The concentration risk posed by mega-cap technology companies within the traditional S&P 500 index has drawn significant attention from investors. As a result, alternative indexing approaches have gained popularity, including low-volatility and dividend strategies. One such method attracting focus is equal weighting, exemplified by the Invesco S&P 500 Equal Weight ETF (RSP). This approach proposes an alternative to market-capitalization weightings by ensuring that every stock within the S&P 500 receives a uniform allocation of approximately 0.2%. The portfolio structure is maintained through quarterly rebalancing.
Mechanism and Sectoral Differences
While both RSP and the SPDR S&P 500 ETF Trust (SPY) hold shares in the same 500 companies, their resulting portfolios differ significantly at the sector level. Unlike market-cap weighting which allows the largest firms to dictate asset allocation, equal weighting diversifies exposure by giving all stocks an equal weight.
Compared to the conventional S&P 500 index, RSP shows increased allocations in several sectors: industrials (overweight by about 7%), real estate (by 4%), utilities (by 3.3%), materials (by 3%), financials (by 2.6%), healthcare (by 2%), consumer staples (by 1.8%), and energy (by 0.4%). Conversely, the ETF is underweight in communication services by 6.5% and information technology by a substantial 18.4%, and slightly underweights consumer discretionary by 0.2%.
These structural differences also impact key portfolio metrics. According to Invesco data, RSP’s average holding has a market capitalization of approximately $138 billion, compared to roughly $152 billion for SPY. Furthermore, RSP trades at a forward price-to-earnings ratio of 21.07, slightly lower than SPY’s ratio of 22.43.
Performance and Risk Analysis Over Two Decades
An examination of performance data spanning the period from April 2003 through July 2026 reveals measurable differences between the two strategies. Over this 23-year timeframe, SPY generated an annualized total return of 11.47%, resulting in a cumulative return of 1,145.58%. RSP slightly trailed this performance, achieving an annual return of 11.25% with a corresponding cumulative return of 1,089.36%.
When assessing risk, data suggests that the assumption that equal weighting inherently lowers volatility may be inaccurate. In fact, over the sample period, RSP recorded a higher annualized volatility at 19.80%, compared to SPY’s 18.52%. This difference was reflected in risk-adjusted returns; RSP produced a Sharpe ratio of 0.55, while SPY achieved a slightly stronger ratio of 0.59.
Costs and Operational Drawbacks
Beyond performance metrics, the operational costs associated with equal weighting must be considered. The Invesco S&P 500 Equal Weight ETF (RSP) charges an expense ratio of 0.20%, which is roughly double the fee charged by SPY.
Critics point out that the core mechanism of equal weighting involves fundamental trade-offs. Because the portfolio must be rebalanced quarterly, it requires selling recent high performers and purchasing underperforming assets, regardless of the underlying reasons for price movement. This process means the strategy is fundamentally arbitrary. As Peter Lynch famously noted, this effectively translates to “trimming the flowers and watering the weeds.”
While investors may favor equal weighting if they are uncomfortable with the current high concentration in technology stocks, analysts suggest that while behavioral advantages can be valuable, they do not negate the structural drawbacks. The constant turnover inherent in maintaining these equal weights requires careful scrutiny of its economic logic.
