The yuan climbed to a 19-year high on speculation China will step up efforts to arrest a seven-quarter slowdown in the world's second-largest economy.

The currency had its biggest gain in six months after the People's Bank of China strengthened its reference rate today by the most since Aug. 22. The central bank injected a record amount of funds into the financial system this week to address a cash squeeze ahead of a weeklong holiday that starts Oct. 1. The Shanghai Composite Index jumped 4.1 percent in the past two days, buoyed by a report suggesting policy makers plan to unveil measures to support Chinese stocks.

"Funds are flowing back into the market as people bet China will soon act more aggressively to revive growth," said Kenix Lai, a Hong Kong-based foreign-exchange analyst at Bank of East Asia Ltd. "There's always expectations that the government will announce important polices before or at the end of a long holiday. The stock market is also rallying on stimulus bets."