The Open-Weight Frontier Gap

Arena Text, June 2026: the top closed model leads the best open model by 33 Elo and the best *dense* open model by 57; open weights at the frontier means 744B–1.6T MoEs, so Gemma 4 31B competes on a different axis (efficiency, edge deployment) — July 2026's Inkling adds a third open-weight strategy (fine-tunability, not the leaderboard), and Kimi K3 pushes the sparsity pole to 2.8T/104B while the open/closed gap on *agentic* Elo measures runs wider (35–61 points) than the chat gap; on the demand side, Ramp's card-spend index puts US business use of open/Chinese model-serving platforms at 5.8% of AI spenders, and 96.4% of those firms still pay OpenAI or Anthropic directly — currently additive, not substitutive