Elon Musk's AI startup xAI has raised $6 billion in a Series B funding round valuing the company at $24 billion. Major investors in the round include Fidelity, Sequoia Capital, Andreessen Horowitz, Prince Alwaleed Bin Talal, and Kingdom Holding. The company's first major product is an AI assistant called Grok that is available to premium users of Elon Musk's social media platform X. Grok competes with AI models like GPT-4, Claude, and Llama and aims to provide an advanced language model. xAI is central to Elon Musk's turnaround plans for X after facing challenges since acquiring Twitter.