Western Digital Corporation said on Wednesday that it had agreed to acquire the memory chip maker SanDisk Corporation in a cash-and-stock deal worth about $19 billion.

Under the terms of the deal, SanDisk investors would receive $86.50 a share in cash and stock for each share they hold, representing a 15 percent premium to SanDisk’s closing price on Tuesday.

“This transformational acquisition aligns with our long-term strategy to be an innovative leader in the storage industry by providing compelling, high-quality products with leading technology,” Stephen D. Milligan, the Western Digital chief executive, said in a news release.

“The combined company will be ideally positioned to capture the growth opportunities created by the rapidly evolving storage industry,” he added.