Nebius agreed on May 1 to acquire Eigen AI for approximately $643M in cash and Class A shares, calculated on a 30-day weighted average stock price. Eigen AI, founded by MIT Han Lab alumni, optimizes full-stack inference across post-training, compression, context engineering, and GPU kernels for major open-source models including Llama, Qwen, and DeepSeek. Nebius says the deal embeds Eigen's optimization stack directly into Token Factory, removing a bottleneck that forced customers to bring their own inference engineering; popular models like GPT-OSS-120B and Qwen3 Coder 480B had already ranked in the top three fastest implementations in AA benchmark tracking under the earlier partnership.