At an official Chinese New Year's party earlier this year, a former bond trader named Zhu Changhong was hailed for the smart choices he made investing the world's largest stash of cash: China's $3.5 trillion in foreign reserves.

Tweaking the lyrics of a famous revolutionary song that extolled Mao Zedong, Zhu's colleagues jocularly lauded him: "The east is red, the sun rises. From China arises Zhu Changhong…he is SAFE's saviour," people with knowledge of the event say. SAFE is China's State Administration of Foreign Exchange, the division of the central bank that manages China's currency reserves and is one of the most powerful investors in the world.