Fan Bao, CEO of China Renaissance Group, an investment bank led by one of the country’s most famed rainmakers, holds a news conference on its IPO in Hong Kong on Sept. 13, 2018.BOBBY YIP/Reuters The disappearance of a star Chinese dealmaker has left his bank struggling to reassure clients and staff, people with knowledge of the matter said on Monday, and has heightened concerns about “key man risk” for investors. Shares of China Renaissance Holdings fell by as much as 5 per cent on Monday, following a record low in the previous session after the investment bank said it could...