South Korea's biggest banks are making more money than ever - and their regulators are pleading with them to stop lending to one of the rich world's heaviest household debt burdens.

The four financial holding groups that dominate Korean finance - KB, Shinhan, Hana and Woori - booked a combined net profit of KRW11.34 trillion ($8.2bn) in the first half of 2026, up 9.8% y/y and a record, on results reported on July 24. A market rally and swelling fee income did much of the lifting, even as the day job of lending to households ran into a regulatory wall.

The Korea Times noted the quartet “face mounting headwinds despite solid profits”, from a won trading above 1,500 to the dollar to a revised banking law that bars lenders from padding loan spreads with administrative costs.

The profits matter because of how they were made. Korea has quietly built one of the rich world's heaviest debt burdens - household borrowing runs at about 92.7% of GDP, near the top of the OECD - and the earnings now rolling in were built on the very mortgage boom the authorities are scrambling to deflate.

The brakes go on

Through July the country's biggest lenders came close to a household-loan shutdown. Hana Bank halted mortgage and jeonse (key money) applications through brokers from July 10; Shinhan Bank shut its broker channel two days earlier; and KB Kookmin Bank cut its maximum home-purchase loan in the capital region to KRW300mn from KRW600mn - the first commercial bank to set a ceiling below the government's June 2025 curbs.

The squeeze followed a surge in borrowing. Household loans excluding policy lending at the five biggest banks - KB Kookmin, Shinhan, Hana, Woori and NH NongHyup - stood at KRW648.36 trillion in early July, and every institution that breached its annual growth target pulled up the drawbridge.

Regulators have kept the pressure on. A Bank of Korea survey put banks' lending-attitude index at -7 for the third quarter, a sixth straight quarter of tightening, while retail borrowing costs climbed with it: average mortgage rates hit a 31-month high of 4.36% in June after the central bank raised its benchmark by 25 basis points to 2.75%, its first hike in three and a half years.

A mountain of household debt

Cooling the debt has proved maddeningly hard. Household lending at the top five banks jumped to KRW765.73 trillion in April, the sharpest monthly rise in half a year, as Seoul's deep-rooted appetite for property outran speculative-zone designations and tighter caps alike.

Choke off one channel and the money finds another. As bank credit tightened, borrowers piled into peer-to-peer platforms to fund stock bets, pushing outstanding P2P stock loans up 71.5% to KRW898.3bn by the end of June and prompting the Financial Services Commission to slap on emergency caps. Deposits have drained out of savings banks and into a buoyant equity market, leaving the authorities juggling debt, property prices and a retail-trading frenzy at once.

Project finance, the slow burn

Beneath the household story sits an older sore: real-estate project finance. Korea's PF loans reached KRW132.2 trillion, with almost two-thirds held by non-bank lenders, and the strain has fallen hardest on the smaller institutions. Savings banks' PF non-performing loan ratio climbed to 11.5% by mid-2024 from 3.4% at the end of 2021, and defaults since have forced them to cut deposit rates and shed funds.

Deposits at the savings banks fell for the first time in six months late last year as the fallout spread, a reminder that the property cycle the big groups largely dodged is still smouldering at the edges of the system.

Record profits, and a value-up push

For the four majors, though, 2026 has been a banner year. KB Financial led with a net profit of KRW3.88 trillion, Shinhan followed on KRW3.44 trillion, Hana made KRW2.4 trillion, up 4.4%, and Woori KRW1.61 trillion, up 3.7%, lifted by fee income and non-bank arms as much as by lending.

The windfall is flowing straight to shareholders. Riding Seoul's “value-up” campaign to close the country's chronic equity discount, KB and Shinhan each earmarked KRW700bn for buybacks and cancellations alongside higher dividends, with Hana and Woori adding their own. The catch is that the tailwinds are fading: a won stuck above 1,500 to the dollar is inflating risk-weighted assets, and the new banking law will thin margins in the second half even with rates higher.

The groups are also spending to defend their franchises. All four are racing to bolt artificial intelligence onto their cyber-defences, from Woori's Xint penetration-testing platform to Hana's security framework and Shinhan's generative-AI incident response, as a heavily digitalised system makes Korea a prime target for automated attacks.

The internet banks close in

The sharper long-term threat comes from the challengers. KakaoBank, the largest of Korea's three internet-only lenders, posted a record first-half net profit of KRW328bn, up 24.4% y/y, with 27.63mn customers - more than half the population - and a loan book of KRW48.2 trillion, nearly half of its recent growth coming from lending to sole proprietors and small firms the big banks have long overlooked.

Its ambitions run past the peninsula. Having entered Indonesia and Thailand, KakaoBank is making Mongolia its third overseas market, exporting an alternative credit-scoring model built on non-financial data. “We will transplant our alternative credit valuation model... to local financial institutions,” chief executive Yun Ho-young said, casting the push as “inclusive finance” for borrowers the incumbents price out.

K Bank and Toss Bank, the other two digital lenders, are chipping away from the same direction, courting younger and thinner-file customers with slicker apps. None is about to topple KB or Shinhan, whose scale and record profits remain in a different league.

Yet the shape of the challenge is clear enough. The big four are richer than they have ever been and returning cash hand over fist, while the state leans on them to stop feeding a household-debt pile that will not shrink, project finance keeps smouldering at the margins, and a clutch of app-based upstarts quietly widens its share of the next generation of borrowers. Managing the windfall may prove easier than managing what comes after it.