Anthropic Files Confidential S-1, Racing OpenAI to a $1 Trillion IPO

Anthropic has taken its first formal step toward going public. The company behind Claude announced that it confidentially submitted a draft registration statement on Form S-1 to the U.S. Securities and Exchange Commission for a proposed initial public offering of its common stock. That is the full extent of what Anthropic has officially disclosed. No share count. No price. No timeline. The announcement was published under Rule 135 of the Securities Act and explicitly states it is not an offer to sell securities.

What the filing does is start a clock. It gives Anthropic the option to go public after the SEC completes its review, with the proposed offering depending on market conditions and other factors. The SEC reviews the draft privately, allowing the company to address any issues before anything becomes public. Only after that review wraps up does Anthropic have the option to move forward , and it is not obligated to.

The backdrop: a company that just tripled in value

To understand why this filing matters, you need the context of what happened just days before it. Anthropic closed a $65 billion Series H round at a $965 billion post-money valuation, marking what could be the AI startup's final private fundraise before debuting on the public markets. The newest round was led by Altimeter Capital, Dragoneer, Greenoaks and Sequoia Capital, and almost triples Anthropic's valuation from February, when it was worth $380 billion.

The revenue trajectory behind that valuation is striking. Since the Series G in February, adoption has continued to grow across global enterprise customers, and run-rate revenue crossed $47 billion earlier in May. That revenue base grew from roughly $9 billion run-rate at the end of 2025 to $47 billion by May 2026. Investors are clearly pricing the slope, not the snapshot.