The yen moved past 160 per US dollar to its weakest level in a month, extending a slide that has erased more than half of its intervention-fueled gains, according to Bloomberg. The Japanese currency fell as much as 0.5% to 160.20 versus the greenback on Friday after the dollar got a boost from Federal Reserve Chairman Kevin Warsh's vow to hit the central bank's inflation target, with traders now watching for signs of when authorities might move to protect the currency. Hedge funds added to short yen bets for a second straight week, according to Commodity Futures Trading Commission data for the period ending Aug. 25.