China's central bank on Friday set the mid-point of the yuan's exchange rate against the U.S. dollar at 6.7720, up 138 basis points from the previous session. This is the highest level since China revalued the yuan in a landmark move in 2005.

Since China pledged to make the yuan more flexible on June 19th, the currency has hit a series of peaks. But the central bank had also warned that the reform did not mean a one-way upward trend for the exchange rate.