By Stephen Aldred and Matthew Miller HONG KONG/BEIJING (Reuters) – When a fast-growing private equity firm co-founded by Jack Ma sought funding from institutional investors for the first time in early 2013, almost all had one major concern, its chairman said: was the firm independent from Ma, the influential executive chairman of Alibaba Group Holding, Chinas e-commerce giant. The investors were worried that Yunfeng Capital might not put their interests first, said David Yu, a long-time friend and business associate of Ma, speaking to Reuters in a rare interview at his Hong Kong office on July 3. Yu said the independence of Yunfeng from Ma was the number one concern institutional investors had.