Asset Allocation Bi-Weekly – The Cap-Weighted & Equal-Weighted S&P 500

There are many ways to describe the strong performance in large cap US stock prices this year. You could simply call it a bull market, with the S&P 500 total return index up 31.2% since its low in early April and up 11.5% year-to-date. The strong buying pressure could even be called a “euphoria.” With continued gains, it would be no surprise if some observers started referring to it as a return to the type of “irrational exuberance” seen in the 1990s. In any case, the market is exhibiting strong momentum, especially in the growthy sectors such as Information Technology and Communication Services. Indeed, investors now widely understand that the lion’s share of the uptrend this year has come from just a few stocks within those sectors, i.e., the Magnificent 7. A key question is whether these trends will continue. And to the extent that there is a risk of these trends reversing, is there a good way to hedge the associated downside risk?

The growth of index investing in recent decades is probably one reason for the outperformance of large cap growth stocks like the Mag 7. Many individual and institutional investors simply channel their US large cap stock investments into funds tracking the S&P 500 Index, where each holding is weighted by the stock’s total market capitalization. Funds channeled into this version of the S&P 500 go disproportionately to those stocks with big market caps, especially the Mag 7, helping them appreciate even more. But there is also a version of the S&P 500 in which the allocation to each stock is an equal 0.2% — the S&P 500 Equal Weight Index. In this methodology, stocks with smaller capitalizations and more “value” characteristics have a higher representation than they do in the capitalization-weighted version. If we compare the performance of the cap-weighted S&P 500 to that of its equal-weighted counterpart, we can get a sense of the relative advantages or disadvantages of each index during different market scenarios.

In the upper panel of the following chart, we show the S&P 500’s total return index in both its cap-weighted and equal-weighted forms, with each based to 100 in January 1990. The figure shows that over the last 35 years, the equal-weighted variation of the S&P 500 has produced a meaningfully higher total return than the market cap-weighted one. (Consistent with finance theory, the higher return for the equal-weighted index also comes with a higher standard deviation.)