A fall in loan-loss reserves.
This boosted Woori Finance's third-quarter earnings by 3.8 percent.
Net profit amounted to 503.9 billion won or US$461.6 million in the July-September period, from 485.5 billion won the previous year.
Earnings jumped 72 percent from three months earlier.
It outpaced earnings reported by its three other rivals, including KB Financial Group.
Woori Finance set aside 288.8 billion won in loan-loss reserves for the third quarter, compared with 924.9 billion won in the second quarter when the group set aside massive provisioning for a corporate overhaul.
The group set aside provisioning of 115 billion won to cover the failure of Woongjin last quarter. The Woongjin failure led its ratio of substandard loans to rise 0.02 percentage points to 2.07 percent, it said.
The group's net interest margin came in at 2.32 percent in the third quarter, down 0.08 percentage points from three months earlier. But its NIM rose from 2.29 percent tallied in the same period of last year.
Woori Bank, the flagship unit of the group, logged a net profit of 457 billion won in the third quarter, down 7.42 percent from the previous year.
Do you know more about this story? Contact us anonymously through this link.