China’s yuan held steady against the dollar on Friday, but posted its biggest weekly loss on record due to the central bank’s surprise move to devalue its currency. The People’s Bank of China (PBOC) set the midpoint rate (CNY=SAEC) at 6.3975 per dollar prior to market open, firmer than the previous day’s closing quote 6.399. The yuan fell by 2.9 percent for the week.