SHANGHAI, July 21 (Reuters) - Ant Group"s money market fund Yu"e Bao shrank nearly 20% in size in the second quarter, according to Tianhong Asset Management Co Ltd, which manages the fund. The net asset value of Yu"e Bao stood at 780.8 billion yuan ($120.59 billion) at the end of June, according to the fund"s second-quarter report published on Thursday, down 19.7% from 972.4 billion yuan at the end of March. China has put Jack Ma"s Ant Group under tough regulatory oversight and capital requirements, and required it to cut links between its hugely popular payments app Alipay and its other businesses. ($1 = 6.4751 Chinese yuan renminbi)