OpenAI: GPT-6 far better at COBOL, Fortran and other legacy languages

On OpenAI's new MultiLangBench, GPT-6 Astra passes 87.4% of tests across 20 languages, up from about 38% for GPT-5.6 Terra. For COBOL migration, GPT-6.1 Sol reaches up to 97.9% accuracy.

Why it matters: Legacy code in COBOL and similar languages underpins banks and governments, and migration has been held back by scarce expertise. These are vendor-reported numbers on a new benchmark, but if they hold, modernization becomes a realistic AI workload.