SEOUL, Oct 23 (Reuters) - Hana Financial Group (086790.KS: Quote, Profile, Research), South Korea's No.4 banking group, on Friday reported that it swung to a quarterly profit, led by a strong pickup in net interest margins and as the stronger won helped reduce provisioning costs.

Hana, in which Singapore's Temasek Holdings [TEM.UL] and Goldman Sachs (GS.N: Quote, Profile, Research) own a combined 18 percent stake, earned 240.0 billion won ($202 million) in the quarter ended September, broadly in line with a forecast for 202.7 billion won from Thomson Reuters I/B/E/S.

That compared with its first ever net loss of 73.3 billion won a year earlier when bad loans from corporate failures eclipsed its operating profit, and against a 196.6 billion won profit in the second quarter.

Hana was able to write back part of the provisioning costs it had set aside to cover its exposure to currency option contract with display parts maker Taesan LCD (036210.KQ: Quote, Profile, Research) in the previous quarters, helped by the won's gain in the quarter. (Reporting by Kim Yeon-hee; Editing by Chris Lewis)