Key Morningstar Metrics for iShares Core S&P US Total Market Index ETF
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IShares Core S&P Total Market XUU accurately represents the US stock market, allowing its low fee and efficient portfolio to carve out a long-term edge.
The fund tracks the S&P Total Market Index, which selects all investable US stocks and weights them by market cap. As a result, the index experiences little turnover, thanks to the minuscule average size of additions or deletions to the portfolio. The fund holds a representative basket of stocks within the index, which further reduces unnecessary trading costs.
Assigning position sizes based on a stock’s market cap is a simple and efficient method to weight the portfolio. Since US stocks are highly traded, they quickly reflect new information, and carving an edge is difficult. Market-cap weighting naturally adjusts to price changes without frequent rebalancing, lowering trading costs. That and lower fees give large-blend index funds a long-term performance advantage over most actively managed peers.
The portfolio is broad and well-diversified. It typically holds around 2,500 stocks, and the top 10 represented 34% of the portfolio as of January 2026. Still, market-cap weighting can contribute to portfolio concentration when a few stocks dominate the market. This has been the case lately with a handful of mega-cap technology stocks growing to prominence and commanding a greater share of the portfolio.
When a few richly valued companies or sectors power most of the market’s gains, market-cap weighting may overexpose the strategy to the fluctuations of one stock or sector. But this is not a fault in design, as it simply reflects the market’s composition. The fund’s low turnover, low fee, and broad diversification across the US market more than offset these risks.
The US exchange-traded fund share class returned 15.1% annualized over the past 10 years through January 2026. It holds little cash, which should help it outperform cash-saddled active peers during market rallies. Likewise, low cash drag could hurt this fund when the stock market declines, but long-term positive results for the US market have given this efficient approach an edge. Performance across share classes will vary owing to differences in fees and currency exchange rates for non-US investors.
iShares Core S&P US Total Market Index ETF: Performance Highlights
The S&P Total Market Index returned 15.1% annualized over the past 10 years through January 2026. The iShares funds following this strategy vary in fees, influencing relative returns. However, fees across the board tend to be low, allowing them to capture nearly all of the index’s performance. Currency performance across the regions where the fund is offered can also drive relative returns. Additionally, most funds in the strategy engage in securities lending, which allows them to earn back a portion of their fees, slightly improving investor returns.
The strategy’s performance closely follows the ups and downs of the US stock market, since it is always fully invested. All else equal, this strategy should outperform Morningstar Category peers that hold cash during market rallies, holding back returns. But no cash buffer also means that the strategy may lag similar peers when the market falls.
Market-cap weighting leans the portfolio toward the largest US stocks despite including small-cap stocks. This means it will perform best when large stocks soar. The market’s largest stocks, like Nvidia, have dominated index returns. However, if mid- or small-cap stocks outperform, the fund should beat peers that exclude those segments.
Investors should expect meaningful fluctuations in performance over shorter periods because of the index’s dependence on the market’s largest companies. In its roughly 20-year history, the index has registered a negative annual return about 15% of the time. However, this is still less often than its average US large-blend category peer.
For non-US investors, iShares offers traditional or currency-hedged funds that replicate this strategy. While hedged funds mitigate currency risk, the cost of hedging can erode returns. Unhedged funds are exposed to currency fluctuations, but the impact of foreign-exchange rates on total return tends to wash out in the long term.
