An electronic board at a Hana Bank dealing room in Seoul shows the won trading at 1,529 per US dollar on Tuesday morning. (Newsis) The won-dollar exchange rate showed limited volatility in the first session of Seoul's 24-hour foreign exchange trading system, with the newly added early-morning hours passing without sharp moves.The rate traded around 1,531 won per dollar as the newly added 2 a.m. to 6 a.m. window began, eased to the 1,529 level after 4 a.m., and returned to 1,530 by the close, according to combined data from Seoul Money Brokerage Services and Korea Money Brokerage Corp.Moves were sharper during regular Seoul trading, though still contained. The rate opened at 1,527.60 won per dollar at 6 a.m. Monday, climbed to 1,537.50 shortly after the daytime market opened, then quickly retreated to 1,526.70 later in the morning. It closed the regular session at 1,530.30 at 3:30 p.m.Monday marked Seoul's first day of around-the-clock won-dollar trading, with transactions now running from 6 a.m. to 6 a.m. the following day, except on weekends and Jan. 1.The quiet debut may ease initial concerns that thinner overnight liquidity could amplify won swings when major global events hit outside Seoul trading hours. With no major overnight catalyst, volatility remained contained on the first day.Liquidity remained thin outside Seoul's daytime session, however, with trading still concentrated during regular hours and around the 3:30 p.m. close, while activity dropped sharply in the newly added early-morning window.Separate data from Korea Money Brokerage showed that total won-dollar trading reached $2.32 billion on Monday, more than double the $1.05 billion recorded on the previous trading day Friday and above the roughly $2 billion daily average logged in June.Meanwhile, the dollar index, which measures the greenback against six major peers, rose above 101 on Monday before giving back part of its gains and moving around the 100.8 level early Tuesday.The won opened Tuesday's session at 1,530 per dollar at 6 a.m., 0.3 won stronger than the previous daytime close, and was trading around 1,522 near noon.