Four Days with Deleveraging at the Controls — Black Monday's -8.95% and the Seventh Circuit Breaker of the Year, a CPI-Fueled +6.24% Rebound, and a -6.37% Thursday When a Rate Hike, a Leverage Crackdown, and China's Record IPO All Landed at Once
The week AI-chip deleveraging took the controls. KOSPI swung -8.95% (Black Monday, the year's seventh circuit breaker), +0.73%, +6.24% (a CPI-fueled rebound), and -6.37% over four sessions, ending the week down -8.77%. On 7/16 alone, the Bank of Korea's first hike in three and a half years, the single-stock leverage curb, and fear of ChangXin Memory's record IPO converged. Yet the won strengthened to 1,480 through the crash and foreigners bought 2 trillion won on the rebound day — this is not a crash of money leaving, but of positions unwinding. On 7/17, while Seoul rested, the US semiconductor index entered a bear market; Seoul opens Monday carrying that decline.
Reader's Brief — 30-second TL;DR
Intermediate
Why Now
Weekend US-Iran clash near Hormuz plus post-ADR-listing profit-taking -> 7/13 Black Monday -8.95% (6,806.93), first break of 7,000 in two months, seventh circuit breaker of the year, SK Hynix -15.37%, Samsung -10.70%, VKOSPI intraday 97.78 -> 7/14 +0.73% (6,856.83) holds the 6,800 support -> 7/15 cooling US CPI drives +6.24% (7,284.41), buy-side sidecar six minutes after the open, foreigners net buy 2.32T won -> that night in New York, Micron -8% on ChangXin Memory IPO fear -> 7/16 triple blow of a rate hike (2.50% -> 2.75%), the leverage curb (30M won deposit from 8/5), and memory-supply fear: -6.37% (6,820.60), retail buys 4.80T won against 3.06T of institutional selling -> 7/17 Constitution Day closure, and that night the SOX enters a bear market at -20.2% from its peak.
Winners ?? Losers
The week's losers — SK Hynix (-15.37% on 7/13, -11.53% on 7/16), Samsung (-10.70% on 7/13, -8.77% on 7/16), Micron (-13% over 7/15-16, about -31% from its June peak), leveraged retail (344.2 billion won of forced liquidations in July). Held up — the won (1,501.4 -> 1,480.4 through a crash week), foreigners (2.32 trillion won net bought on 7/15), US CPI (confirmed cooling, the week's only antidote). Monitoring — Monday's 7/20 opening gap (pricing the US chip bear market), SK Hynix earnings on 7/22, the asymmetric window before the 8/5 deposit rule, the fight for KOSPI 7,000, the 1,480 won level.
Mon 7/13 — Black Monday -8.95%, the Year's Seventh Circuit Breaker (First Break of 7,000 in Two Months)
To the question New York had answered with +13% last Friday, Seoul replied with -8.95% on Monday. KOSPI closed down 669.01 points at 6,806.93, surrendering the 7,000 line for the first time in two months.
Two triggers — Hormuz profit-taking
Over the weekend, the US and Iran clashed directly again near the Strait of Hormuz, spreading panic across risk assets. On top of that came a catalyst unique to Seoul — with the SK Hynix Nasdaq listing done, profit-taking poured out of the positions that had ridden that event higher. SK Hynix crashed -15.37% to 1.84 million won and Samsung -10.70% to 254,500 won. With the top two names by cap down double digits, the had no way to hold.
A sidecar, then a circuit breaker
A sell-side sidecar fired at 10:34 a.m., and at 1:28 p.m. a circuit breaker halted all trading for 20 minutes. It was the seventh this year — more than half of all circuit breakers in the exchange's entire history have now fired in 2026. KOSDAQ surrendered the 800 line again. The VKOSPI fear gauge jumped 6.04% to close at 94.81, spiking to 97.78 intraday. Once again, mechanical amplified the decline — forced liquidations of margin positions reached 344.2 billion won in July, and the end-of-day rebalancing sales of 2x leveraged products deepened the drop.
The night it spread to New York
That night, Seoul's crash crossed the Pacific. SK Hynix's ADR, starting its first regular session under its permanent ticker, fell -9.3%. To last week's W28 watchpoint — debut heat or durable demand — the first day of regular trading gave a cold answer. 7/13 was the day the exhaustion of a listing catalyst and geopolitics combined to produce the deepest single-day drop of this cycle.
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This report is provided for informational purposes only and does not constitute a recommendation to buy or sell any financial instrument. Investment decisions should be made based on your own judgment and responsibility. The analysis and opinions contained herein are based on information available at the time of writing and are subject to change.