The US Treasury informed a number of banks that it may intervene in the Japanese yen market on Friday and that they should "stand ready for future action."

July 30 : The dollar sank against the Japanese yen on Thursday with traders alert to the possibility of intervention from Japan to prop up its stubbornly weak currency. The dollar…

Having collapsed to its weakest relative to the dollar in 40 years...

Coordinated actions seen as joint effort to curb yen weakness