Market Breadth Analysis Methodology

Market Breadth Analysis Methodology

Overview

Market breadth measures the degree of participation in a market move. A healthy advance is characterized by broad participation (many stocks rising), while a narrowing market (fewer stocks leading) often precedes corrections.

This methodology uses TraderMonty's breadth dataset to quantify market health across 6 dimensions, producing a composite score from 0 (critical) to 100 (maximum health).

Data Description

Breadth Index

The breadth index (0-1) measures the proportion of S&P 500 stocks trading above their 200-day moving average. Key derivatives:

• Raw: Daily breadth value (percentage of stocks above 200DMA)
• 8-day EMA (8MA): Short-term exponentially weighted moving average (fast signal)
• 200-day EMA (200MA): Long-term exponentially weighted moving average (trend filter)

Important: Both moving averages use EMA (Exponential Moving Average), not SMA. The source repository calculates them as ewm(span=N, adjust=False). EMA gives more weight to recent data points, making it more responsive to changes than SMA.

Key Thresholds

Signal Flags

• Breadth_200MA_Trend: 1 = 200MA rising (bullish regime), -1 = 200MA falling (bearish regime). Uses hysteresis with threshold=0.001 to prevent whipsaw signals.
• Bearish_Signal: Backtested signal combining trend and momentum deterioration
• Is_Peak / Is_Trough: Cyclical turning points detected using scipy.signal.find_peaks with distance=50, prominence=0.015 on the 200MA. This ensures at least 50 trading days (~10 weeks) between consecutive peaks/troughs and a minimum prominence of 0.015.
• Is_Trough_8MA_Below_04: Extreme trough marker detected with prominence=0.02 on inverted 8MA values below 0.4.

Pink Zone (Bearish Region)

The source repository's charts use a pink background to highlight the most dangerous market condition:

Pink Zone = (Breadth_200MA_Trend == -1) AND (8MA < 200MA)

This means the long-term trend is declining AND the short-term breadth has fallen below the long-term average. Historically, markets in the Pink Zone experience elevated volatility and downside risk. The Pink Zone is distinct from the Bearish_Signal flag - it is a structural condition that can persist for weeks or months.

Component Details

C1: Current Breadth Level & Trend (25%)

Rationale: The most direct measure of current market health. Higher 8MA means more stocks participating; uptrend in 200MA means the long-term structure is supportive.

Weighting within component:

• 8MA Level: 70% - immediate health snapshot
• 200MA Trend: 30% - longer-term regime confirmation

Key insight: An 8MA of 0.65 in an uptrend (score ~80) is healthier than 0.65 in a downtrend (score ~62), because the downtrend context suggests the level may be transient.

C2: 8MA vs 200MA Crossover Dynamics (20%)

Rationale: The gap between fast and slow MAs reveals momentum. A wide positive gap means breadth is accelerating above trend; a negative gap means it's deteriorating below trend.

Direction modifier: When the 8MA is recovering (rising) while still below the 200MA, this early recovery signal adds +10. Conversely, when 8MA is falling while still above 200MA, this early deterioration signal subtracts -10.

Key insight: The crossover point (8MA crossing 200MA) is a significant signal. Bull markets maintain 8MA above 200MA; bear phases see 8MA below 200MA.

C3: Peak/Trough Cycle Position (20%)

Rationale: Breadth moves in cycles. Knowing whether we are in the early, middle, or late phase of a cycle helps calibrate expectations.

Cycle phases:

1. Trough → Early Recovery (0-20 days): Highest potential for upside if 8MA is rising
2. Sustained Recovery (21-60 days): Confirmed recovery with decreasing upside magnitude
3. Mature Recovery (60+ days): Late-cycle, watch for next peak
4. Post-Peak Decline (0-20 days): Highest risk period
5. Sustained Decline (21-60 days): Deep correction territory
6. Prolonged Decline (60+ days): Potential bottom formation if 8MA starts rising

Extreme trough bonus: When 8MA drops below 0.4 at a trough, history shows these are often excellent long-term entry points, warranting a +10 bonus.

C4: Bearish Signal Status (15%)

Rationale: The dataset includes a backtested bearish signal flag that combines multiple factors. Its value depends on context.

Interpretation matrix:

Context matters: A bearish signal when 8MA is above 0.50 is less concerning (+15 adjustment) than one when 8MA is below 0.25 (-5 adjustment).

Pink Zone integration: When in the Pink Zone (200MA downtrend + 8MA below 200MA) but without an active bearish signal, a -10 penalty is applied to reflect structural weakness that the bearish flag alone may not capture.

C5: Historical Percentile (10%)

Rationale: Knowing where current breadth stands relative to the full 10-year history provides framing. Is this level normal, unusually high, or unusually low?

Overheated/oversold adjustments: When current 8MA approaches the average peak level, a -10 penalty reflects elevated risk of mean reversion. When near the average trough level, a +10 bonus reflects contrarian opportunity.

C6: S&P 500 vs Breadth Divergence (10%)

Rationale: The most dangerous market condition is when the index makes new highs but breadth is declining (fewer stocks participating). This divergence preceded major tops in 2000, 2007, and 2021.

Key patterns:

• S&P up + Breadth up: Healthy, sustainable rally (70)
• S&P up + Breadth down: Dangerous narrow market (10-25)
• S&P down + Breadth up: Bullish divergence, potential bottom (65-80)
• S&P down + Breadth down: Consistent decline, wait for stabilization (30)

Composite Score Interpretation

Zone Thresholds

Cross-Referencing with Other Skills

• Market Top Detector: If breadth is Weakening (20-39) AND top detector is Orange/Red, this is strong confirmation of topping conditions.
• CANSLIM Screener: In Strong/Healthy zones, CANSLIM stock selections have higher success rates.
• Sector Analyst: Weakening breadth often coincides with rotation from offensive to defensive sectors.

Historical Context

Average Values (from Summary CSV)

• Average Peak (200MA): ~0.729 - breadth cycles typically top around this level
• Average Trough (8MA < 0.4): ~0.232 - extreme troughs average around this level
• Peak Count: ~5 over 10 years (roughly every 2 years)
• Trough Count: ~10 extreme troughs (roughly twice per year on average)

Notable Historical Patterns

• COVID-19 (March 2020): 8MA crashed to extreme lows, followed by one of the sharpest breadth recoveries in history
• 2022 Bear Market: Sustained period of 8MA below 200MA with multiple bearish signals
• 2023 Recovery: Gradual breadth improvement with 8MA crossing above 200MA

Live Resources

• Interactive Dashboard: https://tradermonty.github.io/market-breadth-analysis/
• Data CSV: https://tradermonty.github.io/market-breadth-analysis/market_breadth_data.csv
• Summary CSV: https://tradermonty.github.io/market-breadth-analysis/market_breadth_summary.csv
• Source Repository: https://github.com/tradermonty/market-breadth-analysis

Data is automatically updated twice daily via GitHub Actions. CSV files are freely accessible without API keys.

Limitations

1. Lagging indicator: Breadth data reflects what has happened, not what will happen. Use alongside forward-looking indicators.
2. No sector granularity: The breadth index is market-wide. A few large sectors can dominate the reading.
3. CSV update frequency: Data depends on TraderMonty's update schedule. Check data freshness before analysis.
4. Single market: Covers S&P 500 only. Does not reflect international markets, small caps, or other asset classes.
5. No volume context: The breadth index is price-based and does not incorporate volume data.