What Is a Stock Scanner? How Traders Find Opportunities Fast

Stock Scanner Defined

A stock scanner (also called a stock screener) is software that filters securities based on user-defined criteria. Instead of manually reviewing thousands of stocks, you set parameters—and the scanner returns matches in seconds.

Why Scanners Are Essential

US markets have 10,000+ tradeable securities. Manual review is impossible. Scanners allow you to:

• Find opportunities you would have missed

• Apply consistent criteria systematically

• React quickly when setups appear

• Save hours of manual research

Types of Scanners

Filter-Based Scanners

The traditional model: you define criteria (price > $10, volume > 1M, RSI < 30), and the scanner returns all matching stocks. Examples: Finviz, TradingView Screener.

Signal-Based/Curated Scanners

Instead of you defining filters, algorithms score every asset and surface top opportunities in a ranked list. You see what's showing the strongest signals right now. Example: Banana Farmer's leaderboard approach.

AI-Powered Scanners

Use machine learning to identify patterns and predict opportunities. More complex, often more expensive. Example: Trade Ideas' Holly AI.

Common Screening Criteria

Technical

• Price action (52-week high/low, % change)

• Volume (average, relative, spikes)

• Moving averages (price above/below, crossovers)

• Indicators (RSI, MACD levels)

Fundamental

• Valuation (P/E, P/B, PEG)

• Growth (revenue growth, EPS growth)

• Size (market cap)

• Profitability (margins, ROE)

Alternative Data

• Social sentiment (trending mentions, sentiment scores)

• News (recent releases, analyst changes)

• Insider activity

Popular Stock Scanners

• Finviz: Comprehensive free screener, good for fundamentals and technicals

• TradingView: Integrated with best-in-class charting

• Trade Ideas: AI-powered, professional-grade, premium priced

• Banana Farmer: Social sentiment + technical signals, curated leaderboard

How to Use a Scanner Effectively

1. Define your strategy first (what are you looking for?)

2. Start with simple criteria (2-3 filters)

3. Aim for 10-50 results (manageable for review)

4. Always verify on charts (scans are starting points, not signals)

5. Refine based on results (which criteria lead to good trades?)

Scanners vs. Manual Research

Scanners don't replace thinking—they replace tedious searching. The scanner finds candidates; you analyze them. The scanner surfaces opportunities; you decide which to take. It's a tool, not a strategy.