The S&P 500 is down.

But most of that weakness has come from the same handful of stocks that led on the way up.

The Mag 7 have done the heavy lifting on the downside. The other 493 have had far less impact.

That is the risk with a concentrated market.

When leadership narrows too much, index performance can start to say more about a few mega-caps than the market itself.

Now the key question is:

is this healthy rotation beneath the surface - or the start of something bigger?