Prediction: If a September Sell-Off Hits Speculative AI Stocks, Quantum Computing Falls First

Historically, September has been on average the worst month of the year for stocks, with the S&P 500 (SNPINDEX: ^GSPC) declining by an average of 1.16% in September from 1926 through 2024. But historical trends do not mean that stocks will necessarily fall in September 2026.

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However, several events could make markets volatile, including the August jobs report coming out on Sept. 4 and the U.S. Federal Reserve's next meeting on Sept. 15 and 16. High inflation, massive and rising government debt, and elevated geopolitical tensions have also increased uncertainty in the stock market. If any of these factors help trigger another sell-off in speculative technology stocks, quantum computing stocks could be among the hardest hit.

When tech stocks sell off, quantum computing stocks sell off harder

A review of daily stock price data shows that through Aug. 28, there were 23 trading days in 2026 when the Invesco QQQ Trust (NASDAQ: QQQ) fell at least 1.5%. QQQ, an exchange-traded fund that tracks the Nasdaq-100, declined by an average of about 2% on those days.

However, the median return for IonQ (NYSE: IONQ), D-Wave Quantum (NASDAQ: QBTS), Rigetti Computing (NASDAQ: RGTI), and Quantum Computing Inc. (NASDAQ: QUBT) was worse than the QQQ on 17 of those 23 trading days -- about 74% of the time.

In short, quantum computing stocks have tended to decline more sharply than the tech sector during broader technology sell-offs in 2026.

Quantum computing investors are paying heavily for future growth

The biggest risk for quantum computing stocks is their high valuations, even compared to other types of risky technology stocks. Software companies such as C3.ai (NYSE: AI) and BigBear.ai (NYSE: BBAI) are also losing money and depend on future growth, but they trade at 6.9 times and 10.1 times forward sales, respectively.

IonQ has stronger commercial traction than most pure-play quantum computing companies. Its revenue jumped 287% year over year to $80.1 million in the second quarter. Its remaining performance obligations (RPO), a measure of contracted revenue that has not yet been recognized, rose 297% year over year to $485 million. Management now expects revenues for 2026 in the range of $280 million to $290 million, up from the previous guidance range of $260 million to $270 million.

Despite this solid performance, IonQ is trading at nearly 52 times forward sales. Hence, the stock is already pricing in significant anticipated future growth, leaving less of a cushion if it has execution problems, or if investors become more cautious about speculative technology stocks.

Rigetti Computing's valuation looks even more demanding. It trades at more than 223 times forward sales. Rigetti Computing generated only $5.1 million in revenue in the second quarter while posting a $28.1 million operating loss.

D-Wave Quantum trades at nearly 148.8 times forward sales. The company's second-quarter revenue was only $3.1 million. However, there are signs that demand is improving. The company's remaining performance obligations were up 668% year over year to $40.7 million, while bookings in the first half of 2026 rose 1,120% year over year to $35.5 million.

Hence, quantum computing technology need not fail for these stocks to fall. Although the companies may continue to make commercial progress, investors could simply become less willing to pay such high valuations for revenue that's expected much further in the future.

Why the recent sell-off does not remove the risk

Quantum computing stocks have already witnessed a sharp correction. IonQ is down almost 53.7% from its 52-week high, while D-Wave Quantum is down about 63.7%. Rigetti Computing and Quantum Computing Inc. have fallen even more, by roughly 73.2% and 68.5%, respectively, from their 52-week highs (as of Aug. 28).

Many of these companies have strong balance sheets. Rigetti Computing and D-Wave Quantum exited the second quarter with $541.3 million and $546.2 million in cash and marketable investments on their books, respectively. IonQ reported around $3 billion in cash, cash equivalents, and investments at the end of the second quarter, before adjusting for its SkyWater acquisition. These large cash balances reduce the companies' near-term financing risks.

However, that does not mean the stocks cannot fall further. Rigetti Computing can see its valuation compress from more than 200 times forward sales. Similarly, IonQ can continue reporting strong revenue growth while investors become less willing to pay around 52 times forward sales. The recent correction may have reduced their stock prices, but it has not removed their valuation risk. These companies are still heavily dependent on the premise that they will experience a great deal of future commercial growth to justify their current valuations.

The clearest sign that this prediction is not playing out would be if quantum stocks stop underperforming the Nasdaq-100 during broader technology sell-offs. Until then, their performance in 2026 suggests that they remain particularly vulnerable when investors move away from speculative technology stocks.

Manali Pradhan, CFA has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends IonQ. The Motley Fool recommends C3.ai. The Motley Fool has a disclosure policy.