Nathan Lambert's 'Bets on Open Models, Mid-2026': The Moat Is Shifting From Base Model to the Best RLHF Pipeline and Preference Data

Interconnects (Nathan Lambert)·low signal

In his mid-2026 Interconnects analysis, Nathan Lambert argues post-training recipes have changed more in the past year than the prior three, dissecting multi-stage RL pipelines like Microsoft's MAI-Thinking-1 (specialist RL 'climbs' plus trace-distillation SFT). His thesis: once fine-tuning commoditizes, differentiation comes from who owns the best RLHF pipeline and labeled preference data, not the base weights. For builders, that points investment toward eval and preference-data infrastructure over chasing the latest base model.