Chinese businesses are hoarding dollars because they expect their own currency to weaken, and that in turn is exacerbating a slide in the yuan that has been driven by wobbly stock markets and feeble growth in the world's second largest economy.

This feedback loop has been playing out for months in mainland currency markets, spurred on by the dollar's rising yield. Foreign exchange deposits have climbed $53.7 billion since September to $832.6 billion, People's Bank of China (PBOC) data shows.

Analysts say one of two things needs to happen to end the downward spiral: the Federal Reserve needs to make deep rate cuts or the yuan needs to hit some form of a trough. Both seem distant.