What Now For Quantum Stocks?

Five years ago this month, a quantum company rang the opening bell on a US exchange for the first time. That company was Arqit, a British quantum encryption firm briefly valued at close to $3 billion, now valued considerably less. Seven pure-play quantum computing companies have followed it onto American markets since, and between them they have produced a five-year record that deserves closer inspection. I have assembled the complete daily closing record for every quantum listing, from each company’s first session through the end of August 2026, and built it into a Pure Play Quantum Index, equal-weighted and rebalanced monthly, with the methodology published alongside. The data settles several questions that coverage of this sector usually leaves to impression. All figures are closing prices, which sit slightly below the intraday extremes commonly quoted, and nothing in this piece is investment advice. IonQ listed first among the pure plays in October 2021 at a $9.20 first close and trades at $39.31 today. Rigetti and D-Wave followed in 2022 near ten dollars and are up 66 and 72 per cent, respectively. After a long gap, the class of 2026 arrived: Infleqtion in February,…