A national flag of Japan flies near a container port on Jan 20, 2022, in Tokyo. (EUGENE HOSHIKO / AP)

TOKYO – Japan's current account suffered the biggest year-on-year decline in the first half of this fiscal year since the 2008 global financial crisis, as the trade balance fell into deficit due to a weakening yen and rising global commodity prices.

In the April-September period, the current account surplus more than halved from a year earlier, falling 58.6 percent to 4.8458 trillion yen ($33.36 billion), data from the Ministry of Finance showed on Wednesday.

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That was the biggest fall since the second half of fiscal 2008 and the second-largest since comparable data became available in 1985.

Japan posted a record primary income surplus of 18.2332 trillion yen in the first half of this fiscal year as rising global commodity prices boosted profits at trading companies and a 22 percent fall in the yen to the dollar helped inflate the value of gains from overseas investments

The current account surplus fell to a level last seen in 2014 when rising oil prices tipped Japan's trade balance into the red, the data showed.

Meanwhile, Japan posted a record primary income surplus of 18.2332 trillion yen in the first half of this fiscal year as rising global commodity prices boosted profits at trading companies and a 22 percent fall in the yen to the dollar helped inflate the value of gains from overseas investments.

The income gains more than offset a trade deficit of 9.2334 trillion yen.

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The data highlights an ongoing shift in Japan's main source of earnings, away from trade towards returns from overseas investments.

Japan's current account surplus has long been regarded as a sign of export might and a source of confidence in the safe-haven yen, but the account has occasionally fallen into deficit on a monthly basis in recent years.

For the month of September, Japan's current account surplus stood at 909.3 billion yen, above economists' median forecast for a surplus of 234.5 billion yen in a Reuters poll.

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While a weakening yen makes imports more expensive, it also makes exports cheaper for foreign buyers. But the boost to exports from a weaker yen will likely be more limited than expected as firms have shifted their production abroad over the past three decades.