Shares of Nidec Corp plunged as much as 22.44% Thursday, after the company announced a probe into allegations of improper accounting in its group.
This marks the largest one-day drop in the Japanese electronics components manufacturer's shares.
The Kyoto-based company is one of the world's largest manufacturers of mini or brushless motors used in devices like hard drives and larger motors found in electric vehicles, appliances, and factory robots.
Nidec shares have declined 10.61% since the start of the year. By comparison, the 225-stock Nikkei 225 index has risen 5.12% in the same period.
Nidec on Wednesday announced the creation of an independent third-party committee, after an internal investigation of its Chinese subsidiary, Nidec Techno Motor, revealed evidence suggesting the malpractice could be linked to its management.
"The investigations found multiple documents suggesting that, in addition to Techno, the Company and its group companies could have engaged in improper accounting with the involvement or knowledge of its or their management," Nidec said in a regulatory filing.
Nidec's latest announcement comes after it delayed the submission of its financial report in June over "potentially erroneous declarations" of country of origin reports for the manufacture of certain motors, which may have resulted in unpaid import tariffs.
Nidec also has operations in several countries, including India, China, France, Germany and the United States.
It recently deepened its presence in China with the opening of the Nidec Qingdao Industrial Park in Shandong, where its motor and electronic operations now operate under one facility.