Shein Global Holdings Ltd. has lost about $5 billion in market value since its initial public offering as it finished one of the worst opening weeks after a major Hong Kong listing, underscoring investor concerns over the fast-fashion retailer’s growth outlook. Even after a 3.2% surge Monday, their first gain since the IPO, the shares closed 19% down from the HK$48.56 offering price. That’s the second-worst performance in the first five sessions among companies that raised at least $1 billion in...