My wallet thanks you. From the NYT. TOKYO — As global investors flee the dollar and euro for refuge in stronger currencies, those havens have started to send out a message: enough. Demand for currencies like the Japanese yen and Swiss franc, seen as relatively safe assets to hold in turbulent times, have surged in recent weeks, driving up their value as investors have dumped dollars and euros as a result of debt worries in the United States and Europe. Declaring the yen’s rise to be a threat to the economy, Japan’s Ministry of Finance moved on Thursday to reverse the trend, a day after the typically sedentary Swiss bank unexpectedly cut interest rates in an effort to weaken the franc. A strong currency might sound like a validation of investor confidence in the performance of an economy. But for trade-dependent Japan and Switzerland, a sudden jump in the value of their currencies can wreak havoc by making their exports uncompetitive. By intervening, though, Japan and Switzerland risk criticism that they are inciting what some market players call “currency wars,” where countries compete to devalue their currencies. Both countries also devalued their currencies last year. South Korea and Brazil intervened in foreign exchange markets earlier this year. And China has long purchased dollar- and yen-denominated assets in an effort to keep its renminbi weak enough to sustain its export economy. “In a dream world where the Ministry of Finance and Bank of Japan could dictate exchange rates, they certainly won’t mind to see the yen weaken to 85-90 yen against the dollar,” Takuji Okubo, chief economist in Tokyo for Société Générale, wrote in a note to clients. “However, with all the developed economies in the world suffering, trying to grow through a weaker currency is likely to encounter resistance.” But Japan right now sees itself having little choice. “The recent rise in the yen in currency markets has been one-sided and unbalanced,” Finance Minister Yoshiko Noda said on Thursday as he announced the start of the intervention. “If this trend were to continue, it would harm the Japanese economy, even as we do all we can to recover from our natural disasters.” On Thursday, Japanese authorities delivered a one-two punch. First, the Finance Ministry said it had begun selling yen and buying dollars. Then the Bank of Japan announced that it had further expanded its program to purchase government and corporate bonds, a form of monetary easing aimed at increasing liquidity and helping to dilute the value of the yen. The yen weakened steadily throughout the day, from 77.15 yen to the dollar to about 80 yen on Thursday evening in Tokyo. Earlier this week, the yen came close to a record high of near 76.25 yen to the dollar. At midday Thursday in New York, the yen was trading at 78.96 to the dollar. “We judged that rises in the yen have economic costs, including the risk of damaging corporate sentiment and encouraging companies to shift production overseas,” the governor of the Bank of Japan, Masaaki Shirakawa, said at a news conference. Japan, which had taken a laissez-faire approach to currency policy from about the middle of the last decade, has over the last year become more willing to intervene. Last Sept. 15, with concerns over the American economy mounting, it spent 2.1 trillion yen in its biggest one-day intervention ever. On March 18, a week after an earthquake, tsunami and subsequent nuclear crisis, the Group of 7 industrialized economies came to Japan’s aid by staging a joint intervention, coordinating efforts to sell the Japanese yen on global currency markets. Traders had attributed the yen’s surge to Japanese companies repatriating funds to finance recovery back home. But since then, the dollar has again slumped against the yen, falling 5 percent in the last month as investors wary of the debt impasse in the United States fled to other currencies. Even after lawmakers in Washington struck a deal on Tuesday to avert a default or downgrade of United States debt, fresh concerns over the economy again weighed on the dollar.