After months of speculation about whether OpenAI or Anthropic would be first in their race to IPO, Anthropic on Monday reached a key milestone: filing to kick off the process with the U.S. Securities and Exchange Commission.

The filing sets the stage for what’s sure to be a massive IPO. As of its fundraise last week, Anthropic is being called the world’s most valuable startup, with a post-money valuation of $965 billion. That tops the $852 billion post-money valuation of OpenAI, which is its biggest rival.

Anthropic chose to submit its draft registration statement to the SEC confidentially, according to a blog post from the company, meaning key details typically included in that form about a company’s operations — like potential risks to its business, executive compensation, and other financials — won’t become public until later on in the process.

The news comes less than two weeks before SpaceX’s planned June 12 IPO. Elon Musk’s SpaceX — which owns xAI and also has a newly-minted deal with Anthropic that has the latter paying $15 billion per year to use SpaceX data centers — is currently set to raise $80 billion in its public debut, which would make it the largest IPO in history.

The filing also comes shortly after OpenAI came out ahead in its high-profile legal battle with Musk, when a judge dismissed all claims due to the statute of limitations.