Japan spent a record 7.98 trillion yen, about $50.4 billion, in a single day in July to support the yen, according to finance ministry data released on Monday, in the largest one-day currency intervention on record.

The quarterly figures for July to September show Japanese authorities stepped into the foreign exchange market on three days, 30 July, 31 July and 3 August, buying a total of 15.4 trillion yen, about $97.2 billion, to shore up the currency against the US dollar. It was the largest monthly yen-buying operation on record.

The previous single-day record was 6.28 trillion yen, set on 30 April, according to ministry data dating back to 1991. Japan acted alone on 30 July, the day before the Bank of Japan's monetary policy decision, when the yen had fallen to its weakest levels in 40 years, near 164 per dollar.

On 31 July, Japan spent a further 5.55 trillion yen, in what was the first coordinated US-Japan action to support the yen in almost three decades, with the United States selling euros for yen. A further 1.87 trillion yen was spent on 3 August.

The daily breakdown confirms details of the record monthly intervention previously disclosed by the ministry, which covered the period from 30 July to 26 August. The operation drove the dollar down from nearly 164 yen to about 155.20 within hours, although the yen later drifted back towards 159.

US Treasury Secretary Scott Bessent and Japanese Finance Minister Satsuki Katayama said at the time that the intervention was aimed at curbing disorderly currency moves and that they stood ready to act again if necessary. The ministry has confirmed no intervention took place between 29 September and 28 October, extending the pause that followed the summer operation.