SPY vs VO: how much do they really overlap?
SPY (SPDR S&P 500 ETF Trust, tracking the S&P 500) and VO (Vanguard Mid-Cap ETF, tracking the CRSP US Mid Cap) overlap by roughly 0% by weight. 0 of SPY's top 10 holdings also appear in VO. A 50/50 blend of the two behaves like about 191 equally-weighted bets (diversification grade A). In short, the two funds hold almost none of the same securities — they are complementary, not redundant.
The same companies, in both funds
These 0 holdings appear in both SPY and VO. The weight columns show how much of each fund each name represents.
| Holding | in SPY | in VO |
|---|
Only in SPY
SPDR S&P 500 ETF Trust — US large-cap. Its biggest holdings that VO doesn’t have:
| NVDA NVIDIA Corporation | 7.38% |
| AAPL Apple Inc. | 6.47% |
| MSFT Microsoft Corporation | 4.28% |
| AMZN Amazon.com, Inc. | 3.68% |
| GOOGL Alphabet Inc. | 3.24% |
| AVGO Broadcom Inc. | 2.76% |
| GOOG Alphabet Inc. | 2.60% |
| MU Micron Technology, Inc. | 2.02% |
Only in VO
Vanguard Mid-Cap ETF — US mid-cap. Its biggest holdings that SPY doesn’t have:
| STX Seagate Technology Holdings plc | 1.90% |
| WDC Western Digital Corp. | 1.78% |
| VRT Vertiv Holdings Co. Class A | 1.18% |
| PWR Quanta Services Inc. | 1.06% |
| HWM Howmet Aerospace Inc. | 1.03% |
| MRVL Marvell Technology Inc. | 0.89% |
| CMI Cummins Inc. | 0.89% |
| CEG Constellation Energy Corp. | 0.88% |
So — essentially different. Should you hold both?
SPY and VO hold almost none of the same securities — they are complementary, not redundant. Held together they genuinely broaden your exposure — a 50/50 blend reaches ~191 effective positions (grade A), because they hold largely different securities.
Holdings as of — SPY: Jun 29, 2026 (State Street Global Advisors); VO: May 31, 2026 (Vanguard). Refreshed monthly. Overlap is measured across each fund’s largest holdings (top 50); the diffuse long tail barely moves the math.
See this for YOUR whole portfolio, free →SPY vs VO — FAQ
- How much do SPY and VO overlap?
- SPY and VO overlap by approximately 0% measured by portfolio weight — that is the share of the smaller fund's holdings (by weight) that also sit inside the other. 0 of SPY's 10 largest holdings are also held by VO. They share 0 of their listed top holdings in total.
- Is it redundant to hold both SPY and VO?
- Because they hold almost none of the same securities — they are complementary, not redundant, holding both is not redundant — each fund covers largely different holdings, so together they broaden your exposure. A 50/50 blend has an effective 191 positions and a A diversification grade.
- What does VO hold that SPY doesn't?
- VO's largest holdings that SPY doesn't hold include STX, WDC, VRT, PWR, HWM. Its category is US mid-cap, versus SPY's US large-cap.
- Which is more concentrated, SPY or VO?
- SPY's top 10 holdings are 71% of its listed weight; VO's are 31%. The more concentrated fund leans harder on its largest names.