Introduction
In today’s rapidly evolving equity market landscape, mega-cap stocks are not only influential—but they have become a defining force shaping performance and strategic direction. Over the past few years, the largest companies in the S&P 500® have reached notably elevated levels of market dominance. Exhibit 1 shows that the cumulative weights of the largest 5, 10 and 20 companies have reached their highest points since 1970, underscoring their significant impact on market dynamics.
Recognizing this trend, market participants have adopted varied strategies; some are targeting mega caps, whereas others are seeking diversification. S&P DJI has also introduced additional mega-cap indices in recent years, expanding the existing suite to provide benchmarks for those looking into these heavyweight market leaders.
This paper aims to dive deep into the following areas to highlight key trends and insights.
- Index construction of S&P DJI mega-cap indices: We outline the methodology behind the index construction, and we examine sector weighting and foreign revenue exposure of these indices.
- Historical and relative performance: Analyzing S&P DJI mega-cap indices’ historical risk/performance characteristics and comparing their relative performance to counterparts.
- Strategies for outperformance and diversification: Finally, we will highlight how equal weight or other barbell strategies could outperform a mega-cap index or help achieve diversification.
