ITOT vs VO: 16% overlap
iShares Core S&P Total U.S. Stock Market ETF and Vanguard Mid-Cap ETF share 16.2% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
You would hold two tickers and get the diversification of 1.8. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
ITOT and VO hold 281 of the same securities. The ten contributing most to the overlap figure:
| Holding | in ITOT | in VO | Δ |
|---|---|---|---|
| STX | 0.3% | 1.0% | 0.8% |
| WDC | 0.3% | 1.1% | 0.8% |
| CASH | 0.2% | 0.5% | 0.3% |
| VRT | 0.2% | 1.2% | 1.1% |
| HWM | 0.2% | 1.0% | 0.9% |
| NEM | 0.1% | 0.5% | 0.3% |
| PWR | 0.1% | 1.0% | 0.9% |
| FTNT | 0.1% | 0.5% | 0.3% |
| WMB | 0.1% | 0.4% | 0.3% |
| CMI | 0.1% | 1.0% | 0.8% |
Where ITOT and VO differ
Sector weights as a share of each fund, ordered by the size of the gap rather than the size of the sector — two funds that overlap heavily still usually diverge somewhere.
| Sector | ITOT | VO | Δ |
|---|---|---|---|
| Information Technology | 35.2% | 16.1% | +19.1pp |
| Industrials | 10.1% | 19.6% | −9.4pp |
| Utilities | 2.2% | 8.4% | −6.1pp |
| Communication Services | 8.7% | 2.8% | +6.0pp |
| Energy | 3.5% | 7.3% | −3.8pp |
| Real Estate | 2.3% | 5.1% | −2.8pp |
| Materials | 2.1% | 4.3% | −2.3pp |
| Health Care | 9.7% | 7.8% | +1.9pp |
Δ is ITOT minus VO, in percentage points. Sector data is not published by every issuer, so “Unclassified” is a real category rather than a gap in the table.
What each fund holds alone
83.8% of ITOT by weight, held in no part of VO.
0.4% of VO by weight, held in no part of ITOT.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| ITOT | VO | |
|---|---|---|
| Top 10 holdings | 32.7% | 9.5% |
| Positions held | 2,440 | 283 |
| Cost per $10,000 held, per year | $3 | $3 |
Cost is the expense ratio applied to $10,000; it excludes any brokerage commission, bid-ask spread or tax consequence. Figures are facts about the funds, not a suggestion about which to hold.
Frequently asked
How much do ITOT and VO overlap?
ITOT and VO overlap 16.2% by portfolio weight — moderate overlap. They share 281 holdings. The figure comes from current issuer holdings files (ITOT as of 2026-07-23, VO as of 2026-06-30).
How is the overlap between ITOT and VO calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If ITOT holds a stock at 6% and VO holds the same stock at 4%, 4% counts as shared. The result is bounded between 0% and 100%, and it is computed after looking through any fund-of-funds to the underlying holdings.
Is it redundant to hold both ITOT and VO?
That depends on your goals — we state facts, not advice. At 16.2% overlap, each fund still contributes meaningfully distinct exposure.
What does ITOT own that VO doesn't?
ITOT holds 2,440 positions and VO holds 283; 2,158 of ITOT's positions don't appear in VO at all, and they are 83.8% of ITOT by weight.
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Related comparisons
Sources: issuer holdings files, ITOT as of 2026-07-23, VO as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.