By Jared Blikre

The S&P 500 (^GSPC) just broke out to new highs. The next question is whether it holds.

Thursday’s Chart of the Day looked at the index’s rare 10% surge in 11 trading days. The setup is historically bullish, but this version comes with a catch: The S&P 500 is already back near the highs. That makes the next confirmation test less about speed and more about participation.

The best tell may be breadth.

One way to track that is the advance-decline line, a running measure of how many S&P 500 stocks are rising versus falling. The so-called A-D line is cumulative, but the idea is simple: In a healthy breakout, you want lots of stocks rising with the index, not just a few big stocks doing most of the lifting.

The S&P 500 just broke out to fresh record highs. Its advance-decline line — a running total of how many stocks are going up versus down — has yet to confirm.

After last year’s "Liberation Day" sell-off, breadth confirmed the recovery early. The advance-decline line peaked first in late 2024 — marked (1) on the chart — then broke to a new high on May 2, 2025 (3). Only after that did the S&P 500 clear its own prior closing high on June 27, 2025 (4), after first peaking on Feb. 19, 2025 (2).

Today, the sequence is a little different. The S&P 500 peaked on Jan. 27, 2026 (5). Breadth peaked a month later, on Feb. 27 (6). Price has already broken out to a new closing high as of April 15 (7), but the advance-decline line has not yet confirmed with a breakout of its own.

The underlying numbers help explain why. Over the last 12 sessions, the average S&P 500 stock was up on a little more than seven of them. Fewer than half of index members were up on at least eight of the 12, and only about 20% were up on at least nine.

Under the hood, leadership has been strongest in technology, financials, and parts of the services complex. Energy has been the clear laggard, with consumer staples and utilities also trailing.

The setup still leans bullish. But for this breakout to look durable — and less like a failed push near the highs — breadth still needs to catch up.

Jared Blikre is the global markets and data editor for Yahoo Finance. Follow him on X at @SPYJared or email him at jaredblikre@yahooinc.com.