Why Did QuantumScape Stock Drop Almost 30% in the First Half of 2026?

QuantumScape’s stock fell 27.4% in the first half of 2026, raising questions for investors despite continued progress toward solid-state EV batteries. The company, which has been working to commercialize its separator technology, saw milestones last year that improved confidence, including expanded development and a licensing deal with Volkswagen Group’s battery unit PowerCo, plus partnerships with Corning and Murata for ceramic separators. QuantumScape also integrated its separator process into initial battery cell production and highlighted a real-world demonstration using a Ducati motorcycle. In 2026, it added an agreement with Honda’s R&D arm to enhance its battery platform. The article notes the broader market may extend beyond vehicles to applications like in-rack energy storage for AI-focused facilities. Still, competition and commercialization timelines remain key risks as the market cap is $4.3 billion.