Quantum Stocks Looked Like Nvidia in 2019. Then They Belly-Flopped 50%.

Back in June, I made a big call: quantum computing looked a lot like Nvidia (NVDA) in 2019, and the sector could be sitting at the beginning of a generational investment cycle. My favorite speculative pure-play was IonQ (IONQ), while IBM (IBM) and Alphabet (GOOGL) were my safer megacap choices, and Defiance Quantum ETF (QTUM) was my diversified option. 

Then, many of the very same quantum stocks I wrote about took a dive this summer, and it wasn’t the graceful kind. More like a belly flop off the high board.

Why Did Quantum Stocks Plunge Around 50% This Summer?

IonQ hit $73.65 on June 3 before crashing to $31.81 on July 29, 2026, or about a 57% decline from peak to trough. 

Of course, it wasn’t the only one. Rigetti Computing (RGTI) fell about 53% from $28.06 on June 3, 2026, to $13.13 on July 29, 2026.

D-Wave Quantum (QBTS) dropped around 49% from $31.55 on May 22, 2026, to $16.02 on July 17, 2026.

Quantinuum (QNT) went through a similar move after its IPO. It fell from $86.79 on July 6 to $47.06 on July 29, 2026, before rebounding.

Then August arrived, and the same stocks snapped right back up. IonQ rebounded about 51% from its July low to its next August high; Rigetti gained 48%; D-Wave recovered 37%; and Quantinuum climbed around 54% from its July low.

But this rally did very little to erase the damage. IonQ, for example, remained well below its…