China's yuan on Friday took its biggest tumble in the spot market since the reform of the exchange rate system in 2005. The Yuan fell by as much as 0.9 percent, or 500 basis points, almost the daily limit of 1 percent, to 6.1808 per U.S. dollar in Shanghai, but the decline narrowed in the afternoon before ending at 6.1450 per dollar. The People's Bank of China set the central parity rate of the yuan at 6.1214 per U.S dollar on Friday, 10 basis points stronger than that of 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 1 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.