Shares of Western Digital Corp. [S: WDC] were surging 10% in premarket trading Tuesday after Elliott Investment Management called for the company to split its business in two and offered at least $1 billion in capital to help with a separation. Elliott issued a letter to Western Digital's board of directors saying that while the company has "great potential" in both its hard-disk drive and flash businesses, it has "underperformed-operationally, financially and strategically.