When one sector starts hogging the buffet
The S&P 500 has developed a serious tech habit. According to The Kobeissi Letter, Information Technology now makes up a record 39% of the index’s total market value — bigger than the dot-com peak and, frankly, big enough to make diversification blush.
AI is doing the heavy lifting
This isn’t just a random spreadsheet quirk. The rally has been fed by AI enthusiasm, which has kept megacap tech and its neighbors in the supply chain doing most of the lifting while the rest of the market plays backup vocals. The result: the index has been up in 11 of the last 13 weeks, with a handful of monster runs that would make momentum traders very happy and risk managers very sweaty.
Why investors should care
Here’s the catch: concentration cuts both ways. When a narrow slice of stocks is doing the work, the whole market gets more sensitive to whatever spooks that group — inflation, rates, geopolitical energy shocks, you name it.
- A hotter inflation print could revive rate-hike fears.
- Higher rates usually hit high-multiple tech first.
- Valuations are already stretched, with the S&P 500 around 20.1x forward earnings.
Big picture: the market’s been riding the AI wave like a surfboard in perfect weather. Just remember that when the tide turns, the same narrow leadership can make the drop feel a lot steeper.