Elon Musk's SpaceX is acquiring his artificial intelligence (AI) start-up, as the billionaire continues to consolidate some of his many business interests.

SpaceX confirmed the deal to acquire xAI, a smaller firm known for its Grok chatbot, posting a memo from Musk about the merger on its website.

In the note, Musk said the combination would form an "innovation engine" putting AI, rockets, space-based internet, and media under one roof.

Terms of the deal were not disclosed. However, a source familiar with the matter said it valued xAI at $125bn (£91bn) and SpaceX at $1tn, making it the most valuable private company ever.

Last month, Musk's electric car company, Tesla, also announced it had invested $2bn into xAI.

Musk told Tesla investors at the time that he envisioned xAI functioning as an "orchestra conductor" for Tesla factories employing autonomous robots.

At the same time, Musk also said Tesla would stop the manufacture of two car models in favour of producing robots - one of the most significant pivots the company has made.

Tesla moved forward with the xAI investment despite objections from some shareholders, who had questioned the decision to divert resources to another Musk firm. In a vote last year, abstentions and votes against the idea outnumbered those who approved.

SpaceX is also reportedly planning to list its shares for public trading.

Emily Zheng, a senior analyst at PitchBook, said the xAI deal has all the hallmarks of a company preparing for a public listing.

"The sheer cost of compute, infrastructure, and energy is why we are seeing many of venture's most valuable startups like SpaceX prepare to go public this year," Zheng said.

"Consolidating these companies ahead of an IPO allows SpaceX to present a differentiated, capital-efficient growth narrative to public investors."

IPO stands for Initial Public Offering, and this is when a private company first sells its stock to the public on a stock exchange.

In the SpaceX memo announcing the xAI merger, Musk said he believed space would provide a solution to the energy needs of AI firms.

"In the long term, space-based AI is obviously the only way to scale," he wrote.

He said launching AI satellites from Earth would be the "immediate focus", but added that the deal would also help advance his bigger ambitions.

"The capabilities we unlock by making space-based data centres a reality will fund and enable self-growing bases on the Moon, an entire civilisation on Mars and ultimately expansion to the Universe," he wrote.

Neuralink and The Boring Company now appear to be the only two smaller Musk companies that have not been brought under one of his larger operations.

xAI started out as a segment of X, formerly known as Twitter, after Musk acquired the social media platform in 2022, using its access to real-time text and information as AI training data.

By spring of 2025, xAI was independently incorporated and valued more highly by investors than X.

The AI company acquired the social media platform in an all-stock deal, with Musk saying the merger would "combine the data, models, compute, distribution and talent".

xAI's main product, Grok, has been scrutinised several times for its AI image-generation feature.

In recent weeks, the European Commission and UK watchdog Ofcom both launched investigations into X over concerns that Grok was used to create sexualised images.

xAI said in January that it had imposed restrictions on Grok users that limit image editing.