Currency-market intervention is most effective when it’s a “surprise,” a senior Japanese Finance Ministry official said, sending a warning to traders that Japan is prepared to act again to stem the yen’s advance. “A surprise move would probably be effective to some extent,” Japanese Vice Finance Minister Fumihiko Igarashi said in an interview in Tokyo yesterday. “We can’t make an announcement in advance that we will act, but, on the other hand, we can’t say that we won’t act either.” Group of 20 finance authorities said last weekend that while countries should refrain from “competitive devaluations” of exchange ... (full story)