Anthropic raises $65B at $965B valuation, releases Claude Opus 4.8, plans wider Mythos rollout

Anthropic closed a $65 billion Series H funding round at a $965 billion valuation, making it the world's most valuable AI startup and surpassing rival OpenAI's $852 billion valuation from March 2026.

The numbers

The Series H was led by Altimeter Capital, Dragoneer, Greenoaks, and Sequoia Capital, with participation from Capital Group, Coatue, D1 Capital Partners, GIC, ICONIQ, and XN. Of the $65 billion total, $15 billion represents previously committed investment from cloud providers, including $5 billion from Amazon.

Anthropic's valuation has jumped from $380 billion in its February Series G to $965 billion—a 154% increase in three months. The company reports annualized run-rate revenue of $47 billion as of May, up from $10 billion at the end of 2025.

Claude Opus 4.8 specifications

Anthropic released Claude Opus 4.8, just over a month after Opus 4.7. Pricing remains unchanged at $5 per million input tokens and $25 per million output tokens. However, "fast mode"—a higher-speed API configuration—is now three times cheaper than it was for 4.7.

According to Anthropic's evaluations, Opus 4.8 shows substantially lower rates of misaligned behavior including deception and cooperation with misuse compared to 4.7. The company claims the model is approximately four times less likely than 4.7 to let code flaws pass unremarked.

On benchmark evaluations from Cursor, Artificial Analysis, and Anthropic's Super-Agent benchmark, the model outperforms 4.7 on agentic coding and long-horizon tasks. However, Andon Labs found 4.8 performed worse than 4.7 on certain business tasks and adversarial benchmarks, characterizing it as more cautious. Some users have reported the model being overly restrained and refusing straightforward requests.

Mythos coming soon

Anthropic announced it expects to bring its Mythos-class models to all customers "in the coming weeks." Mythos, first reported by Fortune in March, is notable for advanced coding and cyber capabilities, including the ability to find software vulnerabilities and chain them together for sophisticated attacks.

The model has been available only to a select group of users for defensive security purposes. Anthropic previously stated it would not release Mythos widely until developing safeguards against malicious exploitation.

Infrastructure strain

CFO Krishna Rao said the funding would help serve "historic demand" for Claude. Anthropic has acknowledged struggling with computing infrastructure during peak hours. The company has since signed new compute deals, including a reported $1.25 billion per month agreement with xAI running through May 2029.

What this means

Anthropic's $965 billion valuation and $47 billion revenue run-rate represent the fastest growth trajectory in AI startup history, but also raise questions about sustainable unit economics at this scale. The simultaneous release of a more cautious Opus 4.8 and plans to deploy the offensive-capable Mythos model signal conflicting priorities between safety constraints and competitive pressure. The mixed user reception of 4.8's heightened refusals suggests Anthropic may be overcorrecting on alignment at the cost of usability—a trade-off that becomes harder to justify as the company prepares for a public offering.