Elon Musk and Sam Altman founded OpenAI together, but now trade barbs. Here’s the history of their working relationship and feud.

• Elon Musk helped found OpenAI, but he has frequently criticized it in recent years.
• Musk filed a lawsuit against OpenAI in August and just amended it to include Microsoft. 
• Here’s a history of Musk and Altman’s working relationship.

Elon Musk and Sam Altman lead rival AI firms and now take public jabs at each other — but it wasn’t always like this.

Years ago, the two cofounded OpenAI, which Altman now leads. Musk departed OpenAI, which created ChatGPT, in 2018, and recently announced his own AI venture, xAI.

There was enough bad blood that Musk sued OpenAI and Altman, accusing them in the suit of betraying the firm’s founding principles, before dropping the lawsuit. The billionaire then filed a new one a few months later, claiming he was “deceived” into confounding the company. He just amended it to include Microsoft as a defendant, and his lawyers accused the two companies of engaging in monopolistic behavior.

Here’s a look at Musk and Altman’s complicated relationship over the years: