Police in eastern China’s Zhejiang province have detained Yu Faxiang, the chairman of Hong Kong-listed Haichang Ocean Park Holdings, as authorities investigate alleged mismanagement following defaults on multibillion-yuan wealth products issued by a firm under his control. It is the latest crackdown on mainland China’s shadow banking system, continuing years of government efforts to clean up the sector. Police have imposed “criminal compulsory measures” against Yu and were conducting a probe...