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Indicators

Bollinger Bands

Bollinger Bands

A volatility indicator developed by John Bollinger, consisting of a 20-day moving average with bands set at ±2 standard deviations. The bands widen and narrow automatically with volatility. A squeeze (narrow bands) signals an impending big move, while touches of the upper or lower band suggest overbought or oversold conditions, respectively.

Key Takeaways

Volume Indicator Analysis

Source: John J. Murphy, Technical Analysis of the Financial Markets — Volume Indicators Chapter


1. Volume Analysis

Volume is the essential indicator for confirming the reliability of price movements and serves as the foundation of all technical analysis. Following the principle that "Volume precedes price," changes in volume reflect market participants' sentiment before price changes occur. If price shows what is happening, volume shows how much conviction is behind it.

Unlike traditional markets, the cryptocurrency market operates 24/7, which means volume patterns can vary significantly across different time zones. Volume tends to concentrate during overlapping sessions — particularly when Asian, European, and U.S. trading hours intersect — so time-of-day characteristics should always be factored into volume analysis.

Fundamental Principles of Volume

  • Uptrend: Volume increases on price advances and decreases on corrections — this is normal
  • Downtrend: Volume increases on price declines and decreases on rallies — this is normal
  • Sideways market: Volume gradually decreases as buying and selling pressure reach equilibrium

The key principle is that volume should confirm the direction of the trend. In a healthy trend, volume expands on moves in the trend direction and contracts on moves against it.

Core Validation Rules

Healthy Trend Confirmation

  • Healthy uptrend: Price ↑ + Volume ↑, Price ↓ + Volume ↓ → Buying pressure overwhelms selling pressure
  • Healthy downtrend: Price ↓ + Volume ↑, Price ↑ + Volume ↓ → Selling pressure dominates
  • During pattern formation: Gradual volume decline is a normal process of supply-demand equilibrium. Declining volume inside triangles or wedges is interpreted as energy accumulation

Breakout Validation

  • Valid breakout: A break above resistance or below support should be accompanied by a volume increase of at least 150% above average. In cryptocurrency markets, using a 200% threshold is safer
  • Fakeout: A breakout without a volume surge has a high probability of being false. This is especially common in low-liquidity altcoins
  • Re-validation: If volume decreases during a pullback after a breakout, this is a positive signal reconfirming the breakout's validity
  • Upside vs. downside breakouts: Murphy emphasizes that volume confirmation is particularly critical for upside breakouts. Downside breakouts can proceed under their own weight (gravity) without volume confirmation

Warning Signals

  • Divergence: When price makes a new high but volume declines, this is a bearish divergence warning — it means fewer participants are buying
  • Trend weakening: Continuously declining volume on moves in the trend direction signals trend exhaustion
  • Climax: A sharp volume spike followed by rapid decline is a short-term reversal signal. A selling climax suggests potential bottom formation after panic selling, while a buying climax suggests potential top formation after euphoric buying

Practical Application Guidelines

Volume Level Classification

ClassificationCriteria (vs. 20-day Average)Interpretation
Low volumeBelow 50%Low market interest, sideways likely
Normal volume50–150%Standard level, trend maintenance
High volume150–300%Major event occurring, potential breakout signal
Surge volumeAbove 300%Climax or decisive turning point

Situational Interpretation

  • Pattern completion: Confirm a volume surge when triangles, flags, and other patterns complete their breakout. A breakout without volume may be a trap
  • Gap occurrence: A gap accompanied by volume is a bullish continuation signal; a gap without volume is likely to be filled
  • New highs/lows: New highs or lows formed without supporting volume carry a high risk of reversal

Cryptocurrency Market-Specific Considerations

  • Beware of wash trading: Volume may be artificially inflated on certain exchanges, so always use data from reputable exchanges
  • Stablecoin inflows/outflows: The flow of stablecoins into exchanges is a useful metric that complements traditional volume analysis
  • Combine with on-chain data: Cross-referencing actual blockchain transaction volume with exchange trading volume significantly improves analytical accuracy

2. OBV (On-Balance Volume)

OBV (On-Balance Volume) is a cumulative volume indicator first introduced by Joe Granville in his 1963 book Granville's New Key to Stock Market Profits. By adding or subtracting each day's volume based on price direction, OBV tracks the flow of funds — the direction of smart money.

The core premise of OBV is simple: volume precedes price. When large institutions or informed investors (smart money) begin accumulating, volume increases before price changes, and this is reflected in OBV. The absolute value of OBV is not important — what matters is the direction (trend) of OBV.

OBV Calculation

  • Up day (close > previous close): Previous OBV + today's volume
  • Down day (close < previous close): Previous OBV − today's volume
  • Unchanged day (close = previous close): Previous OBV carries forward

For example, if Bitcoin closed higher than the previous day with a daily volume of 10,000 BTC, then 10,000 is added to OBV. OBV uses a simple yet effective logic: "attribute the entire day's volume to the winner (buyers or sellers)."

Core Validation Rules

Trend Confirmation Signals

SituationOBV PatternPrice PatternInterpretationReliability
Bullish confirmationOBV risingPrice risingUptrend likely to continueHigh
Bearish confirmationOBV fallingPrice fallingDowntrend likely to continueHigh
Bullish divergenceOBV risingPrice falling/flatAccumulation underway, upward reversal imminentMedium
Bearish divergenceOBV fallingPrice rising/flatDistribution underway, downward reversal imminentMedium

Divergence Validation Rules

  • Bearish divergence: When price makes a new high but OBV fails to surpass its previous peak and declines, this warns that smart money has already begun distributing (selling)
  • Bullish divergence: When price makes a new low but OBV holds above its previous trough, this signals that quiet accumulation (buying) is taking place at lower prices
  • Confirmation window: A price reversal should appear within 3–5 trading days after the divergence occurs for it to be considered valid. If the divergence persists for an extended period, the trend may last longer than expected — exercise caution
  • Multiple divergences: Two or more consecutive divergences significantly increase reliability

Advanced Analysis Techniques

OBV Trendline Analysis

Murphy emphasizes that traditional chart analysis techniques can be applied directly to OBV itself. This is the key characteristic that elevates OBV beyond a simple secondary indicator.

  • Rising trendline: A line connecting successive OBV lows. As long as this line holds, fund inflows are healthy
  • Falling trendline: A line connecting successive OBV highs. Below this line, fund outflows persist
  • Trendline break: An OBV trendline breakout is an early warning signal of a price trend reversal. It often occurs before the corresponding price chart trendline break

OBV Pattern Analysis

  • OBV triangle: Triangles may complete on the OBV chart before the price chart, providing advance directional clues
  • OBV double top/bottom: These form ahead of price double tops/bottoms, serving as advance confirmation of reversal patterns
  • OBV flag: Flag patterns appearing on OBV after sharp rallies or declines can forecast trend re-acceleration

Practical Trading Strategies

Timing Entries and Exits

  • Buy signal: When OBV breaks to a new high while price approaches resistance → watch for OBV to break out first with price following
  • Sell signal: When OBV breaks to a new low while price approaches support → prepare for potential support collapse
  • Standby zone: When OBV moves sideways without a clear direction, consider staying on the sidelines

Combining with Other Indicators

  • OBV + RSI: When both OBV and RSI show divergence simultaneously, reversal reliability increases substantially
  • OBV + Moving Average: Apply a 20-day moving average to OBV. When OBV is above its own moving average, fund inflows dominate; when below, fund outflows dominate
  • OBV + Bollinger Bands: If price touches the lower Bollinger Band while OBV is in an uptrend, this can be interpreted as a strong buying opportunity

Limitations of OBV

  • OBV assigns the entire day's volume to either buyers or sellers. Even on a day with massive intraday swings that closes only slightly higher, the full volume is attributed to buying pressure. This oversimplification can introduce noise
  • In cryptocurrency markets, extreme volume spikes (e.g., major events, new exchange listings) can distort OBV, so outliers should be accounted for in interpretation

3. Moving Averages

Moving averages smooth price data over a specified period to identify the direction and strength of a trend. They are the most fundamental trend-following tool in technical analysis. While simple, they form the foundation for all other technical analysis and can be combined with other indicators to build powerful trading systems.

Murphy clearly defines moving averages as "a following indicator, not a forecasting indicator." Moving averages generate signals only after a trend has already begun, so recognizing and working with this inherent lag is essential.

Types and Characteristics of Moving Averages

TypeCalculation MethodAdvantagesDisadvantages
Simple Moving Average (SMA)Arithmetic mean of closing prices over a set period; equal weight to all dataStable, less noiseSlow to react, influenced by old data
Exponential Moving Average (EMA)Exponentially greater weight assigned to recent pricesFast response, reflects recent price actionSensitive to noise
Weighted Moving Average (WMA)Linearly increasing weight assigned to more recent dataIntermediate characteristics between SMA and EMAComplex calculation, less commonly used

Practical tip: Due to the high volatility of cryptocurrency markets, many traders prefer EMAs. However, the 200-day SMA remains the most widely used benchmark for confirming long-term trends.

Core Validation Rules

Period-Based Classification and Usage

  • Short-term (5–13 days): Used for capturing short-term trading signals. Sensitive but prone to noise (false signals), so always use with confirmation indicators
  • Medium-term (20–50 days): Used for confirming intermediate trends; offers the highest practical utility. The 20-day line also serves as the centerline for Bollinger Bands
  • Long-term (100–200 days): The barometer of the primary trend. The 200-day line is the most closely watched by institutional investors and acts as a powerful psychological support/resistance level. When Bitcoin is above the 200-day line, the long-term outlook is generally considered bullish; below it, bearish

Crossover Signal System

Crossover TypeBuy SignalSell SignalCharacteristics
Price–MA crossoverPrice crosses above MAPrice crosses below MAMost basic signal
Dual crossover (Golden/Death Cross)Short-term MA crosses above long-term MAShort-term MA crosses below long-term MAMost widely used
Triple crossover4-day > 9-day > 18-day alignment18-day > 9-day > 4-day alignmentStrong trend confirmation signal
  • Golden Cross: The 50-day MA crosses above the 200-day MA — the classic signal heralding the start of a long-term uptrend
  • Death Cross: The 50-day MA crosses below the 200-day MA — a warning of a long-term downtrend reversal
  • Caution: Golden Crosses and Death Crosses are lagging signals, so by the time they occur, price has often already moved significantly

The 4-9-18 System in Detail

This is the triple crossover system introduced by Murphy, which confirms trade timing in stages.

  • Stage 1 (Warning): The 4-day MA crosses above the 9-day MA → Buy alert. It is still too early to enter
  • Stage 2 (Confirmation): The 9-day MA crosses above the 18-day MA → Buy confirmed. This is the proper entry point
  • Stage 3 (Completion): Full bullish alignment — 4-day > 9-day > 18-day → Strong uptrend established. Add to positions or hold

Sell signals follow the reverse sequence. The 4-day MA crossing below the 9-day MA is the warning; the 9-day MA crossing below the 18-day MA is the confirmation.

Advanced Analysis Techniques

Moving Averages as Dynamic Support and Resistance

Moving averages are not fixed horizontal lines — they serve as dynamic support and resistance levels that move with price.

  • Bull market: Moving averages act as dynamic support. Price frequently bounces off the 20-day and 50-day lines
  • Bear market: Moving averages act as dynamic resistance. Rally attempts are repeatedly rejected at moving average levels
  • Band effect: When multiple moving averages converge in a narrow zone, they form a powerful support/resistance band

Slope and Spacing Analysis

  • MA slope: Upward slope (uptrend), downward slope (downtrend), flat (sideways). A steeper slope indicates stronger trend momentum
  • MA spacing: Widening gaps between short-, medium-, and long-term MAs indicate trend acceleration; narrowing gaps indicate trend deceleration; convergence to a single point suggests an inflection point is imminent
  • Alignment: When all MAs are sequentially arranged below price (bullish alignment), a strong uptrend is in place. When arranged above price in reverse order (bearish alignment), a strong downtrend is in place. Tangled MAs indicate a directionless, choppy market

Practical Application and Limitations

Validity Conditions

  • Effective only in trending markets: Moving averages are inherently trend-following indicators and work well only when a clear trend exists
  • Sideways market limitations: In range-bound conditions, price crosses the moving average frequently, generating repeated whipsaw (false) signals. Minimizing losses during these periods is the key to running a moving average system successfully
  • Lag: This is the fundamental limitation of trend-following indicators — signals at turning points (tops and bottoms) arrive late. Shortening the period reduces lag but increases false signals, creating an inherent trade-off

Filtering Techniques (Reducing False Signals)

  • Volume confirmation: Verify whether a volume increase accompanies an MA breakout
  • Time filter: Confirm that the breakout holds for at least 2–3 days. If price reverses within one day, treat it as a false breakout
  • Percentage filter: Require price to penetrate the MA by a certain percentage (e.g., 1–3%) before recognizing it as a valid signal
  • Multiple confirmation: Verify that MAs across different periods are aligned in the same direction

Optimization by Market Environment

Market EnvironmentRecommended MA TypeRecommended Period Combination
High volatility (crypto surge/crash periods)EMAShort-term 5–20 day combinations
Stable trending marketSMA20–50 day combinations
Short-term scalping/day tradingEMA5, 13, 21 days
Medium-to-long-term swing/position tradingSMA or EMA20, 50, 200 days

4. Bollinger Bands

Bollinger Bands are a technical indicator developed by John Bollinger in the early 1980s. They consist of an upper and lower band set at standard deviation intervals around a 20-day moving average centerline. Bollinger Bands simultaneously measure relative price position and volatility, and their defining characteristic is that the bandwidth automatically adjusts to volatility — making them an adaptive indicator.

Statistically, approximately 95% of data falls within 2 standard deviations. Therefore, price moving outside the bands represents a statistically extreme condition. However, as Bollinger himself emphasized, touching a band is not, by itself, a buy or sell signal. The bands simply provide reference information about whether price is relatively high or low.

Bollinger Bands Components

  • Middle line (centerline): 20-day Simple Moving Average (SMA)
  • Upper band: Middle line + (2 × 20-day standard deviation)
  • Lower band: Middle line − (2 × 20-day standard deviation)
  • Bandwidth: The distance between the upper and lower bands, providing an intuitive visualization of current volatility levels

Core Validation Rules

Interpretation by Band State

Band StatePatternMeaningResponse Strategy
Band squeezeUpper and lower bands narrowingVolatility declining, major move imminentWait for breakout direction, avoid premature entry
Band expansionUpper and lower bands wideningVolatility increasing, trend strengtheningFollow the trend direction
Upper band touchPrice reaches upper bandRelatively overbought zoneAssess trend strength before acting
Lower band touchPrice reaches lower bandRelatively oversold zoneAssess trend strength before acting

Critical Exception Rules

These are essential principles to remember whenever using Bollinger Bands.

  • Upper band touch ≠ automatic sell: In a strong uptrend, price can continue rising along the upper band in a phenomenon called "Walking the Bands." Entering a short position solely because price touched the upper band can result in significant losses
  • Lower band touch ≠ automatic buy: In a strong downtrend, price can continue falling along the lower band. Buying simply because price appears "cheap" is dangerous
  • Check the middle line (20-day MA) slope: The slope of the middle line determines trend direction. If the middle line slopes upward, upper band touches signal trend continuation; if it slopes downward, lower band touches signal trend continuation

Advanced Analysis Tools

%B Indicator (Percent B)

%B quantifies where the current price stands within the bands as a value between 0 and 1 (or 0–100%).

  • Formula: %B = (Current Price − Lower Band) / (Upper Band − Lower Band) × 100
  • Interpretation:
    • %B > 100: Price has broken above the upper band (extremely bullish, band walking possible)
    • %B = 80: Near the upper band (relatively high price zone)
    • %B = 50: At the middle line (20-day MA)
    • %B = 20: Near the lower band (relatively low price zone)
    • %B < 0: Price has broken below the lower band (extremely bearish)

Bandwidth Indicator

Bandwidth is a critical tool for measuring the cycles of volatility.

  • Formula: (Upper Band − Lower Band) / Middle Line × 100
  • Application:
    • Bandwidth at 6-month low: Extremely low volatility → Squeeze state, signaling that a major move is imminent
    • Bandwidth expanding rapidly: A new trend has started or an existing trend is accelerating
    • Volatility cycles: Low volatility transitions to high volatility, and high volatility transitions to low volatility. This cyclical principle is the foundation of Bollinger Band trading

Practical Trading Strategies

W-Bottom Pattern (Bollinger Band W-Bottom)

One of the patterns Bollinger himself emphasized most, based on Arthur Merrill's W-pattern research.

  1. First bottom: Price touches or breaks below the lower band, then bounces
  2. Interim rally: Price rallies to approximately the middle line (20-day MA)
  3. Second bottom: Price declines again but does not touch the lower band (higher %B value than the first bottom)
  4. Confirmation indicators: Verify that OBV shows bullish divergence at the second bottom, or that RSI is emerging from oversold territory
  5. Entry point: Enter when price breaks above the middle line (20-day MA)

Key: The essential condition of this pattern is that the second bottom forms above the lower band.

M-Top Pattern (Bollinger Band M-Top)

The inverse of the W-Bottom, this pattern identifies top formations.

  1. First top: Price touches or breaks above the upper band, then pulls back
  2. Interim pullback: Price declines to approximately the middle line
  3. Second top: Price rallies again but does not touch the upper band (lower %B value than the first top)
  4. Confirmation indicators: If OBV shows bearish divergence at the second top, reliability increases significantly
  5. Exit point: Close positions or consider shorting when price breaks below the middle line (20-day MA)

Squeeze Breakout Strategy

This strategy captures explosive moves following volatility contraction and is particularly effective in cryptocurrency markets.

  1. Identify the squeeze: Confirm that bandwidth has reached its lowest level in the past 6 months. The longer the squeeze persists, the larger the subsequent move is likely to be
  2. Determine direction: Wait for a breakout above the upper band or below the lower band accompanied by a volume increase. Attempting to predict the direction before the breakout is risky
  3. Entry: Take a position in the breakout direction — buy on an upper band breakout, sell on a lower band breakout
  4. Target: As the bands expand, set targets at the opposite band or key support/resistance levels
  5. Stop-loss: If price returns to touch the middle line (20-day MA), consider the breakout failed and exit

Caution: A squeeze does not indicate direction. You must confirm the breakout direction before entering. To guard against fakeouts, waiting for 1–2 candles of confirmation after the initial breakout is also a sound approach.

Application by Market Environment

Range-Bound Market

  • Mean-reversion trades at the upper and lower bands are effective
  • Consider selling at %B above 80 and buying at %B below 20
  • Always verify that the middle line slope is flat. If it is angled, the market is not truly range-bound
  • Combining with oscillators such as RSI or Stochastic increases reliability
  • Follow the trend direction as the bands expand
  • Use the middle line (20-day MA) as dynamic support/resistance — consider adding to positions near the middle line on pullbacks in the trend direction
  • Avoid counter-trend trades during band walking

Parameter Adjustment Guide

Market EnvironmentMA PeriodStandard Deviation MultiplierSuitable Scenario
Default setting20 days2.0Most markets
High-volatility market20 days2.5Crypto surge/crash periods
Low-volatility market20 days1.5Extended sideways phases
Short-term trading10 days1.5Scalping / day trading
Long-term investing50 days2.5Position trading

Bollinger's recommendation: When changing the moving average period, adjust the standard deviation multiplier accordingly. Use 1.5× for a 10-day MA and 2.5× for a 50-day MA. The 20-day / 2× combination is the most versatile, so unless there is a specific reason, maintaining the default settings is advisable.

Combining with Other Indicators

  • Bollinger Bands + RSI: Lower band touch + RSI below 30 → Strong oversold signal. Upper band touch + RSI above 70 → Strong overbought signal
  • Bollinger Bands + OBV: Confirming OBV divergence during W-Bottom or M-Top patterns significantly increases pattern reliability
  • Bollinger Bands + MACD: During a squeeze, a directional shift in the MACD histogram can provide clues about the breakout direction
  • Bollinger Bands + Volume: A volume surge accompanying a band breakout confirms a genuine breakout; a breakout without volume has a high probability of reversal

Related Concepts

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