Shares fell 14.2 percent to $92.40 at 3:36 p.m. in New York.
Third-quarter revenue is projected to be $1.68 billion to $1.73 billion, the Milipitas, California-based company said in a statement late yesterday. That was short of analysts' average estimate of $1.74 billion.
SanDisk also reported second-quarter profit and revenue that barely beat analysts' expectations.
Net income rose 4.6 percent to $273.9 million, or $1.14 per share. Excluding one-time items, SanDisk earned $1.41 per share.
Revenue rose 11 percent to $1.63 billion.
Analysts had expected a profit of $1.39 per share on revenue of $1.60 billion.
SanDisk's growing focus on high-end solid-state drives, or SSDs, helped offset volatile prices for memory chips, powering the company's stellar results and, since late March, its stock's rise to life-high levels.