DIA vs VO: how much do they really overlap?
DIA (SPDR Dow Jones Industrial Average ETF, tracking the Dow Jones Industrial Average) and VO (Vanguard Mid-Cap ETF, tracking the CRSP US Mid Cap) overlap by roughly 0% by weight. 0 of DIA's top 10 holdings also appear in VO. A 50/50 blend of the two behaves like about 73 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 DIA and VO. The weight columns show how much of each fund each name represents.
| Holding | in DIA | in VO |
|---|
Only in DIA
SPDR Dow Jones Industrial Average ETF — US blue-chip (Dow 30). Its biggest holdings that VO doesn’t have:
| CAT Caterpillar Inc. | 11.76% |
| GS The Goldman Sachs Group, Inc. | 11.61% |
| UNH UnitedHealth Group Incorporated | 4.78% |
| MSFT Microsoft Corporation | 4.20% |
| AMGN Amgen Inc. | 4.10% |
| GOOGL Alphabet Inc. | 4.03% |
| HD The Home Depot, Inc. | 3.99% |
| SHW The Sherwin-Williams Company | 3.92% |
Only in VO
Vanguard Mid-Cap ETF — US mid-cap. Its biggest holdings that DIA 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?
DIA 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 ~73 effective positions (grade A), because they hold largely different securities.
Holdings as of — DIA: 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 →DIA vs VO — FAQ
- How much do DIA and VO overlap?
- DIA 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 DIA'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 DIA 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 73 positions and a A diversification grade.
- What does VO hold that DIA doesn't?
- VO's largest holdings that DIA doesn't hold include STX, WDC, VRT, PWR, HWM. Its category is US mid-cap, versus DIA's US blue-chip (Dow 30).
- Which is more concentrated, DIA or VO?
- DIA's top 10 holdings are 59% of its listed weight; VO's are 31%. The more concentrated fund leans harder on its largest names.