Shein shares plunged on Tuesday after the fast-fashion retailer reported a 67% decline in quarterly profit in its first results sincelisting in Hong Kong, raising questions about whether the company’s rapid growth can continue without sacrificing margins. The stock fell as much as 14% before paring some of the decline, leaving Shein’s market value at about $17 billion by the midday break, down sharply from roughly $26 billion when the China-founded, Singapore-headquartered company began trading in Hong Kong on September 1. The sell-off reflects a problem that investors had been waiting to see in Shein’s post-IPO results: whether its growth model can withstand rising logistics costs, tougher regulation and weaker demand in some major markets. Adjusted net profit fell to $228 million in the second quarter ended June 30, while the profit margin narrowed dramatically to 2. Jefferies analysts estimated that quarterly earnings came in more than 10% below the lower end of the range implied by Shein’s prospectus.