Alibaba Group Holding Ltd's financial affiliate has received an investment from the National Social Security Fund, part of a private placement that values the unit at more than $40 billion.

Wang Zhongmin, vice-chairman of the National Council for the Social Security Fund, said on Thursday that the organization had taken a 5 percent stake in Zhejiang Ant Small and Micro Financial Services Group Co Ltd, owner of mobile payment platform Alipay.

Referring to the deal as a case of "an elephant falling in love with an ant", Wang said: "Seeing how online finance has boomed, we believe the market value of Internet financial institutions will more than double." He made the comment during an investment forum.