VTI vs. VOO: Holdings, Overlap, and Basket Analysis

This is a holdings comparison, not a return forecast or a recommendation. The basket calculation uses Vanguard fund-series Form N-PORT positions dated June 30, 2026, filed under the SEC’s public reporting system. Vanguard’s VTI and VOO pages provide current objectives and fund details; those details can change after this snapshot. We separate the June 30 holdings from later profile statistics so different dates are not blended.

VTI is Vanguard’s Morningstar Total Stock Market ETF. Its current profile says it seeks to track the Morningstar US Total Market Index and uses index sampling. VOO seeks to track the S&P 500 Index and uses full replication. Vanguard listed a 0.03% expense ratio for each as of April 28, 2026. The matching fee does not make their baskets interchangeable: an index, its rules, and the portfolio built to follow it determine the exposure. See the VTI fund profile and VOO fund profile.

The Morningstar US Total Market Index aims to represent nearly the full investable U.S. stock market across large, mid, small, and micro companies. VTI samples that broad universe; it does not promise one share of every listed company. The S&P 500 instead selects 500 leading U.S. companies under eligibility rules and committee review. S&P describes the index as float-adjusted market-cap weighted and covering about 80% of available U.S. market capitalization. A company’s size and public float affect its weight, so both indexes are weighted toward their largest constituents. Read the S&P U.S. index methodology for the construction rules. For the approximate market-coverage figure, see the S&P 500 index overview.

The SEC filings let us compare reported weights on the same date. Each Alphabet share class is a separate security line, so GOOGL and GOOG appear separately. The top ten summed to 32.03% of VTI’s net assets and 36.40% of VOO’s. The recurring names are familiar; the meaningful difference is how much of each fund they occupy. These are fund-series portfolio positions shared by the fund’s share classes, not a claim that one ETF share unit directly owns the company. Top-ten totals use the unrounded filing weights; displayed rows are rounded to two decimals and may not sum exactly.

I kept equity holdings only, grouped duplicate lines by CUSIP, then matched the two June 30 filings by CUSIP. VTI had 3,497 distinct equity CUSIPs, VOO had 505, and 503 identifiers appeared in both. Summing the SEC-reported position percentages for those shared identifiers gives 88.09% of VTI net assets and 99.61% of VOO net assets. Equity positions overall were 99.78% and 99.75% of the funds, respectively. The remaining non-overlapping equity weights were 11.69% for VTI and 0.14% for VOO; the small remainder also includes non-equity assets. See the VTI filing and VOO filing.

Suppose an investor holds $10,000 of VTI and $10,000 of VOO using the June 30 weights. NVIDIA represented about 6.36% of VTI and 7.51% of VOO, so the positions imply about $636 and $751 of NVIDIA exposure. Together that is roughly $1,387, or 6.93% of the $20,000 ETF portfolio, before price changes and expenses. The second fund did not add a new asset class here; it raised the weight of a security already inside VTI. Other shared large holdings move in the same direction.

When you combine the funds, weight each holding by the dollars allocated to each ETF, not by its constituent count. If p is VOO’s share of the total ETF investment, a shared stock’s blended weight is (1−p) × its VTI weight + p × its VOO weight. An equal-dollar split gives NVIDIA about 6.93% and the top ten about 34.22%, using unrounded filing weights. A 75% VTI / 25% VOO split puts NVIDIA near 6.65%. These are dollar-weighted exposures, not return or whole-account risk forecasts; prices and rebalancing change them.

VTI’s larger security count expands the basket, but market-cap weighting makes the smallest positions contribute very little individually. Its broad reach can reduce dependence on an S&P 500 membership decision and add mid- and small-cap exposure, yet it does not turn the fund into an equal-weight portfolio. VOO’s 36.40% top-ten weight versus VTI’s 32.03% is one snapshot of the stronger mega-cap concentration. Neither holding count nor one concentration measure alone tells you which fund will perform better or lose less.

SPY and IVV also seek to track the S&P 500, so their core stock exposure is closely related to VOO. IVV’s current expense ratio is 0.03%; SPY’s is 0.0945% on State Street’s current profile. Fees are only one difference: fund structure, spreads, trading liquidity, taxes, and account features may matter too. Adding VOO beside SPY or IVV generally repeats much of the same index exposure. Compare the fund documents rather than treating several S&P 500 tickers as separate diversification. See the current issuer pages for IVV and SPY.

VTI alone is the broader U.S. basket; VOO alone concentrates on S&P 500 companies. Holding both can be an intentional large-cap tilt, but the overlapping positions mean the second ticker adds much less company breadth than its name might suggest. Before combining funds, total the dollars or weights in common holdings, then check foreign stocks, bonds, cash needs, fund expenses, and trading costs elsewhere in the portfolio. Holdings and index membership change, and the June 30 overlap is a dated snapshot—not a permanent ratio or a performance guarantee. For related mechanics, see ETF expense ratio versus total cost, tracking difference versus tracking error, and ETF NAV versus market price.