Alibaba Group Holding Ltd. is calling off an initial public offering for its Cainiao logistics arm in Hong Kong, shelving a much-anticipated debut that could have raised more than $1 billion.China’s e-commerce pioneer, which owns 64% of Cainiao, said in a Tuesday filing it now plans to buy out all remaining stock held by investors and employees for $3.75 billion. The company decided to postpone the transaction because of poor market conditions, people familiar with the matter said. It lost its t...