Elon Musk is combining rocket maker SpaceX with his artificial intelligence startup, xAI, as the combined entity gears up for a massive IPO.

The deal was announced on Monday in a blog post from Musk, who said he’s forming “the most ambitious, vertically-integrated innovation engine on (and off) Earth, with AI, rockets, space-based internet,” and its X social media platform.

The combined company is expected to price shares in an IPO that would value it at $1.25 trillion, Bloomberg reported. Public records with the state of Nevada obtained by CNBC indicate that the deal was completed on Feb. 2, with Space Exploration Technologies Corp. listed as the “managing member” of X.AI Holdings.

The transaction marks the largest tie-up in Musk’s vast business portfolio and brings together two companies that have been soaring in value on the private markets. SpaceX opened a secondary share sale last year at a valuation of $800 billion, while xAI was valued at about $230 billion in a $20 billion round that closed earlier this year.

Tesla, Musk’s electric vehicle maker and the source of most of his liquid wealth, said last week that it’s agreed to invest about $2 billion into xAI.