There are thousands of listed companies, far too many to read about one by one. A stock screener narrows the list to companies that meet conditions you choose, such as a P/E below 15 or little debt. This article explains how screeners work, how each condition narrows the list, using real counts from PositoAI's data, and the limits to keep in mind.
What a screener does
A screener is a filter. You pick one or more measures, set a limit for each, and the screener returns every company that passes all of them. It does not judge companies; it only sorts them by the rules you give it. The result is a shorter list to study further, not a list of answers.
Common screening measures
Valuation: P/E and P/B, for companies priced low or high compared with profit or net worth.
Profitability: return on equity (ROE) and profit margins.
Debt: debt-to-equity or PositoAI's Owes vs Owns figure.
Income: dividend yield.
Size: market value, from very small to very large companies.
Example on PositoAI: how many companies pass one condition
On 20 Oct 2026, among 2,078 ranked Indian companies on PositoAI, 553 had a P/E below 15, 585 had an ROE of 15% or more, 1,310 owed less than half of what they owned, and 192 had a dividend yield of 2% or more.
Among 3,582 ranked US companies, the counts were 784, 809, 1,677 and 900. Dividends of 2% or more were far more common in the US: about one company in four, against fewer than one in ten in India. (As on 20 Oct 2026; counts change daily.)
Each condition narrows the list
Adding conditions one at a time shows how quickly a list shrinks. A single condition often leaves hundreds of companies; three conditions together can leave a manageable number to study.
Example on PositoAI: three conditions together
In India, 553 ranked companies had a P/E below 15. Adding ROE of 15% or more left 188, and adding Owes vs Owns below 0.5 left 105. In the US, the same three steps went from 784 to 321 to 117 companies. (As on 20 Oct 2026.)
How to set sensible limits
Start broad. Very tight limits can leave almost nothing, or only unusual cases.
Think about the industry. Banks naturally show high Owes vs Owns figures and low P/B; software companies show the reverse. A screen that mixes all industries can quietly exclude whole sectors.
Use limits that match the question. If the aim is companies with steady income, dividend yield and low debt fit better than P/E alone.
The limits of screening
Numbers are backward-looking. A screen uses the latest reported figures, which may already be changing.
Odd figures pass easily. A one-off gain can make P/E look very low; very small net worth can make ROE look very high. Such companies often pass screens for the wrong reasons.
Missing data drops companies out. A company without a figure for a measure will not appear in a screen using it.
A screen is a start. Each company on the list still needs a look at its business, cash, debt and history.
Common misconceptions
"Companies that pass a screen are good investments." They only meet the chosen numbers; the reasons behind those numbers still need checking.
"More conditions give better results." Too many conditions can leave only unusual companies or none at all.
"Screens work the same in every country." Typical levels of P/E, debt and dividends differ by market, as the counts above show.
Frequently asked questions
What is a good first screen?
One or two conditions, such as low debt and positive profit, then a closer look at the companies that remain.
Why do some well-known companies not appear?
They may miss one limit narrowly, or have a figure missing.
How often do screen results change?
Daily, as share prices move, and after each new set of results.
Should I screen across all industries?
It works for a first look, but comparing within one industry is usually fairer.
How to use this on PositoAI
The Screeners page has ready lists such as Low P/E, High ROE, Low Debt and High Dividend Yield, each with a country filter. The custom screener combines P/E, P/B, debt-to-equity, Positivity Score, country and company size. The Top 10 lists rank companies within each country. PosiStep 14 of PosiCourse, PositoAI's free stock market course, explains the key ratios.
Suggested reading
How to Compare Two Companies · What Is the P/E Ratio? · How to Understand Company Debt · What are Dividends? · What is Fundamental Analysis?
Summary
A stock screener filters thousands of companies down to those meeting conditions you choose, such as P/E, ROE, debt, dividend yield or size. Each extra condition narrows the list quickly. Sensible limits, attention to industry differences and awareness of odd or missing figures make screens more useful, and every company on the final list still needs a closer look.