OpenAI Upgrades ChatGPT Default Model to 'GPT-5.5 Instant'... Significantly Strengthening Reasoning and Memory

On May 5, 2026, OpenAI quietly replaced the foundation of ChatGPT, the world's most popular AI interface, with GPT-5.5 Instant. This is not just an iterative improvement; it is the result of addressing hallucinations and memory issues that users have long complained about, while maintaining the latency of previous models. For the millions of users who use ChatGPT daily, the dawn of this 'Instant' era signifies a transition from a simple chat interface to a reliable agent partner that remembers context from weeks ago, not just hours.

OpenAI stated that with this upgrade, GPT-5.5 Instant provides a smarter, clearer, and more personalized experience. In particular, it features the ability to remember conversations from the previous week, supporting a seamless user workflow. Responses have become more concise, and errors that distort factual information have been reduced. This contributes to lowering the fatigue users experience when interacting with AI and increases its value as a practical productivity tool.

GPT-5.5 is more capable of performing computer-based tasks than previous models and is showing significant gains in scientific and technical research workflows. We feel this model can redefine professional knowledge work.

The name 'Instant' suggests that it has simultaneously secured fast response speeds and high-level reasoning capabilities. OpenAI has achieved a technical balance that implements frontier-level performance in coding and reasoning while maintaining the same latency per token as GPT-5.4 in a real-time service environment. Additionally, it has been optimized to use fewer tokens for Codex tasks, maximizing efficiency. These architectural improvements serve as an essential foundation for performing complex tool usage and expert-level knowledge tasks.

A Leap in Reasoning Capabilities Proven by Benchmarks

GPT-5.5 Instant recorded overwhelming figures in the ARC-AGI benchmark, a performance metric. It scored 95.0% on the verified ARC-AGI-1, surpassing GPT-5.4 (93.7%) and Claude Opus 4.7 (93.5%). In ARC-AGI-2, which measures high-difficulty reasoning, it achieved 85.0%, widening the gap significantly with Gemini 3.1 Pro (77.1%). These results show that GPT-5.5 Instant has moved beyond being a simple language model to a stage capable of high-level abstract reasoning.

• Securing real-time responsiveness by maintaining the same latency per token as GPT-5.4
• Increasing cost efficiency by reducing token usage in Codex tasks
• Strengthening complex problem-solving capabilities by supporting 'xhigh' reasoning settings during evaluation
• Ensuring personalized conversation continuity through improved long-term memory

This dramatic performance improvement was made possible through close hardware collaboration with NVIDIA. The two companies set a technical milestone by jointly building the first GB200 NVL72 cluster consisting of 100,000 GPUs. NVIDIA's infrastructure supports large-scale models like GPT-5.5 Instant to be served to millions of users in real-time. OpenAI provides feedback on the hardware roadmap, while NVIDIA maintains a symbiotic relationship by granting early access to the latest architectures.

Market reactions are mixed. Microsoft (MS) shares fell about 14% year-to-date as paradoxical views emerged that increased efficiency in AI models could actually erode the AI premium. Changes are also being detected in corporate alliances, such as the termination of the exclusive AGI contract with MS and the introduction of OpenAI models to AWS (Amazon Web Services). On the other hand, semiconductor-related stocks such as Intel (+13.36%) and Micron (+10.79%) showed strength, reflecting high market interest.

Journey Toward an AI Super App

The emergence of GPT-5.5 Instant will be a significant turning point on the path toward ChatGPT becoming an 'AI Super App' that integrates all functions. The ability to perform computer tasks as an agent and assist in scientific research beyond simple text generation is fundamentally changing the role of artificial intelligence. OpenAI has raised technical maturity to the next level with this model, which is expected to become the standard for even more powerful models to be released in the future.

In conclusion, this update in May 2026 has served as an opportunity for AI to firmly establish itself as core infrastructure across industries, moving beyond a daily conversation partner. As technical leaps and strategic market changes align, the AI ecosystem is entering a new phase. How both users and companies leverage the possibilities of this new 'Instant' era is expected to be the key to future technological competition.