Mistral Large 4 opens its trillion-parameter weights — and open AI splits in two

On 29 October 2026 Mistral published the weights of Large 4, nicknamed Le Chonk — a trillion-parameter open-weight model for coding and cyber defence — three weeks after its public preview. At the same time IBM's Granite Switch shows the opposite open strategy: keep the base small and swap in specialist adapters. Here is what each path costs, what each licence really allows, and how to choose.