xAI's Grok 3, Mira Murati's startup, and Together AI's raise: This week's AI launches

Elon Musk’s AI startup, xAI, introduced its “most advanced model yet,” Grok 3, this week.

Grok 3, which was trained on xAI’s Colossus supercluster, combines reasoning capabilities “with extensive retraining knowledge,” the company said in a blog post. The AI model “displays significant improvements in reasoning, mathematics, coding, world knowledge, and instruction-following tasks,” xAI said, adding that it refined Grok 3’s reasoning skills with large-scale reinforcement training.

xAI also unveiled Grok 3 mini, and said both AI models are still training.

Former OpenAI chief technology officer Mira Murati launched an AI startup this week called Thinking Machines Lab. The AI research and product company, which Murati helped found after leaving OpenAI in September, wants to “make AI systems more widely understood, customizable and generally capable,” it said in a blog post.

The current team includes other OpenAI alumni, including former vice president of research Barret Zoph and former vice president of safety research Lilian Weng.

Together AI, an AI Acceleration Cloud for building AI applications with open-source AI models, announced a $305 million Series B funding round this week. The funding round was led by General Catalyst, co-led by Prosperity7, and values Together AI at $3.3 billion.

The company is planning to expand its AI Acceleration Cloud by deploying Nvidia’s (NVDA) Blackwell chips.

“This investment will accelerate our leadership as the preferred AI Cloud for building modern AI applications with open source models,” the company said in a blog post, adding that it has worked with companies such as Salesforce (CRM) and The Washington Post to build AI applications.

U.K.-based legal AI company Luminance announced a $75 million Series C funding round this week. The oversubscribed round was led by Point72 Private Investments and is the largest funding round for a pure-play legal AI company across the U.K. and Europe. The company develops AI that can automate and augment legal contracts for businesses.

“This funding is all about innovation, expansion and scaling,” Luminance CEO Eleanor Lightbody said in a statement. “It supercharges our US growth, where 40% of our revenue is already generated, and will fuel key hires and new offices across the US, APAC and Europe. It also accelerates innovation at our Cambridge R&D hub as we expand Luminance’s AI platform to legal adjacent use cases in procurement and compliance.”

Lambda, a GPU cloud company, announced a $480 million Series D funding round this week. The funding round was co-led by Andra Capital and SGW and brings the company’s total equity capital to $863 million.

The funding will be used to expand Lambda’s Cloud Platform, the company said in a blog post, adding that it is currently scaling AI infrastructure and software for developers to train, fine-tune, and deploy AI models faster. The company will also be developing its Lambda Chat, which hosts open-source models such as DeepSeek’s R1.