GPT-5.5 Instant: ChatGPT's New Default Model in 2026
May 6, 2026
OpenAI's GPT-5.5 Instant replaces GPT-5.3 as ChatGPT's default model on May 5, 2026, cutting hallucinations 52.5% on medicine, law, and finance prompts.
#gpt-55
DeepSeek V4: Open-Weight Frontier at 1/7 the Cost
May 2, 2026
DeepSeek V4 ships 1.6T MoE open weights with 1M-token context: 80.6% on SWE-bench Verified at $1.74/$3.48 per million — roughly 1/7 the output cost of Claude Opus 4.7.
GPT-5.5: OpenAI's First Retrained Base Since GPT-4.5
April 24, 2026
OpenAI released GPT-5.5 on April 23, 2026 — the first fully retrained base since GPT-4.5. Benchmarks, $5/$30 API pricing, 1M context, and Opus 4.7 compared.