The report defines those owning from $100,000 to $2 million in assets as the moderately wealthy and states that this population group is experiencing the fastest growth in wealth.
Chinese "new wealth builders" will make up to $53 trillion by 2020, compared to the $27 trillion in total assets earned by their US counterparts.
In 2014, the United States topped the list of the world's moderately wealthy with its citizens in that segment holding a total of $23 trillion in financial assets, the report said.
The top-five rapidly growing countries in terms of assets are India, Indonesia, the Philippines, Thailand and Vietnam, the study said.
According to estimates by Forbes magazine, the sole remaining indicator where China lags behind the United States is in sheer number of rich people, including billionaires.