The S&P 500 Turns Red. It's on Track for Worst Intraday Reversal in Nearly a Year.

The S&P 500 flipped red Monday, giving back a 1.1% intraday gain to trade down 0.1% and putting the index on track for its worst intraday reversal in nearly a year, per Barron's.

The Nasdaq Composite followed the same path, erasing gains after spending most of the session in positive territory. The morning's AI-driven rebound fizzled, and buyers who stepped in early found no follow-through. The Dow Jones Industrial Average held onto a gain but slipped well off its session highs, so even the index that stayed green lost ground from the peak.

The size of the swing matters here. A move from +1.1% to -0.1% is a 1.2-point round trip in a single session. If the S&P 500 closes in the red, it would confirm the reversal rather than a late-day wobble, and the pattern would mark the weakest intraday finish the index has posted in almost a year.

Interpretation: the failed rebound suggests that buyers lack conviction at higher levels, particularly in the AI-linked areas that drove the morning bid. The Dow's relative resilience points to a divergence between the broader price-weighted benchmark and the tech-heavy Nasdaq, though that reading rests on a single session.