Shanghai police has detained Wang Zhenhua the billionaire founder and controlling stakeholder Future Land Development Holdings Ltd. The news sparked a record tumble in the stock and fueled speculation it may have to sell assets to rivals. All these are also highlighting a broader issue when it comes to China: key man risk. About 13% of listed Chinese businesses have a shareholder who owns a stake of 50% or more according Bloomberg data. Jeanny Yu reports on Bloomberg Markets: Asia. Bloomberg Opinion columnist Shuli Ren also speaks.