SPY vs VO: 17% overlap
SPDR S&P 500 ETF Trust and Vanguard Mid-Cap ETF share 16.7% 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
SPY and VO hold 248 of the same securities. The ten contributing most to the overlap figure:
| Holding | in SPY | in VO | Δ |
|---|---|---|---|
| STX | 0.3% | 1.0% | 0.7% |
| WDC | 0.3% | 1.1% | 0.8% |
| VRT | 0.2% | 1.2% | 1.0% |
| HWM | 0.2% | 1.0% | 0.9% |
| NEM | 0.2% | 0.5% | 0.3% |
| PWR | 0.2% | 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% |
| MPC | 0.1% | 0.7% | 0.6% |
Where SPY 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 | SPY | VO | Δ |
|---|---|---|---|
| Information Technology | 37.5% | 16.1% | +21.4pp |
| Industrials | 8.9% | 19.6% | −10.7pp |
| Communication Services | 9.3% | 2.8% | +6.5pp |
| Utilities | 2.3% | 8.4% | −6.1pp |
| Energy | 3.4% | 7.3% | −3.9pp |
| Real Estate | 1.9% | 5.1% | −3.2pp |
| Materials | 1.8% | 4.3% | −2.5pp |
| Financials | 12.4% | 14.0% | −1.7pp |
Δ is SPY 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
83.3% of SPY by weight, held in no part of VO.
9.0% of VO by weight, held in no part of SPY.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| SPY | VO | |
|---|---|---|
| Top 10 holdings | 36.9% | 9.5% |
| Positions held | 505 | 283 |
| Cost per $10,000 held, per year | $9 | $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 SPY and VO overlap?
SPY and VO overlap 16.7% by portfolio weight — moderate overlap. They share 248 holdings. The figure comes from current issuer holdings files (SPY as of 2026-07-23, VO as of 2026-06-30).
How is the overlap between SPY and VO calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If SPY 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 SPY and VO?
That depends on your goals — we state facts, not advice. At 16.7% overlap, each fund still contributes meaningfully distinct exposure.
What does SPY own that VO doesn't?
SPY holds 505 positions and VO holds 283; 256 of SPY's positions don't appear in VO at all, and they are 83.3% of SPY by weight.
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Related comparisons
Sources: issuer holdings files, SPY as of 2026-07-23, VO as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.