IonQ Tumbles 3.10% with $2.16B Volume Ranking 35th as Quantum Sector Wavers

On September 26, 2025, IonQ (IONQ) closed with a 3.10% decline, marking its worst one-day performance in recent weeks. The stock’s trading volume of $2.16 billion ranked it 35th among all listed equities, though this figure represented a 30.55% drop compared to the previous day’s activity. Market observers noted the move reflected broader sector-wide caution amid mixed signals from quantum computing investors.

The downward pressure on IONQ came as industry participants awaited clarity on regulatory frameworks for quantum computing applications. Analysts highlighted that recent technical developments in error-correction algorithms had yet to translate into tangible commercial progress, leaving investors skeptical about near-term profitability. Additionally, macroeconomic concerns, including rising interest rates, weighed on growth stocks disproportionately, with IONQ’s high valuation multiples amplifying its sensitivity to shifting market sentiment.

Regarding the back-test request: The analysis requires specifying a stock universe (e.g., NYSE/Nasdaq top 500 by volume) and confirming whether a composite-index approach is acceptable. Precise execution of a 500-stock portfolio would necessitate external index construction, while an approximate method could involve a volume-weighted index. Further details are needed to proceed with the calculation framework.