**Elon Musk Escalates Legal Battle Against OpenAI, Adds Microsoft and Reid Hoffman**

In a move that intensifies his ongoing dispute with OpenAI, Elon Musk has revived a lawsuit against the artificial intelligence company he co-founded, this time also implicating tech giant Microsoft. The amended legal complaint, filed on Thursday, accuses both OpenAI and Microsoft of operating a monopoly, and names LinkedIn co-founder Reid Hoffman as an additional defendant.

The lawsuit is a continuation of Musk's previous legal actions against OpenAI, which he initiated earlier this year. These suits have alleged that the company violated the founding principles agreed upon when it was established in 2015. Microsoft has chosen not to comment on the revived lawsuit, while OpenAI has strongly denied Musk's accusations. An OpenAI spokesperson described Musk's latest filing as "baseless," and noted that this is his third attempt to reframe his claims within the past year.

Thursday's legal filing updates a lawsuit originally submitted in a California court in August. The lawsuit accuses OpenAI of morphing from a "tax-exempt charity to a $157bn (£124bn) for-profit, market-paralysing gorgon." Additionally, it claims that Microsoft and OpenAI have used their monopolistic power to stifle competition in the AI sector, including Musk's own company, xAI. The complaint states that these actions have unjustly enriched the defendants by hundreds of billions of dollars, at the public's expense and Musk's detriment.

OpenAI, established in 2015 with the goal of creating artificial general intelligence (AGI), transitioned to a "capped profit" model in 2019 to attract investment. Microsoft initially invested $1 billion into OpenAI, further extending this to a multi-billion dollar partnership in 2023. The lawsuit also implicates OpenAI CEO Sam Altman, alleging "rampant self-dealing."

Musk's initial lawsuit in March argued that OpenAI's new structure effectively turned it into a "closed-source de facto subsidiary" of Microsoft. OpenAI has countered these claims, highlighting that Musk himself once supported the for-profit structure and had even sought "absolute control" of the company.

The renewed claims by Musk coincide with US President-elect Donald Trump's decision to select Musk for a government role focused on cost-cutting and reducing bureaucracy in anticipation of his return to the White House next year.