A historic rise right after a historic fall. What changed in between? The first-ever consecutive days of circuit breakers (7/28–29) and the biggest gain in 36 years (7/31) occurred in the same week. We lift the hot-air balloon, widen the view back to the highs, and count what actually changed and what did not.
01
What Changed?
7/31 (Fri) close · KOSPI +17.91%, the largest gain in 9,439 trading days since 1990
KOSPI
6,595.45
+17.91%
All-time No.1 · No.2: 2008-10-30, +11.95%
KOSDAQ
719.76
+11.63%
All-time No.2 · No.1: 2026-03-05, +14.10%
SK hynix
1,718,000
+29.95%
KRW 600 short of the upper limit(1,718,600) · High = close · Turnover 14.8tn
Samsung Electronics
262,500
+26.81%
Turnover 12.0tn · KRW 26.8 trillion in just two stocks
It was not a gap-up. The market opened quietly at 5,657.79 (+1.15%) and moved intraday. From the low of 5,629.76 to the high of 6,630.77, it traversed +17.8% in one day. At 09:06, the KOSPI and KOSDAQ both triggered buy sidecars just 1 second apart — each market's first buy sidecar of the year.
The four-day path
Date
KOSPI
Change
Market measures
7/27 (Mon)
6,755.75
+0.97%
—
7/28 (Tue)
6,023.66
−10.84%
Circuit breaker 10:13
7/29 (Wed)
5,663.24
−5.98%
Circuit breaker 12:38 · First-ever 2 consecutive days
7/30 (Thu)
5,593.56
−1.23%
—
7/31 (Fri)
6,595.45
+17.91%
09:06 · Buy sidecar
Three Windows
The same market looks different depending on the reference point. All highs use closing levels.
Basis
KOSPI
KOSDAQ
5 days earlier (7/27)
−2.37%
−5.90%
KOSPI high (6/22 · 9,114.55)
−27.64%
−25.68%
KOSDAQ high (4/27 · 1,226.18)
−0.30%
−41.30%
Using the KOSDAQ high (4/27) as the reference, the KOSPI is nearly unchanged at −0.30%. Over the same 3 months, KOSDAQ fell −41.30%. Indices are averages and conceal the gap. In that period, SK hynix was +32.97% and EcoPro BM −50.12%.
What Did Not Change
Measure
6/22
Current
Change
DDR4 16Gb spot price
$69.750
$84.976
+21.83%
DDR4 8Gb spot price
$35.900
$42.130
+17.35%
DDR5 16Gb spot price
$46.167
$50.967
+10.40%
Semiconductor export prices (June)
—
YoY +168.5%
Verdict: Accelerating / No sign of a peak
Exports (7/1–20)
—
YoY +52.3%
Semiconductors +180.6%
All-industry production (June)
—
MoM +2.3%
Largest since 2020-06
Output-cut announcements
—
None
—
While the KOSPI fell −27.64%, memory spot prices rose 10–22%. DDR5 is at its period high. Our semiconductor-price indicator still reports no sign of a peak. Peaking is visible only in forecasts (Q3 contract prices +13–18%, down from Q2 +58–63%), not in measured prices. Spot prices are DRAMeXchange session averages by quotation date (6/22 → 7/30), separate from contract prices.
What Changed
Measure
6/22
Current
Bank of Korea policy rate
2.50%
2.75% (7/16)
Investor deposits
132.19tn
KRW 104.66tn (−20.83%)
Total margin loans
38.53tn
KRW 32.15tn (−16.56%)
└ KOSDAQ
9.06tn
KRW 6.64tn (−26.71%)
Foreign ownership by market cap
—
36.4% (June / Record)
Chinese DUV lithography equipment
In development
5 units planned this year (7/27)
SK hynix long-term supply agreements
—
Around 10 customers / Up to 5 years (7/29)
Samsung Electronics price targets (7/1–16)
—
249 upgrades vs 323 downgrades
Basic deposit for single-stock leverage
KRW 10 million
KRW 30 million cash (7/31)
02
What Has Been Confirmed Since Yesterday
Items left open in #05 now have observations
1
7/30 margin loans — released today
Total: KRW 33.00tn → KRW 32.15tn (−KRW 0.85tn); KOSDAQ: KRW 6.82tn → KRW 6.64tn (−KRW 0.18tn). Deposits also fell from KRW 109.59tn to KRW 104.66tn (−KRW 4.93tn). The decline was on the day before the 7/31 rule took effect, so cash-deposit requirements may have moved funds — an institutional effect, consistent with #05's warning against misreading early-August indicators. #05 assumed the 7/29 margin balance unchanged and reported intensity at 1.058. Substitute measured credit and it is 1.030.
2
Leverage intensity — 0.923, below the pandemic low
0.980(7/28) → 1.029(7/29) → 1.030 (7/30 observed) → 0.923(7/31). It passed below the pandemic low of 0.948. Decompose the change from 7/29 to 7/31: numerator (margin repayment) −0.027 / denominator (index rise) −0.079. Thus, roughly three-quarters of the change came from price.
3
Foreign KOSDAQ net buying — 4 consecutive days
7/28 +KRW 86 billion(final aggregation; #04/#05's +KRW 86.9 billion was provisional) → 7/29 +KRW 308.2 billion → 7/30 +KRW 248.3 billion → 7/31 +169.7bn.
Weekly total +KRW 670 billion(net buying on 4 of 5 days). Over the same period, foreign KOSPI flows were -62.8bn, effectively unchanged.
4
Weekly flows — institutions were the buyers
KOSPI total, 7/27–31: retail −KRW 5.3809 trillion / Foreign -62.8bn / Institutions +KRW 5.4396 trillion(investment trusts +KRW 2.2017 trillion; pensions +KRW 927.1 billion). On 7/31 alone, foreigners bought +KRW 7.2414 trillion — , the largest single-day net purchase ever. The previous record was KRW 3.14 trillion on 2025-10-02. This was 2.3x. SK hynix accounted for KRW 3.6086 trillion; Samsung Electronics KRW 2.1168 trillion(the net-buying total differs by KRW 21.8 billion from the media aggregate of KRW 7.2196 trillion, likely due to timing and NXT inclusion). Over the week, foreigners effectively bought back what they sold on 7/28–29.
5
KOSDAQ/KOSPI ratio — 0.1091
0.1153(7/30) → 0.1091. Distance to the 10-year low of 0.0994: 9.7%. The KOSPI rebounded more today.
Intensity = KOSDAQ margin loans ÷ (KOSDAQ index ÷ 100) — debt per 100 index points. A decline from less debt differs from one caused by a rising index, even if the resulting value matches. Today's 0.923 divides 7/30 observed margin loans (KRW 6.64 trillion) by the 7/31 closing index. Margin loans are released T+1; the 7/31 figure arrives next business day.
7/29
1.029
6.82tn / 662.68
7/30
1.030
6.64tn / 644.78 Observed
7/31
0.923
6.64tn / 719.76 Provisional
Pandemic low
0.948
2020-03-19 / Passed below
03
What Happened Outside?
Observations outside Korea over the same period
The semiconductor correction began before Korea's
Date
Event
Figure
7/16
TSMC Q2 earnings — weak Q3 margin guidance
Revenue $40.2 billion / Net income +77%
7/17
SOX entered a bear market (from the late-June high)
−20.3%
7/17
TAIEX's largest one-day point decline ever / Record foreign net selling
−6.47%
7/27
CXMT Shanghai listing / Reports of Chinese DUV production
First day +465.82%
7/27~28
ASML cumulative fall over 2 trading days
−12~13%
7/29
SOX low (from late-June high)
−28.7%
7/30
SOX rebound
+8.19%
SOX was already in a bear market on July 17. Ten days before Korea's circuit breakers (7/28–29). Taiwan suffered its record one-day point decline that same day.
Rising Memory Prices Squeeze Device Makers
Apple (7/31 premarket)
−7%
FY26 Q3 revenue hit a record $109.4 billion (+16%), yet shares fell. Surging memory costs and chip supply constraints disappointed next-quarter guidance
Samsung Electronics DX (Q2)
-800bn
Revenue KRW 48 trillion, but an operating loss — rising component costs
Microsoft (7/30)
+15.5%
Market cap rose about $492 billion — its largest 1-day increase Azure +43%; annual revenue first exceeds $100 billion
Amazon AWS (Q2)
+37%
Fastest growth in 18 quarters / Capex $220B
Apple and Samsung Electronics reported the same phenomenon: higher memory prices reduce profits for those who buy and use it. Samsung DX's −KRW 800 billion loss and Apple's guidance disappointment show the same structure on different continents. Meanwhile, 4 hyperscalers' combined 2026 capex is $725 billion, +77% year on year. Alphabet reported its first negative quarterly FCF in about 20 years.
Rates and Currencies
Measure
Value
Notes
US 30-year
5.201% (7/29)
Intraday 5.244% — highest since July 2007
7/9 30-year auction
Award yield 5.058%
Highest award yield since 2007 / Bid-to-cover 2.44x
FOMC (7/28~29)
Held at 3.50–3.75%
9-3 / 3 pro-hike dissenters, most since September 2016
BOJ (7/31)
Held at 1.0%
8-1; Takata proposed a rise to 1.25%
BOJ FY2026 core CPI
2.8% → 2.5%
Lower than April forecast
ECB
6/11 hike → 7/23 hold
Deposit rate 2.25% / Hold was unanimous
USD/JPY (7/30)
158.34
−3%, Largest fall since 2022 / Suspected intervention — Bloomberg estimate: about JPY 8.45 trillion ($53 billion), based on BOJ current-account data(MOF declined comment)
Dollar index (7/30)
Touched 99.87
Lowest since 6/17
This table describes one combined event: the won appreciated to KRW 1,421 per dollar, and intervention drove a sharp yen rebound. KRW per 100 yen had widened all month. It turned for the first time from KRW 877 (7/30 low) → KRW 888. If the weak-yen trade starts unwinding, both the durability of the KRW 800 range and flows into won assets held by Japanese capital face a test.
Markets That Rose in July
Market
July
Notes
Hang Seng
+13.13%
Chinese state investment platforms bought around CNY 60 billion(7/20–21)
Euro Stoxx 50
+1.24%
The only major market in positive territory
S&P500
−0.82%
−3.42% from the period high (7/10)
Nasdaq
−4.16%
−7.00% from the period high
Nikkei
−8.14%
Includes the 7/31 +4.03% rebound
7/28 Kumamoto earthquake(MJMA 7.1, at least 35 deaths) led to an evacuation at TSMC's Japanese subsidiary JASM. JASM is less than 3% of TSMC's total capacity.
04
Other Notable Observations
Newly confirmed figures
1
Foreigners are buying KOSDAQ — two sources agree
FSS June data: KOSPI −KRW 50.979 trillion, versus KOSDAQ net buying of +KRW 1.643 trillion. This week (7/27–31), KOSDAQ foreigners +670bn.
The same direction appears in two different compilations for a second month. We keep watching when capital returns to the neglected KOSDAQ. This is an observation added to that watch.
2
Europe and the US were June's sellers
UK −KRW 32.2 trillion(the largest), US −KRW 23.182 trillion, Luxembourg −KRW 4.269 trillion. By contrast, Asia net bought +KRW 2.552 trillion. Regions moved in opposite directions.
3
KRW 49 trillion sold, yet record ownership
June foreign net selling of listed stocks was KRW 49.336 trillion(a record, 6 consecutive months), yet holdings rose to KRW 2,908.6 trillion, up +KRW 56.33 trillion from the prior month. Market-cap ownership reached a record 36.4%. Valuations rose faster.
4
Crypto moved the other way
While the KOSPI was −27.64% from 6/22, Bitcoin was +2.38%(63,232 → 64,736). ETH/BTC rose +9.87%; Bitcoin funding rose from 0.0066 to 0.0100.
05
What to watch
Dates When Observations Face a Test
8/1 (Sat) 09:00
Final July trade data The 7/1–20 preliminary figures showed exports +52.3%, semiconductors +180.6%. Will the full month hold?
8/4 (Tue) 08:00
July consumer prices June 3.2%. The BOK raised its rate to 2.75% on 7/16.
Early August Monthly
July semiconductor export prices — first observed test of peaking Latest: June (YoY +168.5%; verdict accelerating / no sign of a peak). July will provide the first check of whether peaking appears in measured prices rather than forecasts.
8/7 (Fri) 21:30 KST
US July jobs report Whether it strengthens the case of the FOMC's 3 pro-hike dissenters.
8/19 (Wed) Takes effect
Tighter deviation-ratio controls for single-stock leverage
Early next week Weekly observation
PortWatch weekly update — Red Sea S2 verdict
The #04 test applies to this update: S2 confirmed if Yanbu (2.16mb/d) and Bab-el-Mandeb (8.4 vessels) hold at blockade-week levels; a reversal means noise. Since the Iran ceasefire ended, Brent has retained a premium at $89–92.
Mid-August Monthly
FSS Foreign Investors' Securities Investment Trends, July
In June, the UK and US sold while Asia bought. This will show which regions bought back in July.
8/26 (Wed) Earnings
NVIDIA earnings
Undecided —
20% aggregate investment cap for single-stock leverage / Next Monetary Policy Board meeting Decided at the 7/29 F4 meeting, but the effective date and legal form were not announced.
