The S&P 500 has notched 25 record highs so far in 2026, and according to 24/7 Wall St., most of that lift is coming from a narrow source: Nvidia and Micron.
The outlet frames the pairing as a surprise — "two stocks you might not expect are doing most of the heavy lifting," as its August 9 piece puts it. Nvidia is the better-known name of the two, the designer of the chips that power AI systems. Micron makes memory chips, the components that store and feed data to those processors.
24/7 Wall St. also argues that history suggests the run isn't finished, while adding a caveat: the article says history carries "a specific warning for investors who assume fresh highs mean" more of the same. The full reasoning behind both the bullish case and the warning sits behind the source article; the summaries circulating on Google News and Bing News don't spell out the historical data being cited.
What's worth understanding is the structure of the rally, not the forecast. The S&P 500 is weighted by company size, so a handful of very large stocks can pull the whole index to a record even if most of its 500 members are flat or falling. When two chipmakers account for much of the gain, an index fund that looks broadly diversified is, in practice, making a concentrated bet.
This matters because millions of ordinary retirement savers hold S&P 500 index funds and may not realize how much of their 2026 gains — and their downside risk — now rides on the semiconductor trade.