Why Just 5 Stocks Are Holding Up the Whole Stock Market

Five huge tech stocks made up 93% of the stock market's gains since late July, according to MarketWatch.

The S&P 500 tracks 500 big U.S. companies. Bigger companies count more in its math. Breadth means how many stocks rise together. Here breadth was very low. The other 495 stocks added only 7% in total.

The market has been up and down. The S&P 500 closed at 7,798.99 on Aug. 13, up 0.65% to a new record close, according to Reuters. Before that, it rose for nine weeks in a row, up 1.4% in four trading days, according to Investopedia. Between those gains, the Dow fell 953.33 points, or 1.9%, to 49,918.78, according to MarketWatch.

To put drops in context, a fall to 5,400 would be a 23% fall from its recent high, according to MarketWatch. A 20% fall is commonly called a bear market.

The broader context here is what this narrow lead means for regular savers. When a few huge companies count so much, they can lift the whole index even when most stocks do little. Your index fund can go up while most companies inside it do not.

In my view, that makes risk harder to see. When five stocks drive 93% of the gain since late July, bad news for one of them can drag the whole index down. You may feel spread across 500 stocks, but your result still hinges on a few.

Looking at what this means for your money, the choice is tricky. Staying close to the index rides the winners higher but also lower if they drop. Avoiding those leaders helps if they fall but hurts if they keep rising. General safety steps help with a broad drop, not with a case where leaders stall and the rest stays flat.

When it comes to trading, crowding can make moves sharper. When many investors bet the same way and follow short-term trends, calm gains can turn into fast losses as everyone adjusts at once. Things can look steady until selling in those few leaders forces prices down quickly.

Stepping back, this does not tell us what happens next. A narrow rally can keep going if those big companies keep earning more. For gains to continue, those five must keep carrying the load. A healthier rally would need the other 495 to help, and that has not happened since late July.