Strong A-D lines confirm S&P 1500 rally

Solid breadth market breadth remains a key theme across most of the important U.S. equity indices.

The broad-based S&P 1500 Index, which includes the S&P 500 (large caps), S&P 400 (mid caps), and S&P 600 (small caps), has reached new all-time highs into mid and late December. Market breadth as measured by the advance-decline (A-D) lines provided both a leading and confirming indicator for these new highs.

Volume leads price. The S&P 1500 volume A-D line broke out to a new high in early December. New highs for the volume A-D line provided a bullish leading indicator for new highs on the S&P 1500 into mid and late December, reinforcing the message that broad, volume-confirmed participation continues to underpin the uptrend. This is similar to the bullish setup when the volume A-D line reached a new high on May 12, 2025, which preceded new highs on the index in late June.

Chart 1: S&P 1500 (top) and S&P 1500 advance-decline volume line (bottom)

Solid breadth confirms the uptrend. The S&P 1500 A-D line shows solid market breadth with a push to new highs that have confirmed the new highs on the index in both early July and mid December.

Chart 2: S&P 1500 (top) and S&P 1500 advance-decline line (bottom)