Monthly repayments on W450m loan to jump from 3.04 million to W3.3m as bond yields surge

Global investors are dumping government bonds amid mounting inflation fears, and analysts warn the sell-off could push up lending rates at South Korean banks. As the sell-off drives market rates higher, bank bond yields — which move in tandem — are also rising. With banks needing to issue more bonds than usual this year, upward pressure on rates has intensified. The Bank of Korea has signaled further benchmark interest rate hikes, and some analysts now expect fixed mortgage rates at major banks to exceed 8 percent before year-end, raising concerns about the growing burden on ordinary borrowers and financially vulnerable households.

According to the Korea Financial Investment Association's bond information center, the yield on five-year bank bonds — the benchmark for fixed-rate home loans — stood at 4.498 percent per annum as of Wednesday. The rate had peaked at 4.531 percent on July 24 before easing throughout August, but has since climbed back toward the 4.5 percent mark.

The five-year bank bond yield fell from 3.705 percent at end-2023 to 3.089 percent the following year, then rebounded to 3.499 percent at end-2025. After armed conflict broke out between the United States and Iran in the Middle East in March, it soared to 4.051 percent by end-March and 4.241 percent by end-June.

The recent surge in bank bond yields is largely attributed to rising government bond yields in the United States and other major economies. Analysts say inflation fears have grown on the back of higher oil prices following a renewed outbreak of armed conflict between the US and Iran, while fiscal pressures — including US national debt surpassing $40 trillion — have prompted large institutional investors to sell government bonds broadly. Since bond prices and yields move in opposite directions, increased supply and heavier selling push yields higher.

The yield on the 10-year US Treasury note climbed as high as 4.812 percent during trading on Tuesday (local time), its highest level since November 2023. In the wake of that move, the yield on South Korea's three-year government bond rose to 3.930 percent on Wednesday, up 0.052 percentage points from 3.878 percent the previous day. With the Middle East conflict showing no signs of abating and major technology companies aggressively tapping bond markets for funding, yields are expected to keep climbing.

The domestic financial market is also feeling the strain. The upper end of fixed-rate mortgage rates at the five major banks — KB, Shinhan, Hana, Woori and NH — stood at 7.17 percent per annum as of Wednesday, having dipped from 7.50 percent at end-July to 7.16 percent on Aug. 20 before ticking back up. As bank bond yields rise, domestic lending rates are expected to resume their upward march.

On top of global bond yield pressure, a surge in bank bond issuance compared with last year is also expected to push rates higher. According to the Korea Financial Investment Association's bond information center, the volume of bank bonds maturing from September through year-end totals 89.09 trillion won ($65.1 billion), up 31 percent from 68 trillion won in the same period last year. Banks typically refinance maturing bonds by issuing new ones. With additional funding demand for productive finance initiatives also in the mix, the overall supply of bank bonds in the market is expected to exceed normal levels.

Banking industry officials say these factors could push fixed mortgage rates to 8 percent per annum by year-end. With the Bank of Korea keeping the door open to further benchmark interest rate increases, rates could exceed 8 percent next year as well.

At the current upper-end fixed mortgage rate of 7.17 percent per annum, a borrower taking out 450 million won ($327,000) on a 30-year equal principal-and-interest repayment plan would pay 3.04 million won per month. If the rate rises to 8 percent, monthly payments would increase to 3.3 million won, and to 3.47 million won at 8.5 percent.

Borrowers on variable-rate loans will also face higher interest costs. The COFIX — the benchmark for variable-rate loans that measures banks' monthly funding costs — will reflect the rise in bank bond yields.

Borrowers at non-bank financial institutions are also bracing for higher interest costs. According to the Korea Financial Investment Association, the yield on three-year bonds issued by credit card and capital companies — a key funding cost indicator for specialized credit finance firms — stood at 4.501 percent per annum on Wednesday, up 0.15 percentage points from 4.351 percent at end-July. Unlike banks, these firms have no deposit-taking function, meaning they pass the full increase in their bond yields directly to borrowers through higher lending rates.