Quantum computing stocks index builder to weight the pure plays yourself and backtest against each quantum computing ETF
The largest quantum fund keeps about 12% of its money in quantum companies. Pick the names you mean, set each weight, and see how the basket would have done next to the S&P 500 and the funds. Then buy it at your own broker.
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In short
Quantum computing stocks are the listed companies whose main business is building quantum computers or the software and security around them, such as IonQ, Quantinuum, D-Wave and Rigetti. The ETFs sold as quantum funds hold very different amounts of them. The Defiance Quantum ETF (QTUM, 0.40%, $5.6 billion) had 11.8% in listed pure plays on September 30, 2026, WisdomTree's WQTM (0.45%) about 35%, Corgi's CQTM (0.35%) 78% and Defiance's QTUP (0.77%) nearly 100%. Building your own quantum computing stocks index means choosing that share and each weight yourself, backtesting the basket, and buying the stocks at a broker, where there is no expense ratio.
Summed from each fund's published holdings
How much of a quantum computing ETF is actually quantum?
Each bar is the share of one fund held in the fourteen US-listed companies whose main business is quantum computing or quantum security. Everything to the right of the red is something else.
Vanguard Information Technology (VGT)
0.19%
Aug 31. IonQ, Rigetti, D-Wave and Quantum Computing Inc together
Global X CHPX
0.57%
Sep 29 holdings file
Defiance QTUM
11.84%
Sep 30 holdings. The four best known pure plays are 3.67%
WisdomTree WQTM
35.18%
Aug 26, top ten only. 34.28% on the full June 30 filing
Amplify XQBT
44.97%
Aug 19 launch holdings
Corgi CQTM
78.29%
Sep 29 holdings
Defiance QTUP
99.8%
Sep 30, counting swap exposure
The spread runs from one fifth of one percent to nearly all of the fund, under the same word on the label. QTUM is the one most people buy, and the reason it is so diluted is in its index rule. The BlueStar index admits companies with at least half of their revenue or operating activity in quantum computing or machine learning, and it counts machine learning hardware, chip packaging machinery and raw materials. Then it weights every member equally. With 86 members, a quantum hardware maker gets about the same 1% to 2% as a cloud software company. On September 30 the four best known pure plays, IonQ, Rigetti, D-Wave and Quantum Computing Inc, added up to 3.67% of the fund.
That is a design choice with a logic to it: most of the fund is established technology companies, so it depends far less on a handful of young, loss-making ones. But if you bought it to own quantum computing, you own mostly something else. At the other end, QTUP holds eleven pure plays and nothing else, gets part of its exposure through swaps, and charges 0.77%. Neither end lets you pick the number in between. A basket of your own does.
From each issuer's fund page and SEC filings
Which quantum computing ETF holds what, and how does each one pick its stocks?
| Fund | Expense ratio | Stocks | Rule | Largest positions |
|---|---|---|---|---|
| Defiance Quantum (QTUM) | 0.40% | 86 | Index of companies with at least 50% of revenue or activity in quantum computing or machine learning, equal weighted, reset each June and December | Global Unichip 2.3%, Arqit 2.1%, Cloudflare 1.9%, Elastic 1.7%, Palantir 1.7% (Sep 30) |
| WisdomTree Quantum Computing (WQTM) | 0.45% | 46 | Index that tilts weight toward companies scored as pure and highly relevant, 15% cap per stock | IonQ 5.7%, Rigetti 5.5%, D-Wave 5.4%, IBM 5.2%, Quantum Computing Inc 5.0% (Aug 26) |
| Corgi Quantum Computing (CQTM) | 0.35% | 18 | Actively managed, no index. At least 80% in companies materially involved in quantum computing and quantum ready security | IonQ 17.8%, D-Wave 9.6%, Rigetti 7.6%, Quantinuum 7.5%, Infleqtion 5.8% (Sep 29) |
| Amplify Top 10 Quantum (XQBT) | 0.49% | 10 | Actively managed around a ten stock Bloomberg momentum index, reviewed quarterly. Launched August 2026 | Keysight 15.1%, IonQ 14.6%, Alphabet 10.9%, Amazon 10.3%, D-Wave 9.5% (Aug 19) |
| Defiance Long Pure Quantum (QTUP) | 0.77% | 11 | Actively managed, pure plays only, partly held through swaps. Launched June 2026 | IonQ 21.0%, Quantinuum 15.2%, D-Wave 14.7%, Infleqtion 9.2%, Arqit 8.5% (Sep 30) |
| Global X AI Semiconductor & Quantum (CHPX) | 0.50% | 38 | Float market cap index, 10% cap per stock. A chip fund with a small quantum sleeve | Micron 13.3%, TSMC 10.6%, NVIDIA 9.9%, Broadcom 8.0%, AMD 5.5% (Sep 29) |
Size and age differ as much as the holdings. QTUM has been trading since September 2018 and held $5.63 billion on September 29. WQTM launched in October 2025 and had $345 million in late August. The other three are months old and small: CQTM had $15.6 million, QTUP $19.5 million and XQBT $1.7 million. A fund that small can close, and its bid and ask can sit further apart than the fee suggests, so check both before you buy.
There are also leveraged and single stock products with quantum in the name, such as QPUX (twice the daily move of a pure play basket, 1.29%) and IONX (twice the daily move of IonQ, 1.38%). They reset every day and are built for short trades, so they are a different product from everything in this table. More funds are on the way as well: Roundhill and First Trust have both filed for quantum ETFs that were not yet trading when we checked. The fee side of the choice, ranked from cheapest, is in our comparison of Vanguard quantum computing ETF alternatives.
Fourteen listed pure plays, three tiers
Which stocks belong in a quantum computing stocks index?
Two years ago a pure quantum basket had four well known names in it. Quantinuum listed on Nasdaq in June 2026, and Infleqtion, Xanadu, IQM, Pasqal and Horizon Quantum arrived through mergers with listed shells, so there are now enough companies to build a real index with tiers.
1
Hardware makers above $3 billion
2
Smaller hardware and software names
3
Quantum security small caps
Market values are approximate, from the September 29, 2026 close, and they move a lot. The names are the listed universe, not a recommendation. Most of these companies report small revenue and large losses, and several have traded for less than a year. PsiQuantum, often mentioned beside them, is still private.
A fourth tier is optional and changes the character of the index: the large companies with serious quantum programs, such as IBM, Alphabet, Microsoft, Honeywell and NVIDIA. WQTM and XQBT both hold some of them. Adding a 30% to 50% sleeve of those names steadies the basket, at the cost of making it look more like the Nasdaq-100 you may already own. That trade is exactly what a backtest is for. Weighting is the other decision. By market value, IonQ and Quantinuum would be more than half of a pure play index; an equal weight index or a cap per stock spreads it out.
From a view on quantum to a basket you can buy
How to build your own quantum computing stocks index in four steps
1
Set the pure play share
Decide how much goes to pure quantum companies and how much to large companies with quantum programs, before you pick a stock.
2
Add the names and a cap
Search the catalog of US-listed stocks and ETFs, add 8 to 20 names, and choose equal weight, market cap weight or your own weights with a limit per stock.
3
Backtest against the funds
Run it against the S&P 500 and the Nasdaq-100, and build a one-line index of QTUM or WQTM to put the fund on the same chart.
4
Track it, then buy it
Follow the index daily against its benchmark, export the weights, and place the basket at your own broker when you are ready.
Be honest with the backtest, because this theme makes it easy to fool yourself. A basket can only be tested as far back as its youngest stock, and several of the pure plays listed in 2025 or 2026. A test that starts in 2024 with only the four older names will show a spectacular line that mostly reflects one rally. Look at the maximum drawdown beside the S&P 500 before you look at the return, and test more than one start date. Backtests are hypothetical and past returns do not predict future ones; use them to compare designs, not to forecast. Because these stocks move so much, weights drift quickly, so also test a quarterly reset with the custom index rebalancing tool.
Three ways to own quantum computing, compared honestly
Build your own quantum index vs a quantum computing ETF vs a basket broker
| Quantum computing ETF | Fidelity Basket Portfolios | Indexes, then your broker | |
|---|---|---|---|
| Who sets the pure play share | The fund's index or manager, from 0.6% to nearly 100% | You | You, and you can test it first |
| Yearly cost | 0.35% to 0.77% of the balance | $4.99 a month flat | From $24 a month for the software, plus your broker's cost |
| History you can test | Since launch, a year or less for five of the six | None | As far back as your youngest stock goes |
| Swaps and derivatives | Used by QTUP, allowed in XQBT | None, you own the shares | None, you own the shares |
| Per-stock tax losses | No | Yes, done by you | Yes, at your broker |
| Where it falls short | You take someone else's definition of quantum | No way to test a design before buying | You place and rebalance the trades |
The ETF wins when you want one ticker and no upkeep, and when a fund's mix already matches your view. QTUM is a reasonable broad technology fund with a quantum tilt, and CQTM is cheap for what it holds. Building your own wins once the balance is large enough that a flat $59.88 a year beats the fund's fee, roughly $7,800 against a 0.77% fund and $15,000 against a 0.40% fund, and whenever the pure play share you want sits between what the funds offer.
Owning the shares has a tax side that matters more here than in most themes. These stocks swing hard, so in any given year some positions will be down while others are up. Each one has its own cost basis, which means a loser can be sold for a tax loss while the rest of the basket stays in place; a fund only lets you sell the whole thing. Check the dates with the wash sale calculator before you buy the same name back.
What Indexes does and does not do: it is index construction, backtesting and tracking software. It does not hold money, place trades or give investment advice. You design and test the quantum computing stocks index here and hold it wherever you already invest.
Quantum computing ETF and stock questions
What people ask before they buy quantum computing stocks
What is the best ETF for quantum computing?
It depends on how much quantum you want in it. QTUM (0.40%, $5.6 billion) is the largest, but listed quantum pure plays are about 12% of it; the rest is chip, software and hardware companies. WQTM (0.45%) holds about 35% in pure plays. CQTM (0.35%) is the cheapest and about 78% pure plays, with $16 million in assets. QTUP (0.77%) holds only pure plays and uses swaps.
Is there a quantum computing index fund?
Yes. The Defiance Quantum ETF (QTUM) tracks the BlueStar Quantum Computing and Machine Learning Index and the WisdomTree Quantum Computing Fund (WQTM) tracks a WisdomTree index. Both are ETFs. There is no quantum computing index mutual fund from Vanguard, Fidelity or Schwab. The other US quantum funds, CQTM, XQBT and QTUP, are actively managed and do not track an index.
Does Vanguard have a quantum computing ETF?
No. Vanguard has no quantum computing ETF or mutual fund. Its closest fund is the Vanguard Information Technology ETF (VGT, 0.09%), which held IonQ, Rigetti, D-Wave and Quantum Computing Inc at a combined 0.19% on August 31, 2026. That is about $19 of quantum pure plays in every $10,000 invested.
Is there an ETF that invests in AI and quantum computing?
Yes. The Global X AI Semiconductor & Quantum ETF (CHPX, 0.50%) combines the two, although it is mostly a chip fund: Micron, TSMC and NVIDIA lead it and the quantum pure plays were 0.57% on September 29, 2026. QTUM also mixes them, because its index counts machine learning companies alongside quantum ones.
Is QTUM ETF a good investment?
That is a judgment we cannot make for you, but the facts are checkable. QTUM charges 0.40%, holds 86 stocks at close to equal weight and has $5.6 billion in assets. About 88% of it is companies such as Cloudflare, Palantir and AMD, so it behaves more like a broad technology fund than a bet on quantum hardware. If pure quantum exposure is the goal, that mix matters more than the fee.
What are the top 5 quantum computing companies?
By market value among US-listed companies whose main business is quantum computing, the five largest at the September 29, 2026 close were IonQ (about $17.5 billion), Quantinuum ($12.8 billion), D-Wave ($6.1 billion), Rigetti ($5.3 billion) and Infleqtion ($3.1 billion). IBM, Alphabet and Microsoft run large quantum programs too, but quantum is a small part of each.
Is it cheaper to build your own quantum computing basket than to buy an ETF?
Above a certain balance, yes. Fidelity Basket Portfolios charges a flat $4.99 a month, $59.88 a year, with no expense ratio. That beats a 0.77% fund above about $7,800, a 0.50% fund above about $12,000, a 0.45% fund above about $13,300, a 0.40% fund above about $15,000 and a 0.35% fund above about $17,100. Below those balances the ETF costs less.
Can I backtest a quantum computing ETF against my own basket?
Yes. In Indexes you build your basket, then build a second index that holds only QTUM or WQTM, and compare both against the S&P 500 or the Nasdaq-100 over the same dates. Keep in mind that several pure plays only listed between 2021 and 2026, so a basket that includes them can be tested only as far back as its youngest stock.
Sources
Expense ratios, assets and holdings from each issuer, read September 30, 2026: defianceetfs.com fund pages and full holdings files (QTUM, QTUP, QPUX, IONX), corgifunds.com (CQTM), globalxetfs.com fund page and holdings file (CHPX), amplifyetfs.com fund page and launch holdings flyer (XQBT). WisdomTree's live page could not be read, so WQTM figures are from the issuer page as captured on August 27 and 28 and from its Form N-PORT for June 30. Index and strategy rules from each fund's summary prospectus (Form 497K) on sec.gov. Pure play shares are our own sums of the published weights for IonQ, Quantinuum, D-Wave, Rigetti, Infleqtion, IQM, Quantum Computing Inc, Xanadu, Pasqal, Horizon Quantum, SEALSQ, BTQ, Arqit and Quantum eMotion. VGT weights from Vanguard's holdings as of August 31. Market values are approximate, from the September 29 close. Fidelity Basket Portfolios pricing from fidelity.com. Expense ratios and holdings change, so confirm them on the fund page before you buy. Indexes is not affiliated with any fund issuer or broker named here. We make index construction and backtesting software: we do not manage money, place trades or give investment advice, and backtested results are hypothetical.
Build the quantum index that holds what you meant to buy
Choose the names and the weights, backtest the basket against the S&P 500 and the funds, and track it every day. Then buy it wherever you invest.
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