Where Data Tells the Story
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Nvidia's share price jumped 5 percent at the opening bell on Thursday, after the company had blown away expectations in its third-quarter earnings report on Wednesday. Nvidia's record quarter, which was accompanied by a bullish outlook for the current quarter, could be the catalyst for a year-end rally, as no company is currently watched more closely than Nvidia, the linchpin of the AI revolution. But it's not only Nvidia's symbolic role as the AI poster child that has the potential to move markets, it is its sheer size as the world's most valuable company as well.
Due to the fact that the S&P 500 is a market-cap-weighted index, the performance of mega cap companies such as Nvidia and Apple and Microsoft, both valued at more than $4 trillion, is particularly important to its overall performance. According to Howard Silverblatt, Senior Index Analyst at S&P Dow Jones Indices, Nvidia has once again been the biggest driver of the S&P 500's performance this year. As of October 31, the index had returned 17.5 percent in 2025, with Nvidia alone accounting for nearly 20 percent of the index's overall gain. That puts the company ahead of Alphabet, Microsoft and Broadcom, who accounted for 10.2, 10.1 and 8.2 of the index' year-to-date return, respectively.
At the other end of the scale, UnitedHealth was the largest negative contributor to the index's performance, followed by Fiserv, Salesforce and Accenture. All of these companies saw their share prices drop by 22 (Saleforce) to 68 percent (Fiserv), but due to their limited weight in the index, their performance only accounted for minus 4.9 percent of the index's overall performance, dragging its return down 0.87 percentage points on aggregate.