It has been a wild ride for investors in Alibaba Group Holding.

After the largest-ever initial public offering of stock, a year ago this week, shares of the Chinese Internet giant surged 75% in their first two months—only to begin a long spiral downward. They fell all the way to the initial price of $68 and then some, recently trading at about $64. The descent probably isn’t over. Alibaba’s shares could fall much further as China’s economy struggles, competition in e-commerce increases, and the company’s culture and governance...