Anthropic on Monday announced that it has filed confidential IPO papers with the U.S. Securities & Exchange Commission.

Why it matters: Three companies could enter the U.S. public markets with valuations of at least $1 trillion -- something that never before has even happened once.

SpaceX is expected to be first, with its IPO anticipated later this month.

Both Anthropic and OpenAI are racing to be second.

Catch up quick: Anthropic last week raised $65 billion in Series H funding at a $965 billion post-money valuation, led by insiders Altimeter, Dragoneer, Greenoaks, and Sequoia Capital.

It was the largest "venture capital" round of all time and saw Anthropic leapfrog rival OpenAI on valuation.

Zoom in: Confidential IPO filings allow companies to solicit feedback from securities regulators before sharing their information with prospective investors.

If Anthropic moves forward, it will file a publicly available S-1, which would include financial data, risk factors, and more.

The actual IPO would come around a month later.

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