The U.S.-listed shares of Vipshop Holdings Ltd. /zigman2/quotes/205727205/composite VIPS -0.30% sank 5.7% in morning trading Thursday, and have now tumbled TK% amid a four-day losing streak, after disclosing that a large shareholder, JD.com Inc. /zigman2/quotes/205122565/composite JD -0.82% , sold off a chunk of its holdings in the past week. JD.com's stock fell 2.0% in morning trading. In an amended 13D filing Thursday morning, the China-based online apparel and accessories seller said fellow China-based ecommerce company JD.com owned 5.64 million Vipshop shares, or 4.3% of the shares outstanding. Just six days earlier, an amended 13D filing showed that JD.com owned 7.10 million shares, or 5.4% of the shares outstanding. In mid-April, another amended 13D filing showed JD.com owned 8.59 million Vipshop shares, or 6.3% of the shares outstanding. Vipshop's stock has rallied 14.0% year to date and JD.com shares have declined 9.3%, while the iShares China Large-Cap ETF /zigman2/quotes/208670743/composite FXI +0.13% has lost 8.7% and the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.74% has dropped 21.0%.