Elon Musk’s rocket company SpaceX has confidentially filed to go public, firing the starting gun on what is expected to be the biggest initial public offering in history.

The Texas-headquartered company filed paperwork with the Securities and Exchange Commission this week for the listing, according to two people familiar with the matter.

Confidential filings allow companies to advance their listing plans without publicly revealing their financials. SpaceX last month acquired Musk’s loss-making AI startup xAI for $250 billion.

SpaceX was seeking to raise about $75 billion and was targeting a valuation of around $1.75 trillion, according to people familiar with the matter. In the US, only Nvidia, Apple, Alphabet, Microsoft, and Amazon have higher market capitalizations. SpaceX was valued at around $90 billion as recently as 2022.

SpaceX did not immediately respond to a request for comment.

The IPO, which would dwarf the $29 billion raised by oil major Saudi Aramco in 2019, is expected sometime in June, potentially coinciding—at Musk’s behest—with a rare planetary alignment and the billionaire’s 55th birthday.