China's central bank on Monday allowed 180 billion yuan (around 27 billion U.S. dollars) to drain from the market. 
The People's Bank of China (PBOC) put 90 billion yuan into seven-day reverse repos, a process by which central banks purchase securities from banks with an agreement to sell them back in the future, according to China's (Xinhua) News Agency. 
The reverse repos were priced to yield 2.25%, according to a PBOC statement. 
Reverse repos worth 270 billion yuan matured on Monday, so the central bank has effectively drained 180 billion yuan from the market. 
On Monday's interbank market, the benchmark overnight Shanghai Interbank Offered Rate (Shibor) was 2.01%, down 1.3 basis points from the previous trading day.