Internet finance may be a new development in China but its impact is now everywhere.

Peking University has developed an index which measures the growth and structure of internet finance across China. It says the industry grew almost fourfold in the year to December 2015 and, on one measure, the market was then valued at $US1.8 trillion).

According to McKinsey, the internet economy is estimated to account for 7 per cent of GDP in China, compared with 4 to 5 per cent in the United States, Germany or Japan.

The most widely used internet finance service is third-party payments, a market dominated by two players, AliPay and WeChatPay, which at the end of 2015 had more than 270 million and 200 million active users respectively.