Grouping of large Japanese financial and industrial corporations through historical associations and cross-shareholdings. In a keiretsu each firm maintains its operational independence while retaining very close commercial relationships with other firms in the group. Horizontal keiretsus (such as Mitubishi Corp. and Sumitomo Corp.) involve firms in different industries whereas vertical keiretsus (such as Toyota Corp. and Sony Corp.) involve firms upstream and downstream of a manufacturing process. Keiretsu is Japanese for a headless combine and used to be written as zaibatsu.
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