SemiAnalysis Measured the Open-Weights Catch-Up Time and Found It Halves Every Era, Now Down to Under Five Months

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SemiAnalysis published on August 21 that the open vs closed gap moves in cycles and closes roughly twice as fast each generation. Era 1 scaling: GPT-3.5 Turbo 75.7 vs Llama-2-70B 39.9, closed when DeepSeek V3 matched GPT-4o in December 2024. Era 2 reasoning: o1-preview led DeepSeek R1 by 12.1 points, closed by the R1-0528 checkpoint in an 8.5-month window. Era 3 agentic: Kimi K2.6 passed Opus 4.5 in 4.8 months and GLM-5.2 cleared GPT-5.2 in 6. The authors flag their own caveat that benchmarks miss productization.