S&P Ex-AI Index Gains 2.4% as S&P 500 Falls Nearly 1%

The S&P ex-AI index rose 2.4% through Thursday while the S&P 500 fell nearly 1%, leaving the AI-excluded gauge with a 3.29-percentage-point weekly lead over the broader index.

The current spread puts the index on track for its second-largest weekly lead since early 2024. The only wider recent comparison was the week ended June 26, when the ex-AI index gained 2.3% as the S&P 500 lost roughly 2%, a 4.26-percentage-point difference.

The divergence was also pronounced Wednesday. The ex-AI index gained 0.61%, beating the S&P 500 by 1.72 percentage points for the fifth-largest daily gap in the ex-AI index’s favor this year.

Goldman Sachs and S&P Dow Jones Indices introduced the SPXXAI index in February. It tracks the S&P 500 after excluding companies with significant artificial-intelligence exposure through revenue, infrastructure or demand. The screen includes businesses tied to chips, data centers, networking and cloud computing. At launch, AI-related companies made up about 45% of the S&P 500.

The index’s history was back-tested to early January 2024. Goldman Sachs framed it as a way to measure or hedge exposure to the AI trade. Its performance can therefore diverge from the broader index as companies with significant AI exposure and those outside the screen post different returns.

That contrast comes amid concentration in the S&P 500. The combined market value of its five largest companies equaled that of its bottom 434 constituents, a comparison covered in a previous look at S&P 500 concentration. Over longer periods, the ex-AI index still trails the broader benchmark.