SanDisk shares fell sharply Monday following an announcement from former parent company Western Digital. Western Digital is developing post-quantum cryptography hard drives, raising investor concerns that the technology could reduce future demand for SanDisk’s core NAND memory products.
The sell-off also reflects broader profit-taking after a significant rally throughout 2026. SanDisk ended that year as a top performer in the S&P 500, leading some investors to exit positions amid concerns over the company’s high valuation.