History

In September 2010, S&P created an equal weighted commodity index [2]. S&P has also created equal weighted versions of the S&P MidCap 400 and S&P SmallCap 600 indices.

Characteristics

Asset weightings

In weighting securities, an equal weighted index will usually divide a security by the total number of securities in the index (1/n). Thus each stock in the popular S&P EWI comprises 1/500 or 0.20% of the index. In the S&P EWI, stocks 500 to approximately 125 (in market cap size) are moderately overweighted and stocks approximately 125 to 1 are progressively underweighted. The effect of equal weighting is to give smaller companies in a stock index more influence over index performance than would occur in a capitalization weighted index. There is also a tendency for equal weighting to give higher weighting to value stocks. Equal weighted indexes are also consistently less concentrated than market capitalization indexes. [2]

Sector weightings

The sector weightings in a broad market equal weighted stock index are not determined by the fluctuating size of the companies in the sector, but by the number of companies in the sector. The result is that the EWI has a more stable sector allocation in comparison to a corresponding market capitalization index. There is also a tendency for an EWI to over weigh sectors comprised of smaller stocks and under weigh sectors comprised of larger stocks [2]

Rebalancing and turnover

In order for an equal weighted index to maintain its equal weights it must be periodically rebalanced back to its target weightings. In the interim between rebalancing, security values will fluctuate away from equal weighting. The usual EWI rebalancing methodology dictates quarterly rebalancing of the index. These quarterly rebalancings result in an EWI having higher turnover rates in comparison with benchmark indices. During the 2004-2009 period, the S&P EWI 500 index had turnover averaging 28.1%. This compares to turnover rates of 2.8% for the S&P 500 index; 13.4% for the S&P MidCap 400 Index; and 13.1% for the S&P SmallCap 600 Index. [2]

Performance

The investment performance of an equal weight stock index will be affected by its greater holdings of smaller companies, any value tilt the weighting brings to the index, and the effects of quarterly rebalancing. S&P has back-tested results for the S&P EW 500 index going back to 1990 (the index was created in January, 2003.) Over the entire (1990 — 2009) period, the compounded annual return of equal weight 500 index outperformed the cap weight 500 index by +1.8%, but with considerable variance over market cycles. S&P reports that the EWI would have outperformed the S&P 500 in the early nineties; underperformed during the 1994 — 1999 period dominated by technology growth stocks; and outperformed over the 2000 — 2009 period. [2] The S&P EW index tends to have higher volatility than the S&P 500. Over the 2002 — 2007 period the annualized standard deviation was 10.97% for the S&P EWI versus 8.61% for the S&P 500. [5] Correlation of the S&P EW Index to the S&P 500 Index ranged from 84% to 98% (1990 — 2009), with the lowest correlations occurring during the 2000 — 2002 bear market. [2]

The following table provides annual returns for the S&P EWI.