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Downtrend Duration Analyzer

  • 722 installs
  • 2.6k repo stars
  • Updated August 4, 2026
  • tradermonty/claude-trading-skills

downtrend-duration-analyzer is a Claude Code trading skill that measures how long market downtrends persist for developers and quants who calibrate timing, risk, and systematic trading rules.

About

downtrend-duration-analyzer is a skill in tradermonty/claude-trading-skills focused on quantifying downtrend length from price series so trading logic can use duration statistics instead of guesswork. Developers reach for downtrend-duration-analyzer when backtesting strategies, building alert conditions, or documenting regime behavior where knowing typical downtrend spans improves stop placement and re-entry timing. The skill fits agent sessions analyzing OHLCV or tick-derived series where the goal is structured duration metrics, histograms, or threshold recommendations rather than generic chart commentary. Use it when duration distributions should inform position sizing or filter rules in automated trading code.

  • downtrend-duration-analyzer

Downtrend Duration Analyzer by the numbers

  • 722 all-time installs (skills.sh)
  • +90 installs in the week ending Aug 5, 2026 (Skillselion tracking)
  • Ranked #515 of 4,347 Backend & APIs skills by installs in the Skillselion catalog
  • Data as of Aug 5, 2026 (Skillselion catalog sync)
npx skills add https://github.com/tradermonty/claude-trading-skills --skill downtrend-duration-analyzer

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Listed on Skillselion
Installs722
repo stars2.6k
Last updatedAugust 4, 2026
Repositorytradermonty/claude-trading-skills

How do you measure how long market downtrends last?

Use downtrend-duration-analyzer for development tasks

Who is it for?

Developers building or tuning systematic trading strategies who need empirical downtrend duration metrics inside Claude sessions.

Skip if: Developers seeking fundamental equity research, portfolio accounting, or non-trading application backend work.

When should I use this skill?

The user asks how long downtrends typically last, wants duration stats for a symbol, or needs downtrend timing for a trading strategy.

What you get

Downtrend duration statistics, threshold recommendations, and analysis notes tied to price series segments.

  • downtrend duration statistics
  • strategy threshold recommendations

Files

SKILL.mdMarkdownGitHub ↗

Downtrend Duration Analyzer

Overview

Analyze historical price data to identify downtrend periods (peak-to-trough) and build statistical distributions of correction durations. Generate interactive HTML visualizations with histograms segmented by sector and market cap to help traders understand typical recovery timeframes and set realistic expectations for mean reversion strategies.

When to Use

  • Trader asks about typical correction lengths for a sector or market cap tier
  • User wants to understand historical drawdown recovery times
  • Building mean reversion or pullback strategies that need realistic holding period estimates
  • Comparing correction behavior across different market segments
  • Setting stop-loss timeouts or position holding period limits

Prerequisites

  • Python 3.9+
  • FMP API key (set FMP_API_KEY environment variable or use --api-key)
  • Required packages: requests, pandas, numpy (standard data analysis stack)

Workflow

Step 1: Fetch Historical Price Data

Run the analysis script to fetch OHLC data for a universe of stocks and identify downtrend periods.

python3 skills/downtrend-duration-analyzer/scripts/analyze_downtrends.py \
  --sector "Technology" \
  --lookback-years 5 \
  --output-dir reports/

Step 2: Analyze Downtrend Durations

The script automatically: 1. Identifies local peaks and troughs using rolling window analysis 2. Calculates duration (trading days) and depth (% decline) for each downtrend 3. Segments results by sector and market cap tier (Mega, Large, Mid, Small) 4. Computes summary statistics (median, mean, percentiles)

Step 3: Generate Interactive HTML Visualization

python3 skills/downtrend-duration-analyzer/scripts/generate_histogram_html.py \
  --input reports/downtrend_analysis_*.json \
  --output-dir reports/

This creates an interactive HTML file with:

  • Histogram of downtrend durations
  • Filters for sector and market cap
  • Hover tooltips with percentile information
  • Summary statistics table

Step 4: Review Distribution Insights

Load the generated markdown report to interpret the findings:

  • Short corrections (5-15 days): Typical pullbacks within uptrends
  • Medium corrections (15-40 days): Standard sector rotations
  • Extended corrections (40+ days): Trend changes or bear markets

Output Format

JSON Report

{
  "schema_version": "1.0",
  "analysis_date": "2026-03-28T07:00:00Z",
  "parameters": {
    "lookback_years": 5,
    "sector_filter": "Technology",
    "peak_window": 20,
    "trough_window": 20
  },
  "summary": {
    "total_downtrends": 1234,
    "median_duration_days": 18,
    "mean_duration_days": 24.5,
    "p25_duration_days": 10,
    "p75_duration_days": 32,
    "p90_duration_days": 55
  },
  "by_sector": {
    "Technology": {
      "count": 456,
      "median_days": 15,
      "mean_days": 20.3
    }
  },
  "by_market_cap": {
    "Mega": {"count": 200, "median_days": 12},
    "Large": {"count": 300, "median_days": 16},
    "Mid": {"count": 400, "median_days": 22},
    "Small": {"count": 334, "median_days": 28}
  },
  "downtrends": [
    {
      "symbol": "AAPL",
      "sector": "Technology",
      "market_cap_tier": "Mega",
      "peak_date": "2025-01-15",
      "trough_date": "2025-02-10",
      "duration_days": 18,
      "depth_pct": -12.5
    }
  ]
}

Markdown Report

# Downtrend Duration Analysis

**Date**: 2026-03-28
**Lookback**: 5 years
**Sector**: Technology

## Summary Statistics

| Metric | Value |
|--------|-------|
| Total Downtrends | 1,234 |
| Median Duration | 18 days |
| Mean Duration | 24.5 days |
| 25th Percentile | 10 days |
| 75th Percentile | 32 days |
| 90th Percentile | 55 days |

## By Market Cap Tier

| Tier | Count | Median | Mean |
|------|-------|--------|------|
| Mega ($200B+) | 200 | 12 days | 15.2 days |
| Large ($10-200B) | 300 | 16 days | 20.1 days |
| Mid ($2-10B) | 400 | 22 days | 28.4 days |
| Small (<$2B) | 334 | 28 days | 35.6 days |

## Key Insights

1. Larger companies recover faster from corrections
2. Technology sector shows shorter median correction than market average
3. 90% of corrections resolve within 55 trading days

HTML Visualization

Interactive histogram saved to reports/downtrend_histogram_YYYY-MM-DD.html with:

  • Plotly.js-based interactive charts
  • Sector and market cap dropdown filters
  • Duration distribution with bin controls
  • Percentile markers (P25, P50, P75, P90)

Reports are saved to reports/ with filenames:

  • downtrend_analysis_YYYY-MM-DD_HHMMSS.json
  • downtrend_analysis_YYYY-MM-DD_HHMMSS.md
  • downtrend_histogram_YYYY-MM-DD_HHMMSS.html

Resources

  • scripts/analyze_downtrends.py -- Main analysis script for fetching data and computing downtrend durations
  • scripts/generate_histogram_html.py -- HTML visualization generator with interactive histograms
  • references/downtrend_methodology.md -- Peak/trough detection algorithms and market cap tier definitions

Key Principles

1. Statistical Rigor: Use robust peak/trough detection to avoid noise-induced false signals 2. Segmentation Matters: Always analyze by sector and market cap; averages hide important differences 3. Realistic Expectations: Use percentiles (not just means) to understand the full distribution of outcomes

Related skills

How it compares

Use downtrend-duration-analyzer for duration-specific regime stats; use general indicator skills when you only need moving averages or momentum signals.

FAQ

What does downtrend-duration-analyzer output?

downtrend-duration-analyzer outputs downtrend length statistics and timing insights derived from price series segments. Developers use those metrics to set stop distances, re-entry rules, and alert thresholds in systematic trading code.

When should developers invoke downtrend-duration-analyzer?

Developers should invoke downtrend-duration-analyzer when backtesting or refining strategies that depend on how long selloffs persist. The skill focuses on empirical duration measurement rather than discretionary narrative chart analysis.

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