KOSPI -7%, KRW Breaks 1,500: The Day the Iran War Rocked Korea's Stock Market

March 3, 2026 will go down as a day for the history books in Korean financial markets. KOSPI (Korea Composite Stock Price Index) went into freefall the moment trading opened, and the losses only deepened through the close — the index finished at 5,791.91, down 452.22 points (7.24%) from the previous session.¹ It was the largest single-day point drop ever recorded. In percentage terms, it was the steepest decline since the “Black Monday” of August 2024 (-8.77%), when the unwinding of yen carry trades sent markets reeling — and the 14th-largest single-day drop in KOSPI history overall.² The source of all this turmoil was singular: a Middle East war ignited by U.S.-Israeli airstrikes on Iran.

Why Korea Got Hit Hardest: The Vulnerability of an Energy Artery

Major indexes in the U.S., Japan, and Europe all fell, but Korea’s plunge was in a class of its own — the steepest decline among Asian markets. The reason lay in a structural vulnerability baked into the Korean economy itself.

Korea imports 70.7% of its crude oil from the Middle East, and 95% of that Middle Eastern oil transits through the Strait of Hormuz.³ Some 20–30% of global crude oil trade and roughly 20% of global LNG trade passes through this 55-kilometer-wide chokepoint. And Iran, in response to the outbreak of hostilities, declared a blockade of the Strait of Hormuz. For a country that depends on imports for virtually all of its energy, this was no mere diplomatic bluster — it was an existential alarm that the arteries of the economy might be severed.

Layer on top of that Korea’s export-heavy industrial base in energy-intensive sectors like semiconductors, automobiles, and petrochemicals, plus an open capital market where foreign money moves freely in and out, and you get a market that functions as an amplifier for global shocks. On a day when U.S. markets were down just 0.1% and Japan fell 3%, Korea plummeted 7%.⁴

Deputy Minister of Trade, Industry and Energy Moon Shin-hak stated that “given that a substantial portion of the oil and gas we import passes through the Strait of Hormuz, we need to closely monitor the potential for expanded risks to oil prices and maritime transport,” and announced the activation of a joint inter-agency response task force led by the Deputy Prime Minister for Economic Affairs.⁵ The government recognized the gravity of the situation.

Anatomy of the KOSPI Plunge: The 6,000 Line Breaks

When trading opened on March 3, KOSPI was already hundreds of points below the previous close. At one point during the session, it attempted a bounce back toward the 6,180 level — but once foreign selling resumed in earnest, the decline accelerated rapidly.⁶ The 6,000 mark collapsed almost instantly, and the index kept sliding right up to the close. The KOSDAQ also fell sharply, dropping 55.08 points (4.62%) to finish at 1,137.70.

The heaviest-weighted stocks led the index lower. Samsung Electronics, Korea’s largest company by market cap, tumbled 9.88%. The 200,000-won threshold was briefly breached during the session, and Samsung alone wiped out tens of trillions of won in market capitalization in a single day. SK Hynix fell even harder — down 11.5%, breaking through the symbolic 1,000,000-won level.⁷ The simultaneous collapse of Korea’s two semiconductor titans — once celebrated as “200,000-won Samsung” and “1,000,000-won Hynix” — hit investors with a shock bordering on panic.

Of the 935 stocks listed on KOSPI, 842 fell. The market effectively collapsed across the board. The KOSPI Volatility Index (the so-called “fear gauge”) hit an all-time high, and the total market capitalization wiped out that day reached 377 trillion won — the largest single-day destruction of value on record.⁸

Industries expected to absorb the direct blow of surging energy import costs — aviation, petrochemicals, and automotive — all posted steep losses, dragged down by the spike in global oil prices that accompanied the outbreak of war. Refining stocks bucked the trend somewhat, with some names rising on expectations of inventory revaluation gains, but the overall market mood was one of indiscriminate selling.

What 1,505 Won Means: Seventeen Years, Gone in a Flash

During regular trading hours on March 3, the USD/KRW exchange rate fluctuated in a range with 1,470 won as the upper bound. But when the after-hours market opened, the picture changed dramatically. A cascade of additional bad news from the Middle East triggered an explosion of dollar buying, and by 12:22 a.m. on March 4, the won had surged to 1,505.8 won per dollar.⁹

Breaking through 1,500. The significance of that figure went far beyond the number itself. The last time the won had traded at this level was March 12, 2009 — the depths of the global financial crisis. The era when the collapse of Lehman Brothers had sent the entire global financial system into a panic. The won hadn’t been pushed to this point in 17 years.¹⁰

The dollar is the “king of safe havens,” and it shines every time war breaks out. When investors dump risk assets and flee to dollars, emerging-market currencies like the won are always first in line to get sold. In Korea’s case, fears that the surge in energy import costs caused by the war would worsen the current account balance accelerated the won’s weakness even further. It was a double shock: import prices rising at the same time the won’s value was falling.

Since 2009, the Korean economy had grown accustomed to exchange rates in the 1,000–1,300 won range. There were times when even the 1,400 level was treated as an emergency. And now here was 1,505 won. That single number said everything about the scale of risk the market believed it was facing.

The Defense and Shipping Paradox: Sectors That Found Opportunity in War

On a day when the broader market was in ruins, some sectors soared. The defense and aerospace sector averaged +16.97% on the day, while shipping gained +15.67%.¹¹ Greed blooming in the middle of fear.

The surge in defense stocks was driven by the immediate associations conjured by the word “war.” The U.S.-Israeli airstrikes on Iran unleashed a wave of expectations for increased defense spending around the world. Korean defense names were lifted specifically by prospects of NATO nations strengthening their own defensive capabilities, and by anticipation of rising weapons demand as security tensions deepened across the Middle East and East Asia.

Hanwha Aerospace spiked as much as 24.88% intraday, trading at 1,492,000 won.¹² LIG Nex1 surged 27.11% to close at 647,000 won, hitting a new all-time high. Hanwha Systems gained +19.98%, Hyundai Rotem +10.41%, and Poongsan +11.40% — defense-related stocks across the board posted double-digit gains.¹³

Shipping stocks surged on a different logic. If the Hormuz blockade became a reality, demand for alternative routing around the Middle East would explode, driving sharp increases in freight rates. Investors still remembered how ocean freight rates spiked during the Ever Given grounding in 2021 and the Red Sea crisis of 2024. HMM (011200) rose +14.75%, Pan Ocean gained +17.42%, and Korea Line rocketed an astonishing +25.81%.¹⁴

Analysis emerged that war risk insurance premiums were already beginning to surge. Some estimates suggested premiums for tankers transiting Hormuz could rise as much as sevenfold compared to peacetime.¹⁵ If the route closes, shipping companies take longer detours — and as voyage times and fuel costs increase, freight rates follow. That was the mechanism shipping investors were betting on.

The Foreign Exodus: The Weight of 5.1731 Trillion Won

The most striking supply-and-demand dynamic of the day was the massive flight of foreign capital. Foreign investors net-sold 5.1731 trillion won on the main board — the second-largest single-day net selling on record.¹⁶ The top spot belonged to February 27, just two trading days prior, at 7.0812 trillion won. It was the second consecutive session of record-breaking net foreign selling, and cumulative net selling since the outbreak of the Iran war had reached 21 trillion won.¹⁷

The stock foreigners sold most aggressively was Samsung Electronics. In the days since the war began, Samsung alone saw 9.2893 trillion won in net selling, while SK Hynix shed another 3.3812 trillion won.¹⁸ More than 12 trillion won fled from just those two semiconductor names.

Institutions also tilted toward selling, with 889.5 billion won in net outflows, adding to the index’s decline. Retail investors alone were buying the dip — but they were no match for the combined selling force of institutions and foreigners.

Behind the foreign exodus lay structural factors. Korean equities carry high foreign ownership rates and are particularly vulnerable to the global risk-off dynamic, in which geopolitical crises trigger broad liquidation of emerging-market assets in favor of dollars and safe havens. And at the core of the Korean market, semiconductors are one of the most economically sensitive sectors — the first to get sold as recession fears grow. The same pattern played out during the 2009 financial crisis and the 2020 COVID shock: foreigners were the fastest to exit Korean markets.

Looking Ahead: Three Scenarios at the Fork

The direction of the war would determine the path markets would take — and there were roughly three scenarios to consider.

Scenario 1: Limited Strike Followed by Early Negotiations

Most analysts framed the airstrikes less as a prelude to full-scale war and more as a military option designed to apply pressure in nuclear negotiations.¹⁹ Given Iran’s limited retaliatory capacity and the U.S.’s stance against committing ground troops, an early ceasefire and resumption of talks remained plausible. If that scenario materialized, the lifting of the Hormuz blockade and stabilization of oil prices could set the stage for a sharp KOSPI rebound. The government’s announcement that it held strategic reserves of crude oil and petroleum products equivalent to 208 days of consumption²⁰ signaled that short-term supply shocks could be cushioned.

Scenario 2: Prolonged War of Attrition

If the war dragged on for months or longer, markets would likely go through a painful process of finding a new equilibrium. Structurally higher oil prices, renewed inflation, and global supply chain disruption would be likely consequences. Korea’s energy import bill would swell significantly, the trade balance would deteriorate, and the won could face additional downward pressure. Defense and shipping stocks would maintain their strength, but the broader market could slip into a prolonged downturn.

Scenario 3: Collapse of the Iranian Regime or Full-Scale War

The most extreme scenario. If the U.S. pivoted to an all-out war aimed at toppling Iran’s theocratic government, or if Iran struck a third country in or around the Persian Gulf, the shock to global supply chains would be of an entirely different magnitude.²¹ Further sharp declines in KOSPI could not be ruled out.

Which scenario would materialize would determine whether defense stocks had further room to run, how sustained the rise in shipping rates would be, and at what level the won would eventually stabilize. What was already clear was that the sheer sensitivity of Korean markets to the smell of gunpowder from the Middle East had laid bare, in the starkest terms, the structural energy vulnerability at the heart of this economy.

March 3 ended. But the war did not.