[Korea Market Close] KOSPI closes at 7,034 as crude surges past $100 and refiners decline

The KOSPI ended September 10 at 7,033.92, down 0.25%, after intraday weakness pushed the index down to 6,898.45, a decline of more than 2.17%. The session showed an unexpected disconnect: crude oil breached $100 a barrel, yet refiners fell. S-Oil dropped 6.63%; GS declined 3.44%.

Typically, rising crude lifts refiner valuations on expectations of wider margins. The reversal today reflected profit-taking: refiner stocks had already rallied over recent sessions. LPG distributors, fuel retailers, and lubricant makers moved higher—a split within energy that underscores how crude price moves produce uneven effects across supply chains. Downstream margins compress as feedstock costs rise; distribution and retail benefit from higher volumes and pricing power. One commodity can move the same sector in opposite directions.

KOSPI daily (Naver Finance)

Retail and institutional net buying reversed a 2% intraday decline

The session opened slightly lower at 7,038.85 and bounced to 7,072.79 early, then sold off to 6,898.45 by mid-morning. Recovery began after noon, with the index reclaiming the 7,000 level and finishing at 7,033.92 after a final round of volatility.

Foreign investors drove the decline, net selling KRW 2.48 trillion—the second consecutive session of withdrawals. They also sold 7,086 futures contracts. Retail investors returned to net buying with KRW 380 billion, a six-day reversal. Institutional investors added KRW 432 billion, extending their sixth session of net buying. Other corporates net purchased KRW 1.67 trillion. Foreign outflows of over KRW 2 trillion were absorbed across three domestic buyer categories.

Today marked the combined expiry of futures and options. Expiration days typically produce outsized flows. Whether foreign selling reflected genuine risk aversion or expiration-related position adjustments remains unclear from a single session's data.

9/10 KOSPI net buying by investor type, in billions of won (direct tally; source: InfoStock Market Summary)

Winners: insurers, banks, construction

Nonlife insurers led gains. Hanwha General Insurance surged 6.21%; Hanwha Life rose 4.73%; Hyundai Marine & Fire climbed 2.86%. The catalyst: introduction of the "8-week rule" for auto insurance claims. Under the rule, repair periods are capped at eight weeks, reducing the claims payout burden on insurers and widening underwriting margins. The market repriced immediately on direct earnings visibility.

Banks added modest gains. Woori Financial up 1.49%; KB Financial +0.81%. Builders rose: GS E&C +4.78%; DL E&C +3.33%. Steelmakers like POSCO Holdings and POSCO International eked out small gains. A clear bifurcation emerged: sectors sensitive to domestic rates and activity—insurance, banking, construction—advanced, while export-heavy and commodities-sensitive sectors retreated. The session reflected a defensive shift toward domestically anchored earnings.

GS E&C daily (Naver Finance)

Hanwha General Insurance daily (Naver Finance)

Losers: refiners, batteries, shipbuilders

Beyond S-Oil and GS, battery stocks lagged. LG Energy Solution fell 1.62%; Samsung SDI -2.26%—both had rallied in recent sessions and faced profit-taking today. Shipbuilders slid: Hyundai Samho Heavy Industries -2.16%; Hanwha Ocean -2.95%. Telecom shares S-Oil and SK Telecom underperformed.

S-Oil daily (Naver Finance)

KOSDAQ reversed course, led by semiconductors and robotics

The KOSDAQ index rose 0.79% to 836.92, gaining for a second session. Intraday lows near 813.66 marked a 2% decline—sharper volatility than the KOSPI. Late afternoon strength lifted the index to 839.05. Institutional investors net purchased KRW 1.35 trillion, their first inflow in four sessions, reversing the momentum. Retail sold KRW 270 billion; foreign investors net sold KRW 1.08 trillion. The KOSPI and KOSDAQ finished on opposite sides of unchanged, a reflection of sector rotation: KOSPI faced foreign selling, while KOSDAQ drew institutional demand.

KOSDAQ daily (Naver Finance)

Semiconductor stocks surged. TSE jumped 14.15%; Jusung Engineering +7.02%; Padu +6.59%; SFA Semiconductor +7.24%. Two catalysts emerged: the U.S. Philadelphia Semiconductor Index rose, and TSMC reported August revenue up 53.3% year-over-year, the strongest monthly gain on record. Robotics stocks rallied: Unirobotics +7.54%; Robotis +4.35%. South Korea announced plans to build the nation's first "physical AI robot foundry" in Pohang's Yeongil Bay industrial zone, a supply-chain bet with immediate sector appeal.

TSE daily (Naver Finance)

The core driver: Middle East escalation

Crude's surge traced to the Middle East. U.S. Central Command confirmed strikes on Iranian Revolutionary Guard forces and five Iranian tankers in response to attacks on American vessels. Iran retaliated with missile strikes on a Jordanian base hosting U.S. troops and threatened shipping in Kuwait and Bahrain. The Red Sea remains contested between Saudi Arabia and Iran-backed Houthi forces.

WTI crude rose 3.25% to $96.05 for a seventh consecutive gain. Brent crude climbed 3.36% to $101.21, breaching the psychological $100 barrier. U.S. Treasury long-bond buyback sizes disappointed market expectations, pushing Treasury yields higher and widening risk premiums across asset classes. Korean government bond yields rose, with 3-year yields up 2 basis points and 10-year yields up 5.2 basis points. The won weakened slightly to 1,339.2 per dollar.

The Cody closed limit-up for a fourth consecutive session on announcement of a KRW 30 billion convertible bond issuance and rumors that LG-affiliated Pantos Corporation's CEO Koo Bon-ho may become the largest shareholder. More detail is available in a recent piece. Sempio Foods and Sempio announced buybacks of 29.91% of shares outstanding, both surging to daily limits.

What to watch next

Two data points frame tomorrow. First, whether Middle East tensions deepen further. If crude sustains above $100, import costs and inflation dynamics return to market focus. Second, U.S. inflation data arrives soon. The market closed today with cautious positioning ahead of that release, signaling potential for sharper swings in the sessions ahead.

Foreign selling for two consecutive sessions deserves monitoring. A third day of outflows would challenge domestic support from retail and institutional buyers. Whether they retain capacity to absorb future waves will shape the near-term trajectory. Stocks that have rallied recently—refiners and battery makers chief among them—remain exposed to profit-taking cycles. That structural risk merits attention as well.

This article is provided for informational purposes and does not constitute investment advice or a recommendation to buy or sell any security. Investment decisions and outcomes are the reader's sole responsibility.

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