The UK government's £500 million Sovereign AI initiative took its first equity stake in Callosum, a London startup founded by Cambridge PhDs that builds systems software to co-optimize models and workloads across heterogeneous chip architectures. Six further startups—Prima Mente, Cosine, Cursive, Doubleword, Twig Bio, and Odyssey—received up to one million GPU hours on UK AIRR supercomputers, with the government retaining right of first refusal on future investments. The fund also offers fast-track visa processing (decisions in one working day) and ten cost-free visas per company to help recruit international AI talent. Tech Secretary Liz Kendall framed the initiative as backing companies to "start in Britain, scale fast and compete globally."