SEOUL (Reuters) - South Korea's foreign exchange authorities sold a net $5.80 billion for market intervention in the second quarter, central bank data showed on Monday.

It was the second straight quarter that the authorities sold dollars, after selling $1.82 billion a quarter earlier and the biggest quarterly selling since the second quarter of 2023 to curb losses in the local currency.

The Korean won ended the quarter down 2.1% against the dollar, after at one point touching its weakest level since November 2022, while the dollar index, a measure of the greenback's value against six major currencies, rose 1.3%.

(Reporting by Jihoon Lee)