The index headline hides what's actually happening beneath.

S&P 500 barely down this month, yet eight of eleven sectors are green. Health care, financials, energy, staples—all carrying weight.

But tech is bleeding 2%. Communication services another 0.7%. Together, they've dragged the whole thing down nearly 3 percentage points.

This is what concentration risk looks like in real time. A handful of names can mask—or sink—the broader picture. The market isn't weak. It's lopsided.

When leadership narrows, pay attention. It's often the prelude to something bigger.