Quantum computing stocks are back on the rise. Here’s why IONQ, QBTS, RGTI, and QUBT are up

World Quantum Day coincided with a significant surge in stock prices for the four major American quantum computing companies: D-Wave, IonQ, Rigetti, and Quantum Computing Inc. These companies, collectively known as the "Quantum Four," experienced double-digit gains, with D-Wave up 15.8% and IonQ up 20.1%. This upward trend continued into premarket trading, indicating sustained investor interest. The primary drivers behind this stock market rally were strategic announcements from IonQ and D-Wave. IonQ revealed a groundbreaking technical milestone: the successful photonic interconnection of two independent trapped-ion quantum systems. This advancement, crucial for future quantum networking and data sharing, also led to a significant contract with DARPA, exciting investors. Meanwhile, D-Wave's CEO, Alan Baratz, highlighted quantum computing's potential to revolutionize the tech industry, directly challenging Nvidia's dominant position in AI. Baratz emphasized quantum computers' superior energy efficiency and processing speed compared to classical GPUs. He noted that a quantum computer uses significantly less power to perform tasks that would take classical computers millions of years. These announcements from IonQ and D-Wave created a ripple effect, boosting the entire Quantum Four, as investors perceived the news as a positive signal for the broader quantum technology sector. Despite these recent gains, the Quantum Four have had a challenging year, with all four companies still down year-to-date. Investor sentiment in 2026 had been dampened by concerns about the long timeline for widespread quantum computing adoption and broader macroeconomic and geopolitical uncertainties.