SanDisk (NASDAQ: SNDK) stock’s remarkable 5,302% rally since it got spun off from Western Digital (NASDAQ: WDC) in 2025 came at the cost of SNDK flashing a strong sell signal after becoming one of the most overbought equities in history. Specifically, by the time the markets closed on Friday, June 12, the memory firm saw its relative strength index (RSI) cross above 99 on a scale that tops at 100. SanDisk stock price and RSI chart. Source: Barch…