Long-term rates are, in essence, the price tag on what an economy must pay for the future. The U.S. 10-year Treasury yield crossing 4.8% on the afternoon of September 2 means that price tag has been visibly repriced over the past several months. On the same day on the Korean exchange, the KOSPI slipped by roughly 1% from the prior close, while the won/dollar rate pushed past 1,380 won and once again tested the vicinity of its annual high. A day on which both figures moved together is a day that reinforced the lesson that rates and the exchange rate do not move in isolation.
This was no accidental event. The chain in which Middle East geopolitical tension pushes oil prices higher, oil gains reignite inflation expectations, and those expectations reshape the long-end versus short-end spread on the yield curve had been repeating all summer. The first session of September was simply the day that structure became fully visible at once.
A Week of Developments and the September 2 Threshold
In New York during the final week of August, Federal Reserve officials spoke in rapid succession. On the 28th, Governor Candless stated that cutting rates before inflation reached target would be premature, and on the 29th, Vice Chair Bowles signaled that the policy-rate path warranted reexamination. Those remarks carried the 10-year yield into the early 4.6% range over the weekend, and by Monday before the Seoul open, foreign short positions in futures had already widened.
The KOSPI opened near the 2,620 mark at 9:00 a.m. on September 2. Roughly an hour after the open, as the 10-year yield crossed 4.7%, the pace of net foreign selling accelerated, and shortly after the yield broke 4.8% around 1:20 p.m., the KOSPI slipped into the 2,580s. The KOSDAQ retreated below the 780 level, and at the same time the CME FedWatch probability of a September rate hold climbed above 92%.
The exchange-rate move was even sharper. The spot won/dollar rate rose to 1,385 won intraday, marking its highest level since August 14, while the offshore December-maturity USD/KRW swap spread widened by more than 15 basis points, indicating that short-term funding costs were rising in real terms. The Seoul FX close in the 1,382-won range represented a step up from the 1,350-to-1,365-won band that had defined August.
Subtle shifts were also visible in the bond market. The 30-year yield rose to 4.93%, bringing its spread over the 10-year back into positive territory after a 2-basis-point inversion the day before, while the 5-year sat at 3.92% with an 88-basis-point gap to the 10-year. The curve shifted upward overall, compressing into a single day the signal that long-term inflation expectations had not yet fully settled.
Oil, Rates, and Structural Vulnerability
The direct trigger was the resumption of military confrontation between Israel and Iran. Following Iran's drone strikes on August 25, Israel's retaliatory air campaign on the 31st drove Brent futures from the high-$70s to the mid-$80s per barrel, an increase of nearly 8% in eight days. Higher oil feeds directly into the energy component of the U.S. CPI and undermines the path the Federal Reserve had built on the assumption of "relatively low inflation."
Beneath the surface lay a structural factor that had been accumulating. In the first half of 2024, the U.S. 10-year yield remained in the 4.1-to-4.5% band, keeping the real rate near 2% and creating an environment that gradually compressed consumer spending and corporate capital expenditure. The overlay of a Middle East oil shock only strengthened the Fed's rationale for maintaining a rigid, "data-dependent" posture.
The domestic structure carries its own vulnerabilities. The stretch during which the real yield on won-denominated assets trailed the real rate on U.S. Treasuries lengthened over the course of 2024, pushing foreign bond and equity portfolios to structurally reduce their Korea allocation. As of the end of August, cumulative net foreign selling of Korean equities had exceeded 12 trillion won, reaching the largest level since September 2022, and the additional 800 billion won of net selling on September 2 alone deepened that trend.
The Bank of Korea's room to respond is also at its limit. The 3.50% policy rate sits 175 basis points below the Fed's 5.25-to-5.50% range, and that gap itself functions as a constant source of won-selling pressure. As long as the Fed does not cut, removing the downside stickiness in the exchange rate remains difficult, and the fact that the August FOMC dot-plot upper bound held at 5.75-to-6.00% signals that this structural pressure will carry into the fourth quarter.
Behind the Numbers: A Sector-by-Sector Picture
The sector-level moves in the KOSPI on September 2 illustrated a clear binary split. Banking stocks rose 2.3% from the prior session and insurance stocks gained 1.8%, as capital rotated into financials whose net interest margin pressure eases in a 4.8% 10-year environment. On the other side, electric-and-gas utilities fell 3.1% and construction stocks dropped 2.7%, showing that even defensive sectors took a direct hit from the rate move.
Semiconductors were mixed. Samsung Electronics fell 1.2% amid foreign selling, while SK Hynix managed a modest 0.4% decline as HBM3E supply expectations provided a cushion and 2-nanometer foundry order news partially offset the rate shock. The secondary battery sector as a whole dropped in the 2.5-to-4% range, laying bare its high-rate-sensitivity, growth-equity character.
Even among export names with high exchange-rate sensitivity, differentiation was evident. Auto stocks—Hyundai Motor up 0.8%, Kia up 1.5%—gained as a weaker won translated into FX benefits, while airlines and shipping lines with heavy raw-material import dependence fell in the 2-to-3% range. The same won depreciation produced winners and losers depending on each company's revenue structure.
In the bond market, the 3-year yield rose 2 basis points to 3.68% and the 10-year climbed 5 basis points to 3.72%, yet the 3-to-10-year spread held steady at 4 basis points. The 30-year moved up to 3.81%, indicating relatively greater volatility at the long end, and the consensus that "short-end rates are set by the Fed while long-end rates are determined by oil and structural inflation expectations" was reaffirmed.
Fall 2022 and Fall 2024
In September 2022, the U.S. 10-year yield traded in the mid-4.4% range before touching 4.6% by month-end, and the won/dollar rate broke the 1,400-won level. The surface numbers look similar, but the structural difference is clear. In 2022, inflation was running above 9% in a super-surge phase, whereas in 2024 core inflation had moderated to around 2.8% and oil-driven volatility was layered on top.
The intensity of the equity-market response differed as well. In September 2022 the KOSPI posted a monthly loss of 5.2% and fell a further 3.1% in October, leaving four consecutive months of negative returns. The September 2, 2024 dip was in the neighborhood of 1% for the day, closer to a pause after the KOSPI's +2.8% gain for all of August, and the key difference is that valuations relative to prior peaks were more favorable than in 2022.
There is also a shared warning. In both episodes the perception that "the Fed is no longer accommodative" served as the turning point. Just as the 10-year yield surged 40 basis points in two weeks after Powell declared the "defeat of inflation" at the July 2022 Jackson Hole meeting, if the Fed in 2024 begins treating Middle East oil pass-through as a "signal of inflation-expectation re-anchoring," the back end of the yield curve risks being pushed higher again.
The exchange-rate story reads almost in reverse. In 2022 the Bank of Korea hiked three times in a row before the 1,400-won breach came in October, while in 2024 the 1,380-won range reappeared immediately after the 25-basis-point cut in August. "A spike despite hikes" and "a spike right after a cut" look alike on the surface but operate through different internal mechanisms, and the direction in which that difference plays out in the fourth quarter is the critical question.
The Next Ten Days and the October FOMC
The most urgent variable is the scope of the Middle East conflict. Whether Iran escalates to a direct threat against the Strait of Hormuz or the exchange remains confined to localized drone-and-missile exchanges will determine whether Brent holds the $80 line or drifts toward $90. If the $90 scenario materializes, the probability of a December Fed cut falls into the 40s, and the 10-year yield faces the risk of re-entering the 4.9-to-5.0% range.
Domestically, the September 13 Monetary Policy Committee meeting is the decisive fork. The core question is whether the BOK holds at 3.50% while hinting at a further fourth-quarter cut, or extends its hold posture in the face of Middle East uncertainty. If the committee pushes through a cut on the logic that "oil pass-through has not yet been confirmed," the widening rate gap raises the risk of pushing the exchange rate into the 1,400-won range.
On the U.S. side, the September 18 FOMC and the September 26 CPI print are consecutive checkpoints. Whether the Fed classifies the Middle East oil rise as a "temporary exogenous variable" or accepts it as a "signal of inflation-expectation re-anchoring" will set the direction of the October rate path, and if the August employment report released on September 6 shows wage growth at or above 3.8%, the judgment is likely to lean toward the latter.
Within the Korean equity market, the second-quarter earnings season disclosed at the end of September can serve as a buffer that absorbs the rate shock. Operating-profit consensus for the auto, semiconductor, and battery sectors has already been revised downward since late August, so even a single print that beats consensus could create a structure in which the rate burden is offset by earnings momentum rather than by valuation alone. Tracking how that 4.8% figure changes the numerator and denominator of corporate earnings—rather than reacting to the number in isolation—is the most disciplined way to read the market's direction into October and beyond.
Comments
Post a Comment