Part 7 · Connecting the economy to stocks · Lesson 39
Reading investor sentiment: VIX and margin loan balance
Behind market numbers are people's feelings. Measure fear with the VIX and greed with the margin loan balance.
QToday's question
A day when everyone is terrified, or a day when everyone is borrowing money to buy: which one is riskier?
On March 16, 2020, the US fear index, the VIX, closed at 82.69, a record. Looking back, that was close to the bottom for stock prices (Lesson 34). Conversely, the times when money borrowed to invest swelled to record highs were times when everyone was optimistic. In this lesson, we read two thermometers that measure the market's mind.
MAPLearning map for this lesson
We build it up in three steps. At the end of each step, a 'Quick check' lets you test your understanding before moving on.
In Lesson 1 you learned that the multiple (P/E) expands and shrinks with investor sentiment, and in Lesson 24 that money flows into the dollar during risk-off periods. Also recall the foreign investor flows in Lesson 27 and August 5, 2024 in Lesson 32. Today you learn how to measure that 'sentiment' with numbers.
- STEP 1 · Basic conceptsThe VIX, which measures fear
You can explain what the measures and roughly what mood 20, 30 and 40 represent.
- STEP 2 · Understanding the mechanicsThe margin loan balance, which measures greed
You can explain why the grows, and how deepens declines.
- STEP 3 · Real-world applicationReading both thermometers together
Looking at the VIX, the margin loan balance and foreign investor flows together, you can judge whether the market is leaning toward fear or overheating, and decide what to check on your own side.
STEP 1The VIX, which measures fear
A stock price is a number, but it is people who move that number. Let's start with the main figure that measures how scared people are.
Easy analogy · The price of an umbrella
When a rumor spreads that it might rain tomorrow, umbrellas get more expensive. It hasn't rained yet, but worry alone that 'it might rain' pushes the price up. The VIX is the umbrella price of the stock market. The more investors pay for insurance against declines (options), the higher the VIX goes.
The is an index the Chicago Board Options Exchange calculates from S&P 500 option prices. It expresses, as an annualized percentage, how much the market expects to swing over the next 30 days. A VIX of 20 roughly means the market expects a swing of about 20% up or down over a year. That is why it is nicknamed the fear index. Because demand for insurance rushes in when stock prices fall, the VIX usually moves opposite to stock prices.
Getting a feel for the numbers makes the news easier to follow. From 1990 to September 2026, the median VIX close is about 17.6 and the average is about 19.4.
These zone boundaries are a rule of thumb Robin Invest set to aid understanding; they are not official thresholds.
Yearly VIX high (bars) and yearly average (dots), 2005 – Sep 2026
Tap a bar to see the day of greatest fear that year.
Source: FRED VIXCLS (CBOE VIX daily close), 2005-01-03 – 2026-10-01. Yearly highs and averages calculated by Robin Invest. Intraday highs can be higher than closes. Checked 2026-10-05.
Every year with a tall bar had a shock worth remembering. Prominent examples are the 2008 financial crisis (80.86 on Nov 20), the 2020 COVID shock (82.69 on Mar 16, a record) and the 2025 tariff shock (52.33 on Apr 8). On August 5, 2024, it closed at 38.57, and that day the KOSPI fell 8.77% (Lessons 21 and 32). Conversely, in 2017 the yearly average was only 11.1, and on Nov 3 it fell as low as 9.14. A period with too little fear is also read as a signal that 'everyone feels safe'.
Quick checkToday the VIX jumped from 18 to 34. How should you read the market mood?
STEP 2The margin loan balance, which measures greed
If the VIX is the thermometer of fear, the number most often watched as the thermometer of greed in the Korean market is the margin loan balance.
means borrowing money from a brokerage to buy stocks, often called 'debt-fueled investing' (beet-tu). The total of the amounts not yet repaid is the margin loan balance, which the Korea Financial Investment Association (KOFIA) publishes daily (with a one-day lag). The more prices rise and the stronger the expectation that 'it will rise more', the more people borrow to buy, and the balance swells.
The record shows the balance swelling sharply near the end of bull markets. KRW 25.65 trillion on September 13, 2021, during the 'Donghak ant' (retail investor) frenzy, stood as the record for a long time. The balance, which was around KRW 15 trillion in early 2025, grew to KRW 25.53 trillion by the end of October alongside the KOSPI rally. In 2026 it swelled to KRW 38.63 trillion on June 24, then fell by about KRW 11 trillion in a little over a month to KRW 27.40 trillion on August 4.
Margin loan balance (KOSPI + KOSDAQ), Apr 2026 – latest
Tap the line to see that day's balance.
Source: KOFIA FreeSIS 'Credit Balance Trend', daily balances of margin lending (KOSPI and KOSDAQ). Values loaded from Robin Invest Market Data (Short Selling & Margin Loans).
How forced liquidation amplifies declines
Stocks bought with borrowed money are held as collateral. When prices fall and the collateral value drops below a certain ratio (usually around 140%, varying by brokerage), the brokerage demands additional collateral, and if it isn't supplied, the shares are sold by force. This is . Because forced selling comes out regardless of price, it pushes prices down further, and that decline triggers more forced liquidation. That is why, in a market with a lot of accumulated debt, declines speed up like a 'slide' rather than a 'staircase'. You can check in advance at what price your own margin account would be hit by forced liquidation with the Margin Call (Forced Liquidation) Price Calculator.
Common misconceptions
- "When the VIX is high, it's always time to buy?"
- Moments of peak fear have often been near the bottom, but in 2008 stock prices kept falling for several more months even after the VIX went above 40. The VIX tells you that 'swings are large'; it is not a signal that marks the 'bottom'.
- "If the margin loan balance is at a record high, a crash is coming soon?"
- The balance naturally grows as the market gets bigger. What matters more than the record itself is the speed of increase and whether the balance holds up when prices turn down. A market with a large balance is read as one where 'declines can easily snowball once they start'.
- "The VIX is a US indicator, so it has nothing to do with Korea?"
- As seen in Lesson 32, fear in the US market easily spreads to the KOSPI the next day. During risk-off periods, foreign selling and a weak won sometimes pile on together (Lessons 24 and 27).
Quick checkIn a market where the margin loan balance is at a record high, prices fell 5% in one day. What should you watch out for over the next few days?
STEP 3Reading both thermometers together
One thermometer alone is easy to misread. Looking at fear, debt and the direction of foreign money together makes the market's mind much clearer.
Sentiment thermometer · Gauging fear and overheating with three numbers
This is a simplified educational model. It scores the three numbers with set weights and is not a real market forecast. For the 'End of Sep 2026' scene, the VIX is the FRED VIXCLS close on 2026-09-30 (16.34); the margin loan balance change is KOFIA's 2026-08-31 (KRW 33.25 trillion) → 2026-09-30 (KRW 33.39 trillion), about +0.4%, rounded to 0%; and foreign investor flows are set to neutral as an example.
We read the three numbers together because each measures something different. The VIX is 'how scared are people right now', the margin loan balance is 'how much debt have people taken on to be in the market', and foreign investor is 'is big money coming in or going out'. The signal gets stronger when all three point the same way. For example, a market with a low VIX, a fast-growing margin loan balance and foreign investors selling is closer to overheating driven only by individuals' debt. Conversely, if the VIX spikes, the margin loan balance drops sharply and foreign investors are selling, fear is at its peak.
A saying often heard in investing is 'be greedy when others are fearful', the idea of . But this saying is only useful for people who have a plan set in advance and spare funds. It is safer to use sentiment indicators not as signals for when to buy or sell, but as a mirror to check whether you are being swept up in the crowd.
For stocks, it goes like this
| The market's mood | What it often looks like | What to check on your side |
|---|---|---|
| Fear (VIX above 30) | Growth stocks and high-volatility sectors swing sharply, while defensive stocks hold up relatively well (Lesson 22) | Whether you use margin, your forced-liquidation price, your pre-set plan for scaling in |
| Overheating (margin loan balance surging) | Money piles into themes and small caps, and daily swings get larger | Whether your position size has grown beyond your target, the share of debt |
| Heavy foreign selling | A weak won and weakness in large caps tend to coincide (Lesson 27) | The exchange rate and sectors with a large foreign ownership share, such as semiconductors |
You can check the daily margin loan balance and short-selling flows in Short Selling & Margin Loans under Market Data, and foreign investor flows in Investor Flows.
It isn't always so. Fear can deepen, and overheating can last a long time. Sentiment indicators are reference material that show the 'degree of crowding' rather than direction. This is not a recommendation to buy or sell any specific stock or product.
Quick checkThe VIX is low at 13, but the margin loan balance grew 20% in a month and foreign investors keep selling. Which side is it closer to?
✓What we learned today
- The VIX is the 'swing expected over the next 30 days', calculated from S&P 500 option prices. The median since 1990 is about 17.6; above 30 is read as anxiety and above 40 as a fear phase.
- The VIX's record closes are 82.69 on March 16, 2020 and 80.86 on November 20, 2008. Moments of peak fear were often close to the stock-price bottom, but they are not a signal that marks the bottom.
- The margin loan balance is the size of stocks bought with borrowed money. It tends to swell near the end of bull markets, such as KRW 25.65 trillion on September 13, 2021 and KRW 38.63 trillion on June 24, 2026.
- In a market with a lot of debt, when prices fall the collateral becomes insufficient and forced liquidation comes out, which can deepen the decline.
- Sentiment indicators are not tools for calling direction; they are tools for checking 'whether the market is crowded to one side right now'. When it is crowded, first check your own debt and position size.
Now all the tools are gathered: economic indicators, interest rates, exchange rates and even sentiment. In the next lesson, you practice breaking down real economic news headlines line by line into cause → reaction → impact.
Quiz5-question quiz
Pick an answer and it's graded right away with an explanation.
Q1. What is the VIX (fear index) calculated from?
The VIX is the swing expected over the next 30 days, calculated from S&P 500 option prices. It rises as demand for downside insurance (options) piles up.
Q2. On which day did the VIX record close (82.69) occur?
It was March 16, 2020, during the COVID shock. November 20, 2008 was 80.86, April 8, 2025 was 52.33, and August 5, 2024 was 38.57.
Q3. What does a fast-growing margin loan balance mainly signal?
The margin loan balance is the size of stocks bought with borrowed money. It tends to grow as expectations of further gains rise.
Q4. Why can a price decline speed up in a market with a lot of accumulated debt?
When the collateral ratio falls below the threshold, the brokerage sells the shares by force. Selling regardless of price can trigger further declines.
Q5. What is the most appropriate way to use sentiment indicators?
Sentiment indicators are not signals that call bottoms or tops. Use them as a mirror: look at the degree of crowding and review your plan and risk management.
NextTerms · Next lesson · Related tools
The expected volatility over the next 30 days, calculated from S&P 500 option prices. It rises as investors become more anxious.
Investor sentimentInvestor sentimentWhether investors are optimistic or pessimistic. With the same earnings, better sentiment gives a higher multiple.
Margin loan balanceMargin loan balanceThe total of the amounts not yet repaid on stocks that investors bought with money borrowed from brokerages. It is commonly viewed as the size of 'debt-fueled investing', and KOFIA publishes it with a one-day lag.
Forced liquidationForced liquidation (margin call)When the collateral value of stocks bought on margin or with unsettled-payment trades (misu) falls below the threshold and additional collateral can't be supplied, the brokerage sells the shares by force. Because it is selling regardless of price, it can deepen declines.
Fear and greedFear and greedWhere market participants' sentiment sits between excessive pessimism (fear) and excessive optimism (greed). It is gauged with indicators such as the VIX, the margin loan balance and investor flows.
Contrarian investingContrarian investingAn investment attitude of considering the opposite direction when the majority is crowded to one side. It is only meaningful when you have a plan set in advance and spare funds.
Risk aversion (safe-haven preference)Risk-offA phenomenon in which, when anxiety grows from events like war, financial crises, or sharp stock market drops, investors sell stocks and emerging-market currencies and flock to safe-haven assets such as the dollar, government bonds, and gold. The won generally weakens at such times.
Foreign investorForeign investorA collective term for overseas pension funds, asset managers, sovereign wealth funds, hedge funds, and others that register with the Financial Supervisory Service as foreign investors and trade Korean stocks. They calculate returns in their own currency, such as dollars, so they are sensitive to the exchange rate.
Net buying / net sellingNet buying / Net sellingThe amount bought minus the amount sold over a given period. Positive means net buying and negative means net selling. It is tallied daily by foreign investors, institutions, and individuals.
Priced inPriced inA state in which something expected to happen is already reflected in prices such as stock prices or interest rates. If things happen as expected, prices do not move much.
Put what you learned to use right away
Short Selling & Margin Loans→Margin call calculator→Investor flows→This is educational material and not investment solicitation. There is no guarantee that past relationships will repeat in the future.