Open-weight models hit 29% of production AI traffic — on under 4% of the spend

Vercel's AI Gateway Production Index for June 2026 reports open-weight models nearly tripled their token share since April to 29% — while accounting for less than 4% of spending. Overall token volume grew 29% and spend 27%, with the average price per token flat after May's ~20% rise; DeepSeek alone carried 22.6% of token volume while Anthropic led spending at 61%.

What it means Production traffic says a big slice of the market already moved routine workloads to open-weight models — worth re-checking which of your workloads still need frontier prices.