Anthropic

Meet Sol and Luna

Both models build on GPT-6 Astra, the flagship OpenAI released earlier this month, bringing “much of its strengths into faster and more affordable models,” the company says.

• GPT-6 Sol is the all-rounder, aimed at complex work like interactive and agentic coding.
• GPT-6 Luna is the lightweight option, for “high-volume tasks with a clear goal, like summarizing documents, extracting information, or answering quick questions.” It’s the cheapest model in the GPT-6 family.

GPT-6 Sol makes about half as many mistakes as its predecessor, reaching Astra-level reliability at much lower cost.

OpenAI

The price cut

The headline number is price. Per million tokens, the new API rates are:

• GPT-6 Sol: $2 input, $10 output
• GPT-6 Luna: $0.10 input, $0.50 output

That’s 50% below the promotional pricing of the GPT-5.6 models, a cut OpenAI attributes to improvements in caching and inference. “We want the OpenAI API to feature the best model at every price point and modality,” CEO Sam Altman said, according to Pulse 2.0.

The benchmarks, and a catch

At its highest reasoning setting, OpenAI says Sol scores 33.2% on AutomationBench, a test of business workflows, at about $0.27 per task. It also reports 56.4% on Agents’ Last Exam, 60.5% on the OSWorld 2.0 computer-use benchmark, and 68.8% on the DeepSWE v1.1 software engineering test, where Luna isn’t far behind at 66.6%.

OpenAI claims the new models beat Anthropic’s Fable and Opus models. But the head-to-head numbers it published compare Sol with Claude Opus 5, which scored 26.9% on AutomationBench at 11 times the cost per task. That’s the model Anthropic replaced 90 minutes before OpenAI’s announcement, so how Sol stacks up against the brand-new Opus 5.5 is still an open question.

Anthropic’s move

Claude Opus 5.5 is the first model in Anthropic’s new 5.5 family. The company says it performs at the level of Claude Fable 5.1 on most work, costs 40% less to run than Opus 5, and generates output more than 30% faster. Its API price drops to $4 per million input tokens and $20 per million output tokens.

Anthropic is also removing the five-hour usage caps for Pro, Max, Team and seat-based Enterprise subscribers, and says Sonnet 5.5 and Haiku 5.5 will follow within weeks, TechCrunch reports.

How to get them

GPT-6 Sol and Luna are available now in ChatGPT Work and Codex for Plus, Pro, Business, Enterprise and Edu subscribers, and rolling out to the ChatGPT app and website throughout the day. Free and Go users can use Luna in the ChatGPT desktop app. Developers can call them in the API as gpt-6-sol and gpt-6-luna, and both are already available in GitHub Copilot.

Sources: OpenAI, TechCrunch, Decrypt, Pulse 2.0, TechCrunch (Opus 5.5), GitHub

It started with a resignation

Hubinger’s post on X was a response to a very public exit. Jacob Coxon, a researcher who spent the last three years doing pretraining research at both OpenAI and Anthropic, announced he was leaving with a thread that didn’t mince words:

I resigned from Anthropic today. I spent the last three years doing pretraining research at both OpenAI and Anthropic. Neither company is acting responsibly. They are racing straight to self-improving superintelligence and gambling with our lives.

Jacob Coxon

Coxon drew a distinction between the two labs: “At OpenAI, many have not deeply internalized the civilizational stakes. At Anthropic, the stakes are well-understood, but they are locked in a race to get there first.” According to Fox Business, he floated a temporary ban on improving model capabilities as one possible fix.

“Jacob is correct here”

Rather than push back on his former colleague, Hubinger agreed with him.

Jacob is correct here—we really do earnestly believe AI could kill all humans! I personally think it is >10% within the next decade.

Evan Hubinger, Alignment Science Lead at Anthropic

He then went a step further: “I believe Anthropic is trying its best, but we do not yet have a plan to solve alignment for superintelligence and are not clearly on track to.”

That’s a remarkable thing for a senior safety researcher to say publicly about his own employer, even at a company that has always been unusually open about catastrophic risk.

Not today’s models

Hubinger was careful to point out that the danger isn’t coming from the AI people are using right now. “As we say in our latest Risk Report, I think the risk from present models is low,” he wrote.

The concern both researchers share is recursive self-improvement: AI systems that meaningfully speed up the creation of even more capable AI. That’s no longer a thought experiment. Last week, Anthropic disclosed that Claude was leading 26% of the company’s model research and development as of August, up from essentially none in February, with around 90% of its R&D now happening in collaboration with Claude.

What Anthropic says

Fox Business says it reached out to Coxon, Hubinger, Anthropic and OpenAI for further comment, but its report didn’t include a response from any of them. When Anthropic published its R&D numbers, it said that “we should do everything possible to minimize the gap between what frontier labs know and what the public knows,” and committed to bringing in external, third-party safety evaluators.

Whether a better than 1-in-10 chance of extinction sounds alarming or alarmist to you, it’s worth remembering where the number came from: not a critic on the outside, but someone whose job is making Anthropic’s models safe.

Sources: CBS News, Fox Business, Spectrum News