China's central bank pumped 120 billion yuan ($17 billion) into the financial system on September 20.
The People's Bank of China (PBOC) injected 40 billion yuan ($5.6 billion) into the market through seven-day reverse repos at an interest rate of 2.55 percent, and conducted 80 billion yuan ($11.3 billion) of 14-day reverse repos at an interest rate of 2.7 percent.
With no reverse repos maturing, this led to a net injection of 120 billion yuan ($17 billion) on September 20.
The moves aimed to maintain stable liquidity near the end of the third quarter, the PBOC statement said.
A reverse repo is a process in which the central bank purchases securities from commercial banks through bidding, with an agreement to sell them back in the future.
China will keep its prudent monetary policy "neither too tight nor too loose" while maintaining market liquidity at a reasonably ample level in 2019.