Shares in China CSSC Holdings Ltd and China Shipbuilding Industry Co Ltd (CSIC) reached their 10-percent trading limit on Thursday after their parent firms announced that CSSC chairman Hu Wenming will now head CSIC among other management changes. "The top management reshuffle at CSSC and CSIC has sparked market speculation that the two shipbuilders may merge," the companies said in near-identical statements issued late on Thursday to the Shanghai stock exchange. "With respect to these merger rumors, the company and its parent have yet to receive any merger-related information from authorities." Trading in the shares of both firms was comparatively subdued on Friday, with CSSC down 0.56 percent and CSIC 0.48 percent higher at 0358 GMT.