What Is a Stock Screener? One Real Screen of 6,938 US Listings, Step by Step
Michael Whitman
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Trading since 2017, full-time since 2020
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YouTube creator, 137K subscribers
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Published 2026-09-15
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Updated
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Reviewed
Stock screener is a tool that filters a universe of listed companies down to those meeting stated numerical conditions, such as size, volume, valuation or price relative to an average. It narrows a field to a shortlist, and because you write the conditions, the shortlist reflects your assumptions.
Covered on this page: Finviz and TradingView.
A stock screener is a tool that filters every listed stock down to the ones that meet numerical rules you set, such as size, trading volume or price against an average. Run on 23 Oct 2026, two plain filters cut 6,938 US listings to 1,243, and one technical condition halved that again.
How it works
Start with a universe. Every US-listed stock, or a market, or an index — the set you are willing to consider at all.
Apply conditions. Market cap above a number, volume above another, price above a moving average, a valuation ratio below a threshold.
What survives is the shortlist. Not the best stocks — the ones matching conditions you specified, which is a different claim.
Why the filters matter more than the tool
Screeners differ mostly in data coverage, update timing and interface. The arithmetic of “market cap above $2 billion” is the same everywhere.
So the tool is rarely the variable. Two people with the same screener and different filters get completely different lists, and the difference is entirely in what they asked for.
Which makes “best screener settings” a strange phrase. Best for what holding period, what account size, what market? A setting is only best relative to a purpose somebody stated.
A worked example: one real screen
The universe: Nasdaq’s screener download of every US listing, 6,938 rows. That count includes common stocks, depositary receipts, preferred shares, closed-end funds, warrants, units and rights, but not exchange-traded funds, and 5,767 of them carry a market value.
Filter one, market cap of $2 billion or more: 2,132 remain (30.73%).
Filter two, at least 1,000,000 shares traded in the session: 1,243 remain (17.92%). The two filters together removed 82.08% of the list, and neither is clever. They are aimed at the names where the spread and the slippage tend to be largest.
Filter three, a technical condition: last close above the average of its last 200 closes. 29 of the 1,243 had fewer than 200 sessions of history and could not be tested; of the other 1,214, 613 passed (50.49%).
Filter four, a close within 5% of the highest close of the past 252 sessions to 23 Oct, roughly a year of Yahoo Finance daily closes. Three of the 613 had too short a history; of the other 610, 210 passed (34.43%). This is the kind of “near the high” condition momentum screens use, and it cut harder than the average did.
Each further condition keeps cutting. Add six more and a list like this can fall to a handful of names that satisfy a very specific description of the past, and the specificity came from you rather than from the market.
Common filters and what each one measures
Most screeners offer dozens of fields, but they fall into a handful of families. The update column matters as much as the definition, because a filter can only be as fresh as the number behind it.
| Filter | What it measures | How often the number changes |
|---|---|---|
| Market cap | Share price times shares outstanding | Every trade, through the price |
| Volume or relative volume | Shares traded, alone or against the stock’s own average | Every session |
| P/E ratio | Price against the last reported earnings per share | Price daily, earnings each quarter |
| Dividend yield | Yearly dividends as a share of price | Price daily, dividend when declared |
| Debt-to-equity | Borrowing against shareholders’ equity | Each quarterly report |
| Price vs 200-day average | Where the close sits against its long average | Every session |
| RSI | Recent gains against recent losses, 0 to 100 | Every session (or bar, intraday) |
| 52-week high or low | Distance from the year’s extremes | Every session |
Mixing the slow rows with the fast ones is where most screens get confused, which the fundamental versus technical section below takes up.
The two filters that earn their place
Volume. Heavily traded stocks tend to quote narrow spreads. In a thin stock the spread can be many times wider, and it is paid on every trade whether the idea works or not. The liquidity page covers why.
Market capitalization. Smaller companies tend to have wider spreads, thinner books and larger gaps, so a size floor is a liquidity filter wearing different clothes.
Everything else is preference. Valuation ratios, technical conditions, sector exclusions — all reasonable, none as consequential as making sure you can get in and out at a sane price.
The original data
The screen above ran on Nasdaq’s stock screener download, every US-listed stock with its last sale, volume and market value. The file was downloaded early on 27 Oct 2026, a Tuesday, and still held Friday’s session: every one of the 1,243 survivors’ last sales matched Yahoo Finance’s 23 Oct close to the cent, and every volume matched Yahoo’s 23 Oct volume within 1%. Nothing in the file says so; the dates had to be matched.
| Step | Condition | Listings left |
|---|---|---|
| 0 | Every listing in the download | 6,938 |
| 1 | Market cap $2 billion or more | 2,132 |
| 2 | And 1,000,000 shares or more traded on 23 Oct | 1,243 |
| 3 | And 200 sessions of history | 1,214 |
| 4 | And last close above its 200-session average | 613 |
| 5 | And 252 sessions of history, close within 5% of the 252-session closing high | 210 of 610 |
One day’s volume is not average volume. Of the 1,243 that traded a million shares on 23 Oct, 1,182 also averaged a million over their last 20 sessions; 61 cleared the bar on that day only. A screen run on a single session’s volume lets a busy day stand in for a liquid stock.
The 200-session condition split the list almost exactly in half, 613 of 1,214. A condition that keeps half of what it sees is a sorting rule, not a discovery. Every survivor, its volume, its 20-session average and its 200-session average are in the screen file.
Of the 24,971 trading and investing videos measured for this site, 41 have “stock screener” in the title, from 34 channels, at a median of 9,979 views.
Screening without fooling yourself
Write the filters before looking at results. Adjusting conditions until the list contains names you already liked is not screening, it is confirmation with extra steps.
Keep the screen fixed for a period. A saved screen run weekly produces a comparable series of outputs; one edited each week produces nothing you can learn from.
Record what you did with the output. Screens are testable — did the names you took actually behave differently from the ones you skipped? — and almost nobody checks.
And accept that a screen cannot tell you why. It knows a company’s price is above an average; it does not know the company is under investigation, has lost a contract, or is about to report. That part is reading, and the screen exists to make the reading list short enough to do.
Screener or scanner?
The words overlap, and many tools use them interchangeably. In common use, a screener runs a fixed set of conditions over a whole universe when you ask, often on end-of-day data, and returns a list. A scanner usually means the same idea run continuously during the session, flagging names the moment they meet a condition such as unusual volume or a new high.
The practical difference is the clock. A screen run on Sunday describes Friday; a live scan describes the last few seconds, which is why scanners lean on price and volume conditions and rarely on quarterly fundamentals.
Fundamental screens versus technical ones
A fundamental screen filters on company facts - revenue growth, margins, debt, valuation ratios. Those update only when a company reports, so the screen’s answers change four times a year rather than daily.
A technical screen filters on price and volume behavior - above an average, near a high, unusual volume. Those change every session, so the same screen returns a different list each morning.
They answer different questions and are often combined badly. A screen mixing quarterly fundamentals with a daily price condition is asking about two timescales at once, and the fast condition drives almost all of the turnover in the list.
The cleaner approach is sequencing. Use fundamentals to build a universe you would be willing to own, then use technicals to decide when to look at it - rather than requiring both to be true on the same morning. The output feeds a watchlist, not an order.
Why a screen is not a backtest
A screen tells you what is true right now. It has no memory and makes no claim about what happened after previous times the condition held.
That is the distinction people skip. “Stocks above their 200-day average” is a fact about today; “stocks above their 200-day average outperformed” is a claim about history that a screener has not checked and cannot check.
Which is why tightening a screen feels like research and is not. Adding conditions until the list is short produces a very specific description of the present, and specificity is not evidence.
A backtest asks the other question. Given this condition, what happened next, across many instances, including the ones you would rather forget. That requires historical data and a rule applied without hindsight.
When it fails
The characteristic failure is filtering until the answer is comfortable. The list comes back at two hundred names, which feels like too much work, so conditions are added — each defensible in isolation — until five names remain. Those five now match an extremely specific description of what already happened, and the tightening was driven by wanting a shorter list rather than by any belief about what matters.
A second failure is screening without a liquidity floor, which fills the list with names that are expensive to trade. Without the two plain filters, the screen above would have started from 6,938 rows instead of 1,243.
A third is treating the output as recommendations. It is a reading list.
A fourth is changing the filters weekly, which destroys any ability to judge whether they work.
And a fifth is assuming the data is current. The download used here, taken on a Tuesday morning, still described Friday’s session, and fundamentals update only when a company reports.
Questions people ask
What does a stock screener do?
It filters every stock in a universe down to the ones meeting the conditions you set, such as market value, volume or price against an average. On 23 Oct 2026, a $2 billion size floor and a million shares of volume took 6,938 US listings down to 1,243.
What are good stock screener settings for beginners?
Start with the two plain filters, a size floor and a volume floor, because they remove the names that are costly to trade. Anything after that depends on what you are looking for, and should be written down before you see the results.
Is a stock screener a buy list?
No. It is a list of stocks matching a description you wrote. A condition such as “above the 200-day average” kept 613 of 1,214 names on 23 Oct 2026, which says nothing about which of them go on to rise.
Are stock screeners free?
Many are. Most online brokers include one, and several finance sites offer a free tier; paid tiers usually add real-time data, more fields or saved alerts. The screen in this page used Nasdaq’s free download.
Are stock screener prices real-time?
Not always. A Nasdaq screener download taken early on a Tuesday still held Friday’s last sales, and many free tiers show delayed prices. Check the date the data describes before acting on it.
Related
How to use a stock screener walks through setting up and saving a screen. Finviz covers the screener most people start with. Liquidity covers why the volume filter matters most. And build a watchlist covers what to do with the shortlist.
A screener does not find opportunities. It finds stocks matching a description you wrote, which means the quality of the output is entirely the quality of the description. Most people spend their time on exotic filters when the two that matter are size and volume.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money. Some links on this page earn a commission if you buy through them. It costs you nothing and it does not decide what appears here or in what order — how these pages are made is set out in our methodology.