An Index Held Up, Every KOSDAQ Top 10 Constituent Fell
KOSPI +0.23% · second straight gain · recovered after falling as much as -1.28% intradayThe opening pressure came from higher oil prices and U.S. yields after renewed U.S.-Iran clashesThe rebound came not from individuals, foreigners or institutions, but from Other Corporations · overnight strength in U.S. semiconductors and record-high August semiconductor exports also supported the two mega-cap chip namesKOSDAQ -1.56% · every constituent of the KOSDAQ Top 10 Index fell
The index was defended, but risk appetite did not return.
MARKET PATH / 01
Low Just After the Open; Direction Firmed in the Afternoon
When direction changed, and what was working at the time
KOSPI · 09:00-15:306,784.29 lower open → 6,732.47 low just after the open → two morning pullbacks → afternoon advance → 6,835.80 close
OPEN6,784.29-0.52%
HIGH6,857.35+0.55%
LOW6,732.47-1.28%
CLOSE6,835.80+0.23%
THE READ
The lower open was driven not by domestic news, but by Middle East developments carried over from the weekendThe first signal was that the low came just after the open and was not broken againTwo morning pullbacks showed that the buying side did not settle the market in one moveBy the afternoon, direction had firmed at the top of the market-cap stack · index gains and market breadth were not moving togetherThe defining feature of the path was KOSPI and KOSDAQ finishing with opposite signs
OPEN · MORNING
Low Just After the Open, Then Two Pullbacks
Opened at 6,784.29, 35.73 points below the previous closeFell to 6,732.47 just after the open, setting the session lowRebounded to around 6,845 near 10:00, then slipped back toward 6,762 around 11:30A low-and-rebound cycle repeated once during the morning
AFTERNOON
Advance After 13:00, One Pullback Around 14:00
Reclaimed 6,800 after noon and climbed toward 6,845 around 13:20Pulled back to around 6,790 near 14:00, then regained directionThe pullbacks were shallower than in the morning
CLOSE
Closed Near the High; KOSDAQ Stayed on the Other Side
Set the high at 6,857.35 around 15:00 · recovered 103.33 points from the low and closed at 6,835.80At the same time, KOSDAQ only trimmed part of its decline from the 815.52 low to 821.25The index sign and the spread of gains inside the market diverged
Direction line traced from the Naver Finance KOSPI intraday chart. Open, low, high and close are confirmed values; the path between them is an approximation drawn from the intraday chart.
WHY / 02
What Pressured the Morning · What Supported the Afternoon
Only the catalysts that actually explained the day's direction
01
The Early Drop Came From Oil and U.S. Yields After Renewed U.S.-Iran Clashes
A U.S. strike on an IRGC base on Larak Island in the Strait of Hormuz and Iranian retaliation sent international oil prices sharply higherHigher oil revived inflation concerns, pushing the U.S. 10-year Treasury yield to 4.758%Risk-asset pressure pushed KOSPI to its intraday low just after the open
-1.28%KOSPI intraday low · vs. previous close
View evidence
Aug. 31 U.S. session: WTI $85.76, +2.83% · Brent $90.49, +2.71%
U.S. military struck an IRGC base on Larak Island; Iran retaliated against U.S. bases in Jordan and the UAE
U.S. 10-year yield 4.758% · roughly +3.8bp from about 4.72% on Aug. 28
CME FedWatch September 25bp hike probability near 62% · rose from 35.4% to 59.7% after Jackson Hole on Aug. 28, then moved higher again
Korean refiners rose · S-Oil +5.00%
KOSPI Insurance +2.15% · Financials +1.52% · treated as relative strength in a rising-rate backdrop, not as a single-cause move; KB Financial was -1.21% within the same broad group
02
Mega-Cap Semiconductors Were Supported by Overnight U.S. Chip Strength and Record August Exports
The U.S. semiconductor index and major chip names rose together in the Aug. 31 session, released at 09:00, reached $46.65bn · +209% year on year · an all-time highSamsung Electronics and SK hynix supported the lower end of the index and became the core of the afternoon rebound
+209%August semiconductor export growth · Ministry of Trade, Industry and Energy
View evidence
Aug. 31 U.S. session: Philadelphia Semiconductor Index 11,535.1 · +0.57% · Nvidia +1.48% · Micron +2.77%
August exports $98.25bn · +68.7% year on year · third-highest monthly total on record
Semiconductors $46.65bn · above $40bn for a third straight month · non-semiconductor items +20%
Trade surplus $34.75bn · above $30bn for a third straight month
Samsung Electronics KRW 261,000, +0.38% · SK hynix KRW 1,693,000, +1.14% · see MONEY for the flow structure in the two names
MONEY / 03
Three Groups Sold KRW 1.6657tn; Other Corporations Took the Other Side
The investors that actually moved today's index
OTHER CORPORATIONS · KOSPI CASH
+KRW 1.6657tn
The figure matched the combined KOSPI net selling by individuals, foreigners and institutions · the index rose on a day when all three groups soldThe opposite side in Samsung Electronics and SK hynix alone totaled KRW 1.5914tn · closing commentary cited treasury-share purchase demand from both companies as a major backdrop · this report does not treat the entire amount as buybacks were net buyers for a 10th consecutive trading dayKOSPI turnover fell roughly 30% from the previous session · an index gain did not mean trading activity had recovered
SK hynix · opposite side+KRW 1.0739tn
Samsung Electronics · opposite side+KRW 517.5bn
Programs · Detailed Flows
KOSPI program-KRW 320.1bn
-KRW 296.3bn
Arbitrage program-KRW 23.8bn
KOSDAQ program-KRW 187.6bn
Vs. the previous session · reversed from -4.00 backwardation to +2.85 contango · cash 1,075.30 · futures 1,078.15 (2609 · expiry 2026-09) · cash and futures close at different times, so the closing gap is not used as directional evidence
Cross-check · KRW 539.8bn individual + KRW 491.9bn foreign + KRW 634.0bn institutional = KRW 1.6657tn · equal to the closing aggregate for Other Corporations net buying Two-stock opposite side · SK hynix KRW 1.0739tn + Samsung Electronics KRW 517.5bn = KRW 1.5914tn · reverse-calculated from the three groups' stock-level net flows, so the opposite side may include Other Foreigners and government/local-government accounts in addition to Other Corporations · previous session KRW 1.5454tn Flow concentration · individual sell TOP1 55.6% / TOP5 79.2% · foreign buy TOP1 23.4% / TOP5 40.6%, sell TOP1 13.6% / TOP5 32.8% · institution sell TOP1 17.0% / TOP5 35.4%, buy TOP1 9.0% / TOP5 32.0% The concentration denominator is the absolute sum of stock-level net sells or net buys for that investor group, not the group's market-wide net amount Individual net buys · LG Innotek +KRW 143.6bn · Samsung Electro-Mechanics +KRW 131.6bn · LG Electronics +KRW 52.6bn · LG Innotek close KRW 590,000, -8.10%; it had risen +5.07% on the previous session's MSCI Korea inclusion effective date Individual net sells · SK hynix -KRW 1.0012tn · Samsung Electronics -KRW 247.8bn · SK Innovation -KRW 71.1bn Foreign net buys · SK hynix +KRW 166.8bn · SK Square +KRW 45.6bn · SK Innovation +KRW 36.6bn Foreign net sells · Samsung Electronics -KRW 184.5bn · LG Innotek -KRW 86.0bn · Samsung SDI -KRW 62.7bn Institution net buys · Samsung SDI +KRW 44.6bn · SK Innovation +KRW 36.1bn · Shinhan Financial Group +KRW 34.0bn Institution net sells · SK hynix -KRW 239.4bn · Samsung Electronics -KRW 85.2bn · Samsung Electro-Mechanics -KRW 74.3bn KOSDAQ · individual +KRW 433.7bn · foreign -KRW 151.4bn · institution -KRW 275.1bn · these are finalized KRX figures; closing-news aggregates differ (individual +KRW 518.1bn · foreign -KRW 226.7bn · institution -KRW 286.3bn), so the two sets are not mixed Five-session cumulative KOSPI flows, Aug. 26-Sep. 1 · individual -KRW 4.42tn · foreign -KRW 1.97tn · institution -KRW 1.67tn Turnover · KOSPI KRW 17.48tn (75% of 5-day average; 68% of 20-day average) · KOSDAQ KRW 4.59tn (92%; 77%) · previous KOSPI KRW 26.04tn, about a 33% decline on finalized KRX data; closing-news totals imply roughly 30%, so the main text uses only the approximate decline rate · KOSPI KRW 1.86tn, 7.5% of turnover · KOSDAQ KRW 0.43tn, 7.8% · SK hynix KRW 540.5bn (9.1%) · Samsung Electronics KRW 375.7bn (7.5%) · LG Innotek KRW 85.5bn (26.0%)
SECTOR / 04
Where It Was Strong · Where It Was Weak
Today's distribution of strength and weakness, not a ranking table
Relative strength in selected KOSPI large-cap value areas; broad weakness in KOSDAQ. The KOSDAQ Top 10 Index () fell 3.04%, with all 10 constituents down · identically named sectors diverged by market · Distribution: KOSPI +2.98% vs. KOSDAQ -2.49% · Financials: KOSPI +1.52% vs. KOSDAQ -2.77%
STRONG
Distribution · KOSPI+2.98%
Insurance · KOSPI+2.15%
Financials · KOSPI+1.52%
Electric & Gas Utilities · KOSPI+0.92%
WEAK
Construction · KOSPI-3.50%
Financials · KOSDAQ-2.77%
Distribution · KOSDAQ-2.49%
Non-Metals · KOSDAQ-2.23%
Sector Evidence
46 KRX industry indexes (KOSPI 24 · KOSDAQ 22) · 15 up · 1 unchanged · 30 down The overall No. 1 was KOSDAQ Telecom +3.42%, but it is a small nine-stock index and is not treated as the day's main strength axis KOSPI Electrical & Electronics +0.20% · 19 advancers and 59 decliners among 84 constituents · the two largest market-cap names did most of the work in lifting the index 39 official KRX theme indexes · 18 up · 21 down · a separate family from industry indexes KOSDAQ Top 10 Index -3.04% · all 10 constituents down · KOSDAQ Top 15 Index -2.71% · all 15 constituents down K-AI Secondary Battery -3.19% · K-AI Defense TOP5+ -2.98%, all 10 constituents down · AI Power Infrastructure -2.13%, only 1 of 15 constituents up Advancer ratio · KOSPI 49.3% (450/912) · KOSDAQ 39.6% (689/1,738) · numerator is advancers plus limit-up stocks; denominator includes unchanged stocks KOSPI detail · 4 limit-up · 446 up · 40 unchanged · 422 down · 0 limit-down / KOSDAQ · 3 limit-up · 686 up · 98 unchanged · 950 down · 1 limit-down Sector returns are market-cap-weighted index changes, not measures of net money inflow by sector
CHANGE / 05
The Answer to Yesterday's Questions
Today's results against yesterday's confirmation criteria
YESTERDAY → TODAY
Two of yesterday's three questions were answered by today's data · Other Corporations and related opposite-side buying did not shrink, and August semiconductor exports reached an all-time highThe remaining question - the index sign versus the share of advancing stocks - stayed divergent for a fourth straight session since Aug. 27The structure in which the index rebound depends on treasury-share demand remained in place for a second day
01
Samsung Electronics + SK hynix opposite-side buying
KRW 1.5454tn
→
KRW 1.5914tn
02
Monthly semiconductor export high
$44.8bn · Jun.
→
$46.65bn · +209%
03
KOSPI
40.2%
→
49.3%
CATALYST / 06
SK On's First Major U.S. ESS Volume
The single event that received an observable price reaction today
SK INNOVATION · SEP. 1 CLOSE
KRW 135,300+KRW 9,800 · +7.81%
Subsidiary SK On Signs LFP Battery Cell Supply Contract for ESS with U.S. NeoVolta Power
WHAT · CONTRACT
SK On and U.S. ESS company NeoVolta Power · supply of LFP pouch battery cells for energy-storage systemsSigned Aug. 27 and disclosed Aug. 31Cells to be produced at SK On's Georgia plant in the United States
TERMS · CONTRACT
9GWh over five years beginning in 2027The companies plan to pursue a separate contract for another 9GWh within the year · total cooperation could reach 18GWh if that additional deal is completedContract value was not disclosed · roughly KRW 1.5tn is an industry and securities-market estimate
MEANING · INTERPRETATION
SK On secured 9GWh against its 20GWh ESS order target for this year · 45% of the targetIts first major deal broadening the product and customer mix from high-nickel EV batteries into for The contract also connects directly to utilization of the company's U.S. manufacturing base
MARKET · REACTION
Fourth consecutive gainForeign +KRW 36.6bn · institution +KRW 36.1bn net buying / individual -KRW 71.1bn net sellingKOSPI Chemicals was -0.16%, so the move was not a sector-wide rally
NEXT / 07
What to Check Next
Conditions that can actually be scored, not probabilities
Does opposite-side buying in Samsung Electronics and SK hynix stay above KRW 1tn?
This tests whether the index remains dependent on treasury-share demand for a third day · score the next session's Other Corporations net buying together with the KOSPI direction
Does the KOSPI advancer ratio move above 50%?
The ratio has diverged from the index sign for four straight sessions since Aug. 27 · if the 50% line and the KOSPI direction point the same way, breadth has reconnected with the index
After ISM and JOLTS, do the U.S. 10-year yield and September hike probability move higher again?
This tests whether the forces behind today's opening decline persist · score against the U.S. 10-year yield at 4.758% and the CME FedWatch probability of a September hike
Only the index was defended · neither trading activity nor risk appetite returned.
Sources · Data Basis
As of Sep. 1, 2026 · finalized KOSPI and KOSDAQ close Index open/high/low/close · market breadth · turnover · aggregate investor flows (individual, foreign, institution) · program trading · basis · short selling: Korea Exchange finalized close data and Naver Finance Intraday path: Naver Finance KOSPI intraday chart Stock-level investor flows: Korea Exchange closing investor trading data · collected Sep. 1 Other Corporations aggregate net buying and consecutive-day count: closing market-commentary aggregation Industries: 46 KRX Index industry indexes (KOSPI 24 · KOSDAQ 22) · Sep. 1 close Themes: 39 official KRX theme indexes · Sep. 1 close · separate family from industry indexes August preliminary exports and imports: Ministry of Trade, Industry and Energy · Korea Customs Service · released Sep. 1 at 09:00 Overseas indexes, rates and commodities: Aug. 31 U.S. close · Yahoo Finance and Naver Finance U.S.-Iran military clashes and international oil prices: press reports · Korean refiner returns based on the Sep. 1 domestic close September hike probability: CME FedWatch · as of Aug. 31 SK On-NeoVolta Power supply contract: company announcement and press reports · 9GWh is the confirmed contract; another 9GWh remains under pursuit · contract value is undisclosed and roughly KRW 1.5tn is an industry/securities-market estimate · the share of SK On's ESS order target is based on the stated volume SK Innovation close KRW 135,300 · Maeil Business Newspaper market quote and closing coverage
