The cash-and-stock offer values SanDisk at $86.50 (roughly Rs. 5,630) per share, or a total equity value of about $19 billion, using a five-day volume weighted average price ending on Oct. 20 of $79.60 (roughly Rs. 5,185) per share of Western Digital stock.
SanDisk's shares rose 6.4 percent to $80 in pre-market trading. Western Digital's shares were down 1.1 percent at $74.
Demand for cheaper chips and new products to power Internet-connected gadgets, as well as a push from technology companies to consolidate suppliers, has led to record levels of dealmaking in the semiconductor sector this year.
The value of the SanDisk acquisition will depend on the closing and approval of an investment from a unit of China's state-backed Tsinghua Holdings Co Ltd, Unisplendour Corp Ltd in Western Digital, the companies said on Wednesday.
The deal is expected to close in the third calendar quarter of 2016.
© Thomson Reuters 2015