Santoli's Tuesday market wrap-up: S&P 500 pulls back from record highs as investors rethink the AI trade

(These are the market notes on today's action by Mike Santoli, CNBC's Senior Markets Commentator.) Another one of the market's occasional rethinks of the beloved AI-investment theme strikes some of the heavily owned leaders of the group, pressuring the big-cap indexes but so far sparing the majority of stocks from significant damage. Questions over whether Nvidia 's $100 billion pledged investment in OpenAI to fund the development of Nvidia-centric data centers seems to have prompted a round of scrutiny over a possible eventual endgame of overcapacity and overlapping partnerships and vendor relationships. Nvidia and Oracle shedding the most among the big names, while Microsoft 's announcement of a self-cooling chip has hit the power-management names such as Vertiv . This action in some cro