The completion of the deal, initially aimed for by end-March, had been delayed due to a prolonged review by Chinese antitrust authorities. China approved the deal last month.

The Bain consortium last year won a long and highly contentious battle for Toshiba Memory, the world's No. 2 producer of NAND chips. Toshiba put the business up for sale after billions of dollars in cost overruns at its Westinghouse nuclear unit had plunged it into crisis.

The consortium includes South Korean chipmaker SK Hynix, Apple Inc, Dell Technologies, Seagate Technology and Kingston Technology.

Under the deal with Bain, Toshiba repurchased 40 percent of the unit, it said in a statement.

(Reporting by Makiko Yamazaki; Editing by Sunil Nair)