Tiny Japan Stock Soars—Then Buyout Announced

The stock of Apple supplier Minebea Mitsumi Inc. soared after its proposed acquisition of a Japanese lock maker, in a deal clouded by controversy over aggressive trading ahead of the buyout.

Tokyo-based Minebea climbed as much as 13 percent after unveiling its deal to acquire U-Shin Ltd., which provides electronic keys and steering locks to automakers. U-Shin shares climbed the most in five years on Wednesday -- just before Minebea announced its acquisition.