6 trading days in a row of selling positions by foreigners turned to buying in both spot and futures markets, resulting in a relatively large increase which is quite pleasant. The FED interest rate hike significantly reduced uncertainty, and if oil prices continue to fall, there is upward potential. I just wish Trump wouldn't make any more trouble.

🇰🇷 Korea Stock Market Closing Briefing — September 18, 2026

Basis: After the close of regular spot market and KOSPI200 weekly futures & options on September 18, 2026

Today, HTS data provided by users after 3:45 PM was prioritized, and cross-checked with Korea Exchange quoted closing data released from 3:48 to 5:17 PM. KOSPI 6,894.23(+2.66%), KOSDAQ 827.12(+0.60%) are consistent across multiple closing data sources. Foreigners turned to net buying after seven consecutive trading days of net selling, and Samsung Electronics and SK Hynix led the index rise. Bridge Economy

Today's market in one sentence:

“Semiconductors led the index higher, foreigners returned to both spot and futures markets, price increases were accompanied by a rise in open interest (OI), making it one of the highest quality risk-on rebounds in September. However, program arbitrage selling and high volatility still require caution.”

① Today's Market at a Glance

② Today's Market Quant Score

76 / 100 — Strong Risk Appetite + Trend Recovery

A significant improvement from yesterday's 58 points → today's 76 points.

61 / 100

The decline in US long-term Treasury bond yields and international oil prices improved risk asset sentiment, and the AI·semiconductor boom in the US stock market was linked to domestic large semiconductors. Bridge Economy

However, the fact that the won/dollar exchange rate is still in the 1,380 won range makes it difficult to fully evaluate the macroeconomic environment as a risk-on phase.

③ Foreigners·Institutions Real Trading

This is the final value of HTS user.

Public data aggregates foreigner KOSPI net buying at approximately 4,252 billion~9,773 billion won and institutions at approximately 1 trillion 5,056 billion~1 trillion 7,168 billion won. There is a difference in figures between HTS and the data, but the direction of **net buying by foreigners and institutions is completely consistent**. News Today

★ The Most Important Change Today

Foreigners switched to net buying today after selling consecutively until yesterday.

Initially, foreigners were selling, but they switched to buying in the morning and continued their buying momentum. Yonhap News

More importantly, it is not just simple index buying but **concentrated buying of semiconductors**.

④ KOSPI200 Futures + OI + Basis + Program

Investors by Futures

The most important number in the derivatives market today is:

Foreigner Gifts +1,292.6 Billion Won

is.

And the spot price:

+986.4 Billion Won

is.

Therefore, today is completely different from yesterday.

Foreigner Spot↑ + Futures↑ + K200↑

occurred a direction match>.

★ Outstanding Orders (OI)

Previous day:

131,559

Today:

132,567

Therefore:

+1,008 Contracts

is.

Futures prices also:

1,062.75 → 1,092.45

soared.

In other words, today's combination is:

Price↑ + OI↑ + Large-scale Foreigner Futures Buying

is.

This is a much better structure than yesterday's Price↑ + OI↓.

Position Character Probability

※ The Outstanding Orders (OI) is the total market OI, not the foreigner OI, so it cannot be definitively said that foreigners created 1,008 contracts as new Longs.

However, the combination of Price +2.79% + Foreigner Futures +1.29 trillion + Total OI +1,008 significantly increases the possibility of new Long inflows.

Intraday → Closing OI Change

Intraday HTS:

High 133,855

→ Sharp decline

→ Low 131,904

→ Afternoon rebound

→ Final 132,567

is.

In other words, a large liquidation of existing positions occurred in the early part of the session, but OI increased again afterwards.

This is important.

★ Morning = Liquidation Character

★ Afternoon = New Position Reconstruction Character

This is judged as a mixed structure.

Basis

K200:

1,090.23

Futures:

1,092.45

Therefore:

+2.22p

Normal Contango.

Although it has decreased from +4.48p the previous day, the futures premium has been maintained during the spot price surge.

Program Trading

User HTS Final:

Here is the only clear flaw in today's bullish market.

Index +2.66% but non-arbitrage programs are net selling

.

In other words, it is still difficult to say that passive overseas capital has completely returned.

⑤ Options Market

HTS amount based:

Foreigners bought +1.29 trillion in futures while also holding Puts at +1.2 billion.

Therefore:

Futures Long + Put Insurance

This pattern exists to some extent.

In other words, foreigners are participating in the rally while not completely eliminating downside tail risk.

Major Events

The HTS data on major events for the current month is limited, so detailed OI and PCR for each event will be:

Data Unconfirmed

.

The overall Put/Call Ratio (PCR) will not be arbitrarily calculated either.

⑥ Semiconductors and Key Leading Stocks

Today's market leader is once again semiconductors.

Samsung Electronics

261,000 won +3.37%

SK Hynix

1,857,000 won +6.42%

.

Samsung Electronics' regular trading closing price of 261,000 won is also confirmed in separate market data. AlphaSquare

Public disclosure data also showed that the strength of the two stocks was at the heart of today's KOSPI rise.

Especially HTS industry:

Electronics +4.46%

It is overwhelming in the entire market.

The government's policy of designating Cheonan·Asan semiconductor post-processing, Gunsan·Iksan semiconductor chemical materials, etc. as specialized industrial complexes for materials, parts, and equipment is also positive in the medium term.

⑦ 12 Fixed Sectors Quant

8 ★ Top 15 Sectors for Today & Key Stock Signals

★ Yesterday the leadership was centered on shipbuilding and defense, but today the primary leadership has shifted to semiconductors and AI infrastructure.

The government's new specialized zones for materials, parts, and equipment simultaneously include shipbuilding, defense, and semiconductors, so these three pillars have higher policy continuity than a simple one-day theme. Yonhapnews

⑨ KOSPI / KOSPI200 Technical Structure

KOSPI:

6,885.70 Opening Price

→ 6,830.95 Intraday Low

→ 6,914.08 High

→ 6,894.23 Closing Price

. News Today

What is very important is that after a gap-up, it maintained most of the gap.

It is the complete opposite of yesterday.

Yesterday

Gap-up → Gave back gains

Today

Gap-up → Correction → Rally → Closed near highs

Therefore, the technical quality is much better.

⑩ Elliott/Neely + Wyckoff + Volume Profile

Today's K200 Futures Volume Concentration:

Therefore, today's key Value Area is:

1,084~1,093

.

The closing price of 1,092.45 is at the top of the value area.

This is a strong close in the short term.

🟢 Scenario A — Resumption of Uptrend

50% — Base Scenario

Conditions:

1,088~1,090 Support

• Continued concurrent buying by foreigners in spot and futures

• OI Maintained/Increased

Target:

1,095 → 1,105 → 1,115

Invalidation:

1,083 foreigners selling + conversion to gift

🟡 Scenario B — Rise followed by period adjustment

32%

1,095 resistance

→ 1,083~1,095 box

→ Circulation trading from semiconductors to shipbuilding·defense·robots

This scenario is a healthy adjustment.

Invalidation:

1,100 breakthrough with volume

🔴 Scenario C — Rebound failure

18%

Conditions:

1,083 downward deviation

• Foreigners' real stock selling conversion again

• Price↓ + OI↑

Target:

1,075 → 1,065 → 1,056

Wyckoff

Currently, the structure is:

Re-accumulation → Sign of Strength candidate

for an upward evaluation.

However, the confirmation condition is breaking through 1,095~1,100 and holding 1,088 after pressure.

⑫ Key support and resistance for the next trading day

The most important number for the next trading day

1,088

.

Above 1,088, we prioritize the possibility of extending today's rise.

⑫ Risks to be most wary of

First, today's surge was very large, so gap-up chasing buying on Monday has a higher risk compared to expected returns.

Second, program arbitrage trading is about -2,308 billion won net selling. Although the direction of foreign real and futures has improved significantly, there is still insufficient evidence that passive funds have completely converted.

Third, VKOSPI 43.56. The index rose 2.66%, but the volatility index actually increased by +1.26%. This means that the options market has not yet fully priced in tail risks.

Fourth, the won/dollar is still in the 1,380 won range.

Therefore, you should not confirm “Adjustment Completion” today based on just one day's view.

⑬ Final Market Dashboard

⑭ Today's Key Conclusion

Today is the day when the structure of the derivatives market has changed most importantly among recent days.

The key combination is:

KOSPI +2.66%

• KOSPI200 +3.02%

• Foreigners Net Buying +9,864 billion won

• Foreigners Futures Net Buying +1.2926 trillion won

• OI +1,008

• Futures +2.79%

.

This is not simply explained by a **short covering (Short Covering)**.

Yesterday, it was **price↑ + OI↓**, so the possibility of short covering was high, but today it changed to **price↑ + OI↑**.

Therefore, from today onwards:

Short Covering → Long Build (New Buying Positions)

The possibility of opening in earnest should be considered.

Especially, the fact that foreigners **bought both spot and futures** is important.

Another decisive change is the leading industry.

Yesterday:

Shipbuilding → Defense → Machinery

Today:

Semiconductors·AI → Electricity·AI Infrastructure → Shipbuilding·Defense

This is a **multiple leading sector structure**.

Samsung Electronics +3.37%, SK Hynix +6.42% represent this, and the public closing data also confirms that semiconductors were the core driving force of KOSPI's rise today. Bridge Economy

However, it is still one step away from aggressively increasing the weight to the entire market.

The confirmation condition for that is:

**① K200 Futures 1,088 Defense**

② Attempt to break through 1,095~1,100
③ Continuation of Foreigners' Net Spot Buying
④ Continuation of Foreigners' Net Futures Buying
⑤ Maintaining Price↑ + OI↑
⑥ Program Neutral Buying Conversion**

.

If **four or more of these are confirmed simultaneously**, the market quant score can be raised to 80 points or higher, and the possibility of a new upward wave proceeding after the short-term adjustment is significantly increased.

On the other hand, if **1,083 breach + Foreigners' simultaneous selling of spot and futures + OI increase** appears, today's rise should be re-evaluated as a **strong technical rebound rather than the start of a new upward wave**.

★ The **key to Monday's strategy is not chasing buying**. Rather than following today's +2.66% increase, it is better to **prioritize the pressure points of semiconductors·AI, power equipment, shipbuilding·defense, and confirm the support level of K200 Futures 1,088~1,083 before increasing risk exposure**.