(CNN) -- For the third time in a year, Japan's government has intervened in the yen, its unit of currency, according to Japan's finance minister.

"While Japan is dealing with the reconstruction of the tsunami zone, if the surging of the yen continues, it could negatively affect Japan's economy and financial stability," Finance Minister Yoshihiko Noda told reporters. "Therefore, Japan has intervened in the currency market. We will continue to watch the movement of the currency market closely."

Minutes after the announcement, the Nikkei stock index shot up 100 points and the yen weakened against the dollar.

The Bank of Japan responded to the move in a press release, saying that it "strongly expects that the action taken by the Ministry of Finance in the foreign exchange market will contribute to stable price formation in the market."

Japan's economy, still struggling after the March 11 earthquake, tsunami and nuclear crisis, has been hit hard by the falling U.S. dollar. Uncertainty by global markets over the U.S. debt deal caused the dollar to plummet versus the Japanese yen, a currency seen as a safe haven by investors.

Japanese automakers and electronics companies have seen the currency shift eat into their corporate profits as the dollar has sunk. Japan's exporters operate on the global market with the U.S. dollar, but then repatriate the funds to Japan in yen. JP Morgan Japan estimates corporate profits have fallen approximately 5% in the last six weeks as the U.S. dollar has plummeted.

Perhaps the hardest-hit company is the world's largest automaker, Toyota. The car maker estimates it loses approximately $385 million for every 1 yen movement up versus the dollar. By that estimate, in July, Toyota lost more than a billion dollars based on the currency shift alone.

Toyota Motor Corporation this week, in announcing their first-quarter earnings for the 2012 fiscal year, called the exchange rate too much to bear. Senior managing officer Takahiko Ijichi said, "I understand that it's our fate to adapt to ever-changing exchanging rates. But this situation, where the yen has passed 80 yen and is now at 76 yen, for us exporters, it's extremely tough."

CNN's Kyung Lah contributed to this report.