Shares of SanDisk Corp., which makes memory chips used in mobile devices, declined as much as 10 percent in extended trading Thursday after the company gave a second-quarter sales forecast that fell short of some analysts’ estimates.

The Milpitas, California-based company said revenue will decline to about $1 billion, plus or minus $50 million. Analysts on average had estimated sales of $1.28 billion, according to data compiled by Bloomberg.

SanDisk shares, which had fallen less than 1 percent to $40.47 at the close in New York, traded as low as $36.44 in late trading.