthropic came close earlier this year to a legally binding deal letting each test the other’s artificial intelligence models for vulnerabilities and hidden safety risks, The Information reported. It is unclear whether the agreement was finalized.

Days before that report, Palantir chief executive Alex Karp questioned on whether one of the two will ever reach public markets. His target was Anthropic.

Inside the OpenAI and Anthropic Testing Deal

Each side would have received programming access to the other’s commercial models, the freedom to run its own vulnerability tests, and a bar on keeping the other’s data. Unreleased systems were left out.

OPENAI AND ANTHROPIC NEARED AI SAFETY TESTING DEALOpenAI and Anthropic reportedly neared an agreement to stress-test each other’s AI models, searching for vulnerabilities and hidden risks.It’s unclear whether the deal was finalized before OpenAI encountered incidents…

— *Walter Bloomberg (@DeItaone) September 21, 2026

The talks came before a run of incidents in which OpenAI’s unreleased agents reportedly reached internal and external systems in unexpected ways.

OpenAI has since paused one form of reinforcement learning, a training method that rewards a model for getting things right, for two weeks. It also moved a quarter of its production engineering team onto security work temporarily, and built monitoring that can consume compute equal to about a fifth of the workload it watches.

The company published six cases of concerning model behavior this month. A one-off swap in 2025 had already produced awkward results, with OpenAI finding Anthropic’s models more likely to conceal rule-breaking and Anthropic finding OpenAI’s more willing to assist with harmful requests.

Karp Doubts an S-1 Ever Arrives

Elsewhere, a CNBC host asked Palantir CEO Alex Karp how the liability he describes would be written into an S-1, the registration document a company files before selling shares to the public. He questioned the premise.

“You’re assuming that there will be an S-1. Now… okay, maybe there will be,” he said.

His case is that a company claiming unlimited downside ends up asking the government to absorb it, and paying with about half the business. The first line of defense, he said, should be ordinary civil and criminal liability for builders who act recklessly.

He directed that at Anthropic chief executive Dario Amodei, whom he called shrewd and ethical. Asked in the same interview whether OpenAI wanted the same treatment, Karp ruled it out.

“No, very no. I think these are very different things.”

Anthropic is preparing its public markets debut, while Sam Altman said on September 12 that OpenAI would not list in 2026 because its safety work was unfinished.

BREAKING: Palantir's Alex Karp says OpenAI will never IPO.His theory: nationalization is the only real exit.When asked what the S-1 risk factors look like, Karp's answer was simple: there is no S-1.The liability exposure from frontier AI is so large that no public market… pic.twitter.com/0Hj3w405IO

— Guillermo Flor (@guilleflorvs) September 21, 2026

Palantir sells rival software to governments and large enterprises, which gives Karp a stake in how the argument lands.