RSP is a US ETF holding approximately 500 S&P 500 constituents with equal weights. Quarterly rebalancing resets each company to roughly 0.2%. It uses the same stock universe as the capitalization-weighted S&P 500 but reduces mega-cap influence and increases the role of smaller constituents. Equal stock weights do not mean equal sector weights: the number of constituents in each sector determines its allocation. Comparing the two weighting approaches highlights broad participation versus concentrated leadership.
History and development
RSP launched in 2003 to package equal-weight exposure to S&P 500 constituents in an ETF. As capitalization-weighted index products expanded, it offered an alternative that gives each company a similar starting weight rather than allocating by size. Its universe remains the S&P 500, not a small-cap index.
Daily price changes cause equal weights to drift. Quarterly rebalancing trims relative winners and adds to relative laggards to restore the allocation. This process reduces mega-cap concentration and creates a different long-term return pattern despite holding the same large-cap stock universe.
References: Invesco: RSP fund overview
Comparing charts on this board
Compare RSP with the S&P 500 to distinguish mega-cap leadership from broader participation. Stronger capitalization-weighted performance directs attention to the largest companies; stronger RSP performance highlights the relative strength of other constituents. The spread between weighting methods is a breadth signal, not proof that every constituent rose.
Add MAGS and the Nasdaq-100 to contrast mega-cap growth, the broad large-cap universe and equal-weight exposure. A rally confined to MAGS differs from one that reaches RSP. Compare percentage changes over matching reference periods rather than nominal price levels.
Related charts: S&P 500 · MAGS · NASDAQ 100 · VTI
Official references: Invesco: RSP fund overview