BEIJING, Dec. 15 (Xinhua) -- The Chinese currency Renminbi, or the yuan, weakened 25 basis points to 6.3421 against the U.S. dollar on Thursday, according to the China Foreign Exchange Trading System.

In China's foreign exchange spot market, the yuan is allowed to rise or fall by 0.5 percent from the central parity rate each trading day.

The central parity rate of the yuan against the U.S. dollar is based on a weighted average of prices before the opening of the market each business day.