Tech Has Its Worst Week in 18 Months as the Average Stock Keeps Climbing

The technology sector had its roughest week in about a year and a half, and the shift it signals may matter more than the losses themselves. Tech has carried the S&P 500 for much of the recent rally, so a week like this draws attention from investors who have grown used to the index moving with a small group of large companies.

The contrast is clearest when you look at how the index is built. The standard S&P 500 weights each company by its market value, which gives the biggest names outsized influence. An equal-weighted version treats all 500 stocks the same, so it reflects the experience of the typical company in the index rather than the handful that dominate the headline number. That version posted a second consecutive weekly gain, which is a sign that strength is spreading beyond the market's largest stocks.

That breadth is the part worth watching. When leadership narrows to a few sectors, the market is more exposed to a single group of companies turning sour. When gains spread across industries, the advance tends to rest on a wider base. The latest week hints at the second situation, though two weeks is a short window and does not establish a trend on its own.

Investors should also be cautious about reading too much into one week. Technology stocks are volatile, and a sector that drops sharply in one stretch can recover just as quickly. The more useful question is whether the weakness in tech persists while other sectors keep advancing. If it does, portfolios built around market-cap indexes may need a closer look at how much they depend on a few large companies.

For now, the message from the week is that the market is no longer resting on tech alone. Whether that holds will depend on the weeks ahead.