ARQQ vs QUBT vs IONQ vs RGTI

For growth investors, IonQ, Inc.

(IONQ) is the stronger pick with 201. 9% revenue growth year-over-year, versus -34. 3% for Rigetti Computing, Inc. (RGTI). Analysts rate Arqit Quantum Inc. (ARQQ) a "Buy" — based on 2 analyst ratings — the highest consensus in this comparison. The "better buy" depends entirely on your goals: growth investors should weight revenue trajectory, value investors should weight P/E and PEG, and income investors should weight dividend yield and streak.

Over the past 5 years, IonQ, Inc.

(IONQ) delivered a total return of +385. 6%, compared to -93. 9% for Arqit Quantum Inc. (ARQQ). Over 10 years, the gap is even starker: QUBT returned +9599% versus ARQQ's -93. 8%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.

By beta (market sensitivity over 5 years), IonQ, Inc.

(IONQ) is the lower-risk stock at 2. 90β versus Arqit Quantum Inc. 's 3. 70β — meaning ARQQ is approximately 28% more volatile than IONQ relative to the S&P 500. On balance sheet safety, Quantum Computing, Inc. (QUBT) carries a lower debt/equity ratio of 0% versus 3% for Arqit Quantum Inc. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), IonQ, Inc.

(IONQ) is pulling ahead at 201. 9% versus -34. 3% for Rigetti Computing, Inc. (RGTI). On earnings-per-share growth, the picture is similar: Quantum Computing, Inc. grew EPS 84. 9% year-over-year, compared to -16. 7% for IonQ, Inc.. Over a 3-year CAGR, IONQ leads at 126. 9% annualised revenue growth. Higher growth typically commands a higher valuation multiple — check whether the premium P/E or P/S is justified by the growth rate using the PEG ratio.

IonQ, Inc.

(IONQ) is the more profitable company, earning -392. 6% net margin versus -66. 7% for Arqit Quantum Inc. — meaning it keeps -392. 6% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: IONQ leads at -487. 4% versus -74. 9% for QUBT. At the gross margin level — before operating expenses — IONQ leads at 40. 4%, reflecting greater pricing power or product mix advantage. Stronger margins indicate durable pricing power, lower cost of revenue, or higher mix of software/services. They are one of the clearest signs of business quality.

None of the stocks in this comparison currently pay a material dividend.

All are effectively zero-yield and should be held for capital appreciation rather than income.

For long-horizon retirement investors, Quantum Computing, Inc.

(QUBT) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (+9599% 10Y return). Arqit Quantum Inc. (ARQQ) carries a higher beta of 3. 70 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (QUBT: +9599%, ARQQ: -93. 8%), confirming both are viable long-term holds — but the lower-volatility option typically results in less emotional selling during corrections. Retirement portfolios generally favour predictability over maximum returns. Consult a financial advisor before making allocation decisions.

Both stocks operate in the Technology sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

In terms of investment character: ARQQ is a small-cap high-growth stock; QUBT is a small-cap high-growth stock; IONQ is a mid-cap high-growth stock; RGTI is a small-cap quality compounder stock. These fundamental differences mean investors should not choose between them on a single metric — the "better stock" depends entirely on which of these characteristics aligns with your investment strategy.