The sudden slide of the Chinese currency over the past week has raised concern that the yuan is nearing levels that could trigger an unwinding of billions of dollars in highly leveraged bets on its appreciation.

Small and medium-size businesses and wealthy clients of private banks have been among the biggest buyers of financial products that profit from appreciation in the yuan, analysts say. They bought products that magnified profits from gains in the currency but that could lead to big losses if the yuan falls.

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