Quantum computing stocks like IonQ, Rigetti, and D-Wave have seen massive gains since October 2024, with some up over 3,000%. Despite the momentum, a new analysis points out five reasons the sector could face a downturn by 2026. The main risks mentioned are typical early-stage bubble cycles and the likelihood of share dilution as these companies burn cash to grow. Valuations are also looking stretched with price-to-sales ratios pushing past historical limits. On top of that, big tech giants like Alphabet and Microsoft are building their own quantum tech, which puts pressure on the pure-play companies that have less capital.