Nemotron 3 Ultra went live June 4. Here's the call that works. (opens in new tab)

NVIDIA shipped Nemotron 3 Ultra on June 4, 2026 — its largest open-weights model and the new high-water mark for US open releases. Before you wire it into an agent harness, here is exactly what landed and where it sits on the leaderboard. What NVIDIA Launched on June 4: Specs and Leaderboard Position Nemotron 3 Ultra is a 550-billion-parameter hybrid Mamba-Transformer mixture-of-experts (MoE) model with up to roughly 55B active parameters per token — about 90% sparsity — released by NVIDIA on...