Support and Resistance, Why They Form and How to Calculate Them

TL;DR

• Support is a price zone where declines repeatedly stop, resistance is a zone where rises repeatedly stop.
• Formation factors include buyer and seller psychology, concentrated past trading volume, and participants remembering price levels.

Definition: What are support and resistance

Support is a price zone where a falling price has stopped and bounced several times. Conversely, resistance is a zone where a rising price has stopped and reversed several times. Drawing a line on a chart is a convenience, and it is more accurate to think of these as zones rather than a single point.

Why they matter

First, they reveal trading psychology and order concentration. When many investors buy or sell at the same price zone, an imbalance in supply and demand occurs there. Second, they serve as risk management reference points. Traders refer to price zones that previously reacted when setting stop losses or profit targets. Third, they can be interpreted as trend reversal signals. Repeated breaks of a support zone indicate stronger downward pressure.

How they form: what actually works

• Psychological anchors: People remember levels where price previously paused, and tend to buy or sell again at those levels.
• Concentration of order volume: Large orders from institutions or algorithms at specific price levels can halt or reverse price moves in that zone.
• Technical and fundamental events: Dividends, earnings, policy changes and similar events can concentrate reactions at certain price levels.

Calculation example with hypothetical numbers

Suppose a stock shows four recent lows at 9,800원, 9,700원, 9,750원, and 9,820원. To mark a single support level, you can average them or use the median.

• Average method: (9,800 + 9,700 + 9,750 + 9,820) / 4 = 9,767.5원
• Median method: sorted values are 9,700, 9,750, 9,800, 9,820 so the median is (9,750 + 9,800) / 2 = 9,775원

Conservatively, view the support zone as 9,750원 to 9,800원. If the current price is 10,200원, the decline to that support zone is roughly (10,200 - 9,775) / 10,200 ≈ 4.2%. Use this figure as a reference for risk management or stop loss placement.

Common misconceptions

• Support and resistance are not absolute boundaries: Prices can always move out of a zone, so a single line is not a definitive forecast and should be read with volume and patterns.
• No single calculation method is universally correct: Methods to calculate support (average, median, focusing on recent lows, etc.) vary, so interpret flexibly.
• Past price action does not guarantee future results: Past reactions are only a reference, and major market changes can invalidate existing support and resistance.

Support and resistance are basic charting tools that reflect collective market behavior. Use them together with volume, trend, and news for comprehensive judgment.

This article is for informational purposes and not an investment solicitation.