Shares of memory chip maker SanDisk plummeted nearly 31 percent to $9.91 per share after the bell on the news that Samsung has dropped its offer to acquire the troubled semiconductor company. Samsung first made its $26 per share offer six months ago in a letter to SanDisk’s board of directors, which rejected it as too low. Samsung’s decision to rescind its offer follows SanDisk’s financial results announcement on Monday. SanDisk reported a third-quarter loss of $155 million, which was well below Wall Street expectations.