Spread is the gap between a brand's best and worst rank across AI models — the disagreement signal. A spread of 0 means every model agrees; a wide spread means the models see the brand very differently.
Borrowed from markets, where spread measures disagreement about price. If ChatGPT ranks a brand #1 but Gemini ranks it #7, the spread is 6 — and that volatility usually traces to a real difference in the sources each model reads or the use cases it emphasizes.
Wide spreads are opportunities. A brand with a top rank on one model has already proven the recommendation case; closing the spread on the lagging models is a more tractable goal than entering a ranking from zero.