China's central bank guided the yuan lower on Thursday at the fastest pace since its shock devaluation in August, prompting a shuttering of mainland stocks and roiling markets elsewhere.
The People's Bank of China (PBOC) set the yuan reference rate at 6.5646 against the dollar, down 0.51 percent from Wednesday's fix, and the lowest mid-point since 2011. That represents the largest daily change in the fix since August 13, according to Reuters data. The yuan had finished at 6.5554 on Wednesday.
China's central bank lets the yuan spot rate rise or fall a maximum of 2 percent against the dollar, relative to the official fixing rate.
The currency moves have revived a litany of concerns in financial markets, from the health of the Chinese economy that is growing at its slowest pace since the financial crisis to the impact of a weaker yuan on capital outflows, which have accelerated in recent months.
The more stocks fall on cues from a lower yuan, the more investors may be encouraged to yank funds out of China and park them overseas, in turn exerting further pressure on the yuan.
"The PBOC said the fix will be based on the previous day's close and a softer fix is therefore not inconsistent with market forces," said Vishnu Varathan, head of economics and markets strategy at Mizuho Bank's Singapore office.
"There is a sense in the market that the offshore market is getting carried away though and the PBOC would want to rein in excessively aggressive one-way bets," he said.