Is My Portfolio Diversified Enough? 4 Tests to Run
Owning many tickers is not the same as owning many bets. Four quick tests, with rule-of-thumb thresholds, show whether your portfolio is really diversified and balanced.
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ETF Overlap: VOO vs QQQ, VTI, VGT, SCHD and VYM
How much do the most popular ETF pairs overlap? Overlap by weight for VOO and QQQ, VOO and VTI, QQQ and VGT, and SCHD and VYM, how each pair moved, and what owning both does.
Key takeaways
- By weight, VOO and VTI overlap about 88%, VOO and QQQ about 54%, QQQ and VGT about 50%, and SCHD and VYM about 21% (ETF Research Center, read Oct 12, 2026).
- Owning VOO and QQQ is not wrong, but it is a deliberate tilt to large tech, not extra diversification: the two had a 0.92 correlation over five years (Exent’s data).
- VTI holds about 3,000 more stocks than VOO, mostly mid and small companies, yet tracked the S&P 500 closely: its correlation with SPY was 1.00.
- Low holdings overlap does not mean different behavior. SCHD and VYM share only 21% by weight, but both fell about 18–19% in 2022.
In this article
How much do popular ETF pairs overlap?
Overlap by weight is the share of one fund’s money that sits in the same stocks as the other. For each shared stock you take the smaller of its two weights, then add them up. Figures below are from ETF Research Center’s overlap pages, read on Oct 12, 2026. Fund holdings change, so treat them as a snapshot.
| Pair | Overlap by weight | Shared holdings | Holdings in each fund | Correlation (60 months) |
|---|---|---|---|---|
| VOO and VTI | 88% | 494 | 509 and 3,517 | 1.00 (VTI vs SPY) |
| QQQ and VUG | 58% | 53 | 103 and 151 | 0.98 |
| VOO and QQQ | 54% | 85 | 509 and 103 | 0.92 |
| QQQ and VGT | 50% | 35 | 103 and 322 | 0.97 |
| SCHD and VYM | 21% | 78 | 102 and 612 | Not computed |
| VOO and SCHD | 8% | 44 | 509 and 102 | 0.71 (SCHD vs SPY) |
- VOO and VTI
- Overlap by weight
- 88%
- Shared holdings
- 494
- Holdings in each fund
- 509 and 3,517
- Correlation (60 months)
- 1.00 (VTI vs SPY)
- QQQ and VUG
- Overlap by weight
- 58%
- Shared holdings
- 53
- Holdings in each fund
- 103 and 151
- Correlation (60 months)
- 0.98
- VOO and QQQ
- Overlap by weight
- 54%
- Shared holdings
- 85
- Holdings in each fund
- 509 and 103
- Correlation (60 months)
- 0.92
- QQQ and VGT
- Overlap by weight
- 50%
- Shared holdings
- 35
- Holdings in each fund
- 103 and 322
- Correlation (60 months)
- 0.97
- SCHD and VYM
- Overlap by weight
- 21%
- Shared holdings
- 78
- Holdings in each fund
- 102 and 612
- Correlation (60 months)
- Not computed
- VOO and SCHD
- Overlap by weight
- 8%
- Shared holdings
- 44
- Holdings in each fund
- 509 and 102
- Correlation (60 months)
- 0.71 (SCHD vs SPY)
Is it bad to own both VOO and QQQ?
Not bad, but it is a tilt, not diversification. About 54% of the two funds’ weight is the same stocks, and the shared names are the largest US companies. Adding QQQ to VOO raises your weight in mega‑cap tech and growth. That raised both the return and the risk over the past decade:
| Exent’s data, as of Sep 30, 2026 | VOO (S&P 500) | QQQ (Nasdaq-100) |
|---|---|---|
| 10-year annual return | 15.2% | 20.9% |
| 5-year volatility | 16.8% | 22.3% |
| Fall in the 2022 bear market | −25.4% | −34.6% |
| Fall in the COVID crash, 2020 | −34.3% | −28.6% |
| Fall in the 2025 tariff selloff | −19.0% | −22.9% |
Past results, not a forecast. The pairing worked well when large growth stocks led and hurt more when they fell, as in 2022. If you hold both, decide the tech tilt on purpose and size QQQ for it. Your total exposure to the largest names is worked out in how much of my portfolio is in the Magnificent 7. Data pages: VOO and QQQ.
VOO vs VTI: do I need both? Does a total market fund overlap with an S&P 500 fund?
Usually not both. A total market fund contains the S&P 500 plus thousands of smaller companies, but it is weighted by market value, so the S&P 500 companies dominate it. ETF Research Center shows 88% overlap by weight between VOO and VTI, with 494 shared holdings; VOO lists 509 and VTI 3,517.
The extra 12% or so of VTI is mid and small companies. That slice changed little in practice. In the same data VTI’s correlation with SPY was 1.00, its 10‑year annual return 14.6% vs 15.2% for VOO, and its fall in 2022 was 26.2% vs 25.4%. Holding both mostly means holding the same thing twice. If you want more small‑ and mid‑cap exposure, a dedicated fund changes the mix far more than adding VTI to VOO. See VTI.
How much do QQQ and VGT overlap?
About 50% by weight, with 35 shared holdings. They are built differently. QQQ tracks the Nasdaq‑100, the largest non‑financial companies listed on the Nasdaq, which includes retail, media and consumer names. VGT holds only the information technology sector, so it leaves out companies classified elsewhere, such as Amazon, Alphabet and Meta, and adds many smaller tech companies.
In behavior they are close. In the same data the correlation was 0.97, and in 2022 QQQ fell 34.6% and VGT 34.8% from peak to trough. VGT was more volatile: 25.1% over five years against 22.3%. Holding both doubles down on one sector rather than spreading risk. More in too much tech exposure.
How much do SCHD and VYM overlap?
Less than people expect: about 21% by weight. Most of SCHD’s 102 stocks are also in VYM, but VYM holds 612 and weights them differently, so the shared money is small. The two follow different rules for picking dividend stocks.
| Data as of Sep 30, 2026 | SCHD | VYM |
|---|---|---|
| Correlation with the S&P 500 | 0.71 | 0.82 |
| 5-year volatility | 14.4% | 13.9% |
| Fall in the COVID crash, 2020 | −32.7% | −35.1% |
| Fall in the 2022 bear market | −18.9% | −17.5% |
| 10-year annual return | 12.3% | 11.2% |
Low holdings overlap, similar outcomes. Both are tilted to large value and dividend payers, and both fell less than the S&P 500 in 2022 and about as much in 2020. This is why overlap by holdings is only half the picture.
Holdings overlap vs moving together
There are two ways to measure overlap. Holdings overlap asks whether two funds own the same stocks; use issuer holdings lists or an overlap tool, as explained in ETF overlap. Return correlation asks whether two funds move together, whatever they hold. SCHD and VYM show why you need both: low holdings overlap, similar behavior.
The second method scales to a whole portfolio: group funds and stocks into clusters whose returns move together. For the weight method step by step, see the ETF overlap checker.
What to do if your ETFs overlap
- Decide what each fund is for. If two do the same job, one is usually enough.
- If you keep an overlapping pair on purpose, such as VOO plus QQQ for a tech tilt, size the tilt deliberately.
- Add up your exposure to the largest companies across all funds and direct stocks.
- Check how the funds moved together in past sell-offs, not only what they hold.
- Remember taxes and costs before selling a fund in a taxable account.
How Exent measures overlap
- Upload a screenshot of your holdings, or a CSV, Excel, PDF or Google Sheet; no brokerage login.
- Exent measures overlap by how holdings move (correlation), not by opening each fund’s holdings list.
- Crash replays show how clustered funds fell together in 2008, 2020 and 2022.
- Remove or resize a fund in the what‑if simulator to see the effect before you trade.
Frequently asked questions
Not bad, but about 54% of their weight is the same stocks, so QQQ adds a tilt to large tech and growth rather than diversification. In 2022 QQQ fell 34.6% and VOO 25.4% in Exent’s data.
Usually not. They overlap about 88% by weight and moved almost identically in Exent’s data. VTI adds smaller companies, but they are a small part of its weight.
Yes, heavily. All S&P 500 companies are inside a total market fund and make up most of its weight; ETF Research Center shows about 88% overlap for VOO and VTI.
About 50% by weight according to ETF Research Center, and in Exent’s data they had a 0.97 correlation. VGT holds only technology stocks; QQQ also holds companies like Amazon and Alphabet.
About 21% by weight, according to ETF Research Center. Despite that, both fell about 18 to 19 percent in the 2022 bear market in Exent’s data.
A common rule of thumb reads above 50% by weight as high, meaning the two funds largely duplicate each other. It is a rule of thumb, not an industry standard.
See which of your funds move as one.
Exent groups your ETFs and stocks into correlation clusters and shows how many unique positions you really hold.
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Educational content, not investment advice. Examples are illustrative; past performance does not guarantee future results.