More S&P 500 stocks outperform benchmark in strongest breadth in a decade, Balchunas says

Market breadth in the S&P 500 improved materially in 2026, with 57% of constituents outperforming the benchmark, the strongest breadth reading in a decade, according to Bloomberg’s Eric Balchunas using Bloomberg Intelligence data. The note suggests the rally has broadened beyond a narrow group of mega-cap leaders, which is typically a constructive sign for the durability of the index advance. For equity investors, stronger participation across the index can reduce concentration risk and support a healthier market backdrop even amid mixed headlines during the year. The article does not indicate a specific catalyst for the breadth improvement, but frames it as a notable positive for U.S. large-cap equities.