Many sector ETFs appear diversified but are heavily weighted toward just a few large companies, exposing investors to concentration risk that may not match their expectations for broad sector exposure
Sector ETFs are often marketed as a way for investors to gain targeted exposure to specific industries without the need to pick individual stocks. Yet, the reality for most market-cap-weighted sector ETFs is that a handful of dominant companies drive the majority of returns and risk. This concentration can leave investors with portfolios that are far less diversified than they might assume, especially when the largest holdings account for a significant share of the fund's assets.
While the S&P 500's top-heavy nature is widely discussed, the issue is even more pronounced in many sector ETFs. Investors may believe they are spreading their bets across dozens of companies, but in practice, the largest names often overshadow the rest. This dynamic is particularly relevant for those seeking to manage risk or avoid overexposure to a single company or theme.
Concentration in Major Sector ETFs
Data from State Street's Select Sector SPDR ETFs highlights just how concentrated these funds can be. For example, the Consumer Discretionary Select Sector SPDR ETF (XLY) allocates nearly 45% of its portfolio to just three companies: Amazon, Tesla, and Home Depot. In fact, Amazon and Tesla alone make up about 40% of the fund. The Communication Services Select Sector SPDR ETF (XLC) is similarly concentrated, with Alphabet and Meta Platforms accounting for the bulk of its top-three holdings, while AT&T represents a much smaller portion. The Energy Select Sector SPDR ETF (XLE) is dominated by ExxonMobil and Chevron, which together comprise 35% of the fund's assets.
Even in the Technology Select Sector SPDR ETF (XLK), which is sometimes viewed as more diversified, Nvidia, Apple, and Microsoft collectively represent over a third of the portfolio. Adding Broadcom to the mix brings the concentration close to 40%. This pattern repeats across most sector ETFs, with the top three holdings often making up between 25% and 45% of the total assets, according to reporting by Financial Sumo.
Implications for Investors
For investors, this concentration means that sector ETFs may not provide the broad industry exposure they expect. Instead, performance is often tied closely to the fortunes of a few mega-cap stocks. If one of these companies underperforms or faces regulatory, competitive, or operational challenges, the entire ETF can be affected disproportionately. This risk is especially relevant in sectors where a small number of companies dominate market capitalization, such as technology, consumer discretionary, and energy.
Expense ratios for sector ETFs are typically low, with many major funds charging between 0.10% and 0.15% annually. However, the low cost does not offset the potential for concentrated risk. Investors should review the fund's holdings and weightings before assuming they are getting diversified exposure. For those seeking a more balanced approach, some providers offer equal-weighted sector ETFs, which distribute assets more evenly across all constituents and reduce the influence of the largest companies.
Alternatives and Portfolio Construction
Investors looking to avoid concentration risk may consider equal-weighted sector ETFs, which assign the same weight to each company in the index. This approach can help mitigate the outsized impact of mega-cap stocks and provide a truer representation of sector performance. However, equal-weighted funds may have higher turnover and slightly higher fees, and their returns can diverge significantly from traditional market-cap-weighted funds, especially during periods when large-cap stocks outperform.
For those interested in how ETF structure and sector exposure can affect long-term returns, the article on differences between growth ETFs provides additional context on how fund composition shapes risk and reward. Ultimately, understanding the underlying mechanics of sector ETFs is essential for building a portfolio that matches your risk tolerance and investment goals.
Sector ETFs are a popular tool for investors seeking targeted exposure, but their structure can create hidden risks. Market-cap weighting means that a few large companies often dominate returns, reducing the diversification benefit many investors expect. Reviewing fund holdings, considering alternative weighting schemes, and understanding the trade-offs between concentration and diversification are key steps for anyone using sector ETFs as part of their investment strategy.
