Five Chinese firms are being investigated for not issuing their annual reports on time.
The China Securities Regulatory Commission (CSRC) said the companies could be guilty of information disclosure violations.
Trade in their shares has been suspended while the investigations are ongoing.
The five firms are as follows: ShangHai ZhongYiDa Co Ltd, Xinjiang Yilu Wanyuan Industrial Investment Holding Co., Ltd, Zhejiang Great Southeast Co Ltd, Changsheng Bio-technology Co Ltd and Chengdu Huaze Cobalt & Nickel Material Co Ltd.

Abu Dhabi aims for 80% local materials in housing projects
UAE Central Bank support package reaches AED 6.2 billion
Dubai Holding picks 15 scale-ups from 1,400+ applicants for sustainability challenge
ADNOC backs UAE's AED1 billion National Industrial Resilience Fund
Trump sets deadline for EU to comply with trade deal or face 'much higher' tariffs
