Episode 3. Why Do Stock Prices Go Up and Down? The Forces That Move Prices Before We Begin: One Clear Definition
Episode 3. Why Do Stock Prices Go Up and Down?
The Forces That Move Prices
Before We Begin: One Clear Definition
A stock price is not the value of a company itself, but the price the market agrees on at a specific moment.
Because prices are based on collective opinions, expectations, and emotions,
they fluctuate constantly—and often appear disconnected from reality.
In Episode 1, we defined stocks as ownership.
In Episode 2, we explained the stock market as a system for capital and growth.
In this episode, we answer a question every beginner asks:
Why does the price of that ownership move so much?
Understanding this turns frustration into structure.
Recommended Keywords
stock price movement,why stock prices change,stock market basics,price vs value,investment psychology,supply and demand,company valuation,long term investing
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*This article is for general informational purposes only and does not constitute investment advice. All investment decisions are the reader’s responsibility. |
1) Price Is Not Value
Many beginners assume:
“A good company should have a stable stock price.”
“If the price drops, the company must be failing.”
But markets don’t work that way.
Value: the company’s long-term ability to generate profits and cash flow
Price: the number buyers and sellers agree on right now
A stock price is closer to a poll of opinions than a measurement of truth.
That’s why:
strong companies can fall
weak companies can rise
Confusing price with value is one of the biggest early mistakes.
2) The Only Immediate Rule: Supply and Demand
No matter how complex markets look, price changes follow one simple rule:
When demand exceeds supply, prices rise.
When supply exceeds demand, prices fall.
Everything else—news, earnings, interest rates, emotions—
exists only because it influences supply and demand.
Understanding this simplifies market behavior dramatically.
3) Four Core Forces That Move Stock Prices
① Company Performance (The Foundation)
Over the long term, stock prices tend to reflect business performance.
Key questions include:
Is revenue growing?
Are profits sustainable?
Is cash flow healthy?
Strong fundamentals often create a price floor over time.
But there is a catch:
performance reflects the past.
Markets are forward-looking.
② Future Expectations (Pricing the Unknown)
Stock prices often move based on what has not happened yet.
Investors constantly ask:
“Will this company still perform well three years from now?”
This is why:
prices can rise before earnings improve
prices can fall even when results look strong
Markets price:
industry shifts
technology adoption
policy changes
competitive advantages
Expectation often moves prices faster than reality.
③ The Money Environment (Interest Rates & Liquidity)
Stock prices are affected by the price of money itself.
Low interest rates → future profits look more valuable
High interest rates → present cash becomes more attractive
This explains why:
growth stocks are highly rate-sensitive
defensive stocks fluctuate less
Sometimes prices move not because companies changed,
but because financial conditions did.
④ Investor Psychology (The Fastest Force)
In the short term, emotion dominates.
Fear: “It will fall even more.”
Greed: “If I don’t buy now, I’ll miss it.”
Emotion spreads quickly.
Fear accelerates declines.
Greed amplifies rallies.
This is why prices often:
overshoot on the upside
collapse too far on the downside
Most individual investors lose discipline here.
4) Why Prices Fall After “Good News”
Strong earnings, but the stock drops
Positive headlines, yet prices fall
Common reasons:
Expectations were already too high
Future outlook weakened despite good results
Overall market conditions deteriorated
News is not a verdict.
It’s a trigger, not a conclusion.
5) Why Stock Prices Overreact
Markets are driven by people, not machines.
Psychological patterns include:
loss aversion
herd behavior
confirmation bias
These forces push prices away from intrinsic value.
However:
Extreme moves often create future corrections.
This is why long-term investors watch emotional extremes closely.
6) Common Misconceptions Beginners Hold
These thoughts are widespread—and dangerous:
“The price fell, so the company is broken.”
“The price rose, so it’s safe.”
“Charts predict the future.”
Prices are outcomes, not causes.
The real drivers are:
businesses
financial conditions
human behavior
7) A Healthy Framework for Watching Prices
Beginners benefit from simple rules:
Treat short-term moves as noise
Treat business changes as signals
Record reasons, not just prices
This reduces overtrading and emotional stress.
8) Five Practical Questions to Ask
When prices move sharply, ask:
What triggered this move?
Did the business itself change?
Is this market-wide or company-specific?
Am I reacting emotionally?
Is my position size reasonable?
9) Key Takeaways (7 Lines)
Stock prices are market prices, not intrinsic value.
Supply and demand determine immediate movement.
Business performance shapes long-term direction.
Expectations pull prices forward.
Interest rates shape valuation context.
Psychology dominates short-term moves.
Clear standards reduce emotional decisions.
*This article is for general informational purposes only and does not constitute investment advice. All investment decisions are the reader’s responsibility.
Sources
Korea Exchange (KRX)
Bank of Korea
Financial Supervisory Service
CFA Institute
Closing
Prices change constantly, but the reasons behind them repeat.
In the next episode, we explore the starting point of all stocks: Public vs Private Companies.
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