Nidec Corp. shares slid after the company discovered more suspected cases of improper bookkeeping, heightening fears the world’s biggest maker of mini motors may come under regulatory scrutiny for a potential delisting. The latest revelations emerged from an external probe that began earlier this month when Nidec found evidence of systemic accounting problems. It has over 300 group companies, and it’s possible that more cases of improper accounting will emerge, given seemingly inadequate internal controls, she added. In the past, that label has been imposed on Toshiba Corp. and Olympus Corp., although both avoided getting tossed off bourses. Shares will likely remain sluggish until the third-party committee’s findings are made public, he said.