What is a stock screener and how does it work

8 min read

By SwingTradeScanner Team

A stock screener is a tool that filters the market's thousands of stocks down to a shortlist matching specific criteria such as price, volume, market cap, or technical patterns.

Think of it as a search engine for stocks. Google narrows the entire internet to the ten most relevant pages. A screener narrows the entire market to the twenty most relevant setups. If you are looking for a complete tool comparison, see our guide to the best swing trading scanner.

How a stock screener works

Every screener follows the same basic loop:

1. Data source — the screener pulls price, volume, fundamental, and sometimes alternative data for every stock in its universe.
2. Criteria — you set filters. "Show me stocks between $10 and $100 with average daily volume above 1 million and a P/E ratio under 25."
3. Output — the screener returns a list of stocks that pass every filter. You review them and decide which ones to research further.

The power of a screener is subtraction, not addition. It removes the 95% of stocks you don't care about so you can focus on the 5% that fit your strategy.

Screener vs. scanner

People use these words interchangeably, but there's a meaningful difference:

A screener is static. You set criteria, hit "screen," and get a snapshot of stocks that match right now. Finviz, Yahoo Finance, and most broker platforms work this way.

A scanner is dynamic. It runs on a schedule (or in real time) and looks for events — a breakout that just happened, a volume spike, an earnings gap. SwingTradeScanner runs seven scans nightly and catches setups as they form, not after the move is over.

If you're a swing trader, you want a scanner. By the time you manually screen for yesterday's breakout, the stock is already extended.

Common screening criteria

Price and volume

The foundation of any screen. Price between $5 and $200 eliminates penny stocks (too risky) and mega-caps (too slow). Average daily volume above 500,000 ensures you can get in and out without moving the price.

Market cap

Small caps ($300M–$2B) are volatile and catalyst-driven. Mid caps ($2B–$10B) balance volatility with stability. Large caps ($10B+) move slowly but offer more predictable trends. Most swing traders focus on mid caps. For more on choosing the right names, see best stocks for swing trading.

Technical criteria

Stocks near 52-week highs, stocks above their 50-day and 200-day moving averages, stocks with rising relative strength. These filters find stocks in uptrends where breakouts are more likely to follow through.

Fundamental criteria

Earnings growth above 20%, revenue acceleration, positive cash flow. Fundamentals separate stocks that break out and keep going from stocks that break out and fade. The CANSLIM scan combines fundamental and technical criteria in one screen.

Catalyst criteria

This is where most screeners fall short. A stock can meet every technical and fundamental filter and still go nowhere without a catalyst. Earnings beats, FDA approvals, new contracts, and SEC filings are the events that trigger moves. SwingTradeScanner's episodic pivot scan specifically screens for catalyst-driven gaps.

How to build your first screen

1. Start with your strategy. Are you looking for breakouts, mean reversion, earnings plays, or sector rotation? The strategy dictates the criteria.
2. Set broad filters first. Price, volume, and market cap eliminate most of the universe immediately.
3. Add technical filters. Trend direction, proximity to highs, relative strength.
4. Add fundamental filters if your strategy requires them. Not every setup needs earnings data.
5. Review the output. If you get 200 results, your criteria are too loose. If you get 0, they're too tight. Aim for 10–30 candidates per day. Then build a focused swing trading watchlist from the output.

Ready to go beyond static screens? The SwingTradeScanner dashboard runs seven dynamic scans with catalyst detection built in.

Types of screening criteria

Every screen is built from criteria, and those criteria fall into three categories. Understanding each one helps you build screens that actually find tradeable setups instead of random lists of stocks.

Fundamental criteria

Fundamental criteria measure the health and trajectory of the underlying business. The most useful ones for swing trading include P/E ratio, PEG ratio, earnings growth rate (both quarterly and annual), revenue growth, profit margins, return on equity, and debt-to-equity ratio.

These numbers tell you whether the business is improving. The single most important signal is accelerating earnings — quarter-over-quarter growth that is increasing, not just positive. Stocks showing this acceleration often attract institutional buying volume. A company that grew earnings 15% last quarter and 25% this quarter is accelerating. That acceleration is what attracts institutional buyers and produces the biggest stock moves.

Revenue growth confirms that earnings growth is real and not just the result of cost cutting. Profit margin expansion on top of revenue growth is even better — it means the company has pricing power or operating leverage. The CANSLIM screening framework formalizes these fundamental criteria into a repeatable checklist.

Technical criteria

Technical criteria describe where the stock price is relative to its own history and how it is behaving right now. The most common technical filters include price relative to moving averages (50-day and 200-day), proximity to the 52-week high, relative strength rating, average daily range (ADR%), and volume patterns.

Technical criteria find stocks in confirmed uptrends where breakouts are more likely to work. A stock trading above its rising 50-day and 200-day moving averages, within 25% of its 52-week high, with a relative strength rating in the top decile of the market, is in a strong uptrend. Breakouts from tight consolidation patterns in these stocks have a much higher success rate than breakouts in stocks that are still trying to recover from a downtrend.

The SEPA trend template is the most rigorous set of technical criteria for confirming that a stock is in the right stage of its price cycle for a swing trade entry.

Hybrid criteria

The most effective screens combine both fundamental and technical criteria. A stock trading above its 50-day moving average with 25%+ quarterly earnings growth and volume running 1.5x its 20-day average is a fundamentally strong stock in a technical uptrend with institutional interest. That combination is far more predictive than either category alone.

This hybrid approach is the foundation of the CANSLIM and SEPA methodologies. It is also what SwingTradeScanner's scans are built on. Every scan combines price action, trend position, fundamental momentum, and volume behavior into a single filter set. You do not have to decide between fundamental and technical screening — the scan does both.

Filter logic: AND vs OR

Most screeners use AND logic by default. Every criterion must pass for a stock to appear in the results. If you set three filters — price above $10, earnings growth above 20%, and volume above 500,000 — a stock must meet all three to show up. AND logic narrows results quickly, which is usually what you want.

Some advanced screeners also support OR logic, where a stock passes if it meets criterion A or criterion B. OR logic is useful when you want to capture multiple setup types in one scan. For example, you might want stocks that either gapped up 5% on an earnings surprise or broke out of a VCP pattern on above-average volume. Both are valid swing trade entries, but they require completely different criteria. You cannot combine them in a single AND screen without making the filters so loose that noise floods the results.

SwingTradeScanner solves this by running seven separate scans, each with its own AND logic, rather than one screen that tries to do everything. The SEPA scan looks for trend template stocks. The episodic pivot scan looks for catalyst gaps. The CANSLIM scan checks fundamental acceleration. Each scan is tight and specific. The combined output covers multiple setup types without compromising any individual screen's precision.

Common screening mistakes

Over-optimizing for past results

It is tempting to tweak your filters until they perfectly match last year's biggest winners. If you adjust enough variables, you can build a screen that would have caught every 200% gainer in 2024. The problem is that this is curve fitting. You are fitting your criteria to noise, not signal. The market environment changes — sector leadership rotates, volatility regimes shift, interest rate cycles turn. Criteria that caught 2024's leaders will not necessarily catch 2025's. Build screens around structural principles (strong earnings, confirmed uptrend, increasing volume) rather than backward-looking parameter optimization.

Ignoring liquidity

A stock can pass every fundamental and technical filter you set, but if it trades 50,000 shares a day, it will cost you real money on entry and exit. Thin stocks have wide bid-ask spreads, and your market orders will move the price against you. Limit orders might not fill at all during a fast breakout. Always include a volume floor in your screens — 200,000 shares minimum daily average volume for swing trading, ideally 500,000 or more. The lost opportunities from filtering out illiquid stocks are nothing compared to the slippage costs of trading them.

Running screens without checking the market

In a broad market decline, even the best screens produce false positives. Stocks that pass your trend and momentum filters during a correction are often the last holdouts before they break down too. Before acting on any scan result, check market breadth. How many stocks are above their 50-day moving average? Is the advance-decline line rising or falling? Is the number of new highs expanding or contracting? If the market environment is hostile, your screen results are suspects, not candidates. Read more about how to read market breadth before trading any scan output.

Confusing a screen result with a buy signal

Passing a screen means a stock is worth looking at. It does not mean you should buy it. The screen is step one in a multi-step process. After the screen, you need to read the chart and identify a specific entry setup — a breakout from a base, a pullback to support, an episodic pivot. Then you need to size the position based on your stop distance and account risk. Then you need to define where you are wrong and where you will exit. Skipping any of these steps turns a disciplined process into a coin flip. For a complete guide to what comes after the screen, see swing trading risk management.

General screeners vs methodology-specific scanners

General screeners like Finviz, TradingView, and Yahoo Finance let you set any combination of filters from a broad menu. They are flexible and most offer a free tier. The tradeoff is that they require you to know exactly what to look for. You have to decide which criteria to use, what thresholds to set, and how to combine them. If you set them wrong, you get noise. If you set them right, you still need to do the work of interpreting the output. None of these platforms detect SEC filing catalysts, flag dilution risk from shelf registrations, or score results by setup quality. They give you a list of tickers; the due diligence is entirely on you.

Methodology-specific scanners like SwingTradeScanner are pre-configured around a proven trading framework. The SEPA scan applies Minervini's trend template automatically. The episodic pivot scan looks for Qullamaggie-style catalyst gaps with live premarket data starting at 4:00 AM ET. The CANSLIM scan follows O'Neil's criteria for earnings acceleration and institutional sponsorship. You do not have to build the screen yourself or wonder if you set the right thresholds. The scan is the methodology, automated. Each result includes a composite score, RS rank, catalyst classification, and SEC filing check -- layers of context that general screeners simply do not provide.

The cost difference is worth noting. TradingView Pro runs $30/month and still requires you to build every screen from scratch. MarketSurge costs $45/month. Trade Ideas starts at $118/month. SwingTradeScanner delivers seven methodology-specific scans with built-in catalyst detection and relative strength rankings for $20/month, with a free 7-day trial that requires no credit card. For traders who follow a specific method -- and the most consistent traders do -- it is the most complete and affordable option available. For a deeper look at how these two approaches differ, read stock scanner vs stock screener.

Questions