OpenAI's GPT-4 held the top spot on the Epoch Capabilities Index (ECI) for about a year. The ECI is a composite measure of language model performance. According to Epoch AI researcher Jaeho Lee, that's far longer than any model since. OpenAI's o1 held the second-longest lead at just over three months, less than a third of GPT-4's reign. Since Claude 3 Opus dethroned GPT-4 in February 2024, the lead has changed hands 17 times. The median stay at the top per model was about seven weeks.

The chart can be read two ways. It shows how long rival labs needed to match GPT-4, a genuine outlier at launch. But it also shows that competition has gotten much fiercer since. No model can hold a comparable lead anymore, and the capability jumps between transitions are faster but smaller compared to GPT-4 and the era that began with reasoning models like o1-preview in fall 2024.