A screener lets you ask a database “show me profitable companies growing revenue 15% yearly with modest debt and low price-to-earnings” and returns names in two seconds. Sounds like it should produce winners reliably, yet most people who use one still buy badly within the month, because they read the results list as recommendations rather than as questions worth investigating.
What a screener is and isn’t
It’s a filter over reported data, nothing more. Every number has already been published for weeks and priced by professionals with better tools. So the moment you find something “cheap,” assume someone else noticed; either they disagreed, or information isn’t in the numbers, or there’s a problem the ratio doesn’t capture such as declining revenue that happened just now.
Cheap means cheap relative to some measure, never automatically good. A stock can trade at eight times earnings while its profits quietly evaporate, cheap on yesterday’s numbers, expensive looking forward. Ratios are backward-facing instruments, which is precisely what makes them useful and dangerous simultaneously. See Price-to-Earnings Ratio: The Most Popular Metric for what specifically goes into that denominator.
Filters worth understanding rather than copying
Earnings growth, revenue and profit rising across several consecutive years. One exceptional year flatters every screen ever built. Look for consistency; three straight years beats one spike. Beware companies that turned marginally profitable from deep losses, producing spectacular percentage gains off tiny bases.
Debt levels. Total debt divided by equity, plus whether operating cash flow plausibly covers interest payments. Rising rates reprice floating obligations almost immediately while refinancing older fixed debt gradually, so debt load becomes newly relevant after long easy-money stretches. If that framing is unfamiliar start with Reading the Balance Sheet: Assets, Liabilities, Equity before running this filter.
Return on equity: profit generated per dollar of shareholder capital. Sustained high ROE often indicates genuine competitive advantage; spikes frequently indicate accounting effects or excessive leverage inflating a ratio whose denominator shrank via buybacks or losses. High ROE demands an explanation, and if you can’t construct a plausible one, the number isn’t telling you anything usable yet. See Moats: Buffett’s Competitive Advantage Concept for what defensible economics look like when real.
Free cash flow versus reported net income, divergence between headline profit and actual cash generated suggests aggressive recognition or working-capital games. The gap is among the earliest warning signs available without reading footnotes line-by-line, covered properly in Free Cash Flow: The Money That Matters and adjacent earnings-quality material.
Don’t set ten filters hunting perfection. You’ll retrieve funds, foreign listings with different disclosure regimes, mid-crisis survivors where one catastrophe distorted everything, and statistical anomalies meaningless going forward. Start with four criteria maximum and read the rejected results too, since learning why borderline cases got excluded teaches more quickly than examining your small winner list and feeling clever.
The site’s own screeners
Several strategies come pre-built here, each encoding one investor’s checklist. Their value isn’t in returning stocks to purchase but in showing how differently reasonable people weight the same inputs: Graham’s emphasis on asset-based safety margins and conservative balance sheets, Lynch prioritizing growth-at-reasonable-price and understandable businesses, Buffett concentrating on durable advantage and return on invested capital, Ichan paying patient attention to unloved situations with catalysts. Browse all seven and notice their results barely overlap despite describing the identical market. Disagreement about what counts as quality is legitimate, permanent and invisible from any single strategy’s output. Each links directly to its source methodology; treat these as teaching tools rather than shopping lists.
Try this today, twenty minutes
Open any free screener and apply exactly three filters: five consecutive years of revenue growth, positive free cash flow every year, total debt below one year of revenue. Note how many companies survive, usually far fewer than expected. Then take the top result and search its revenue for the past decade rather than the filtered window, checking visually whether growth looks continuous or was one lucky period everyone still trades off.
Do the opposite next: relax filters until hundreds of matches appear and pick through the bottom rows asking why the market prices those firms so pessimistically. Answers range from dying industries to litigation to fraud investigations to genuinely misunderstood franchises, and knowing which category you’re dealing with requires reading actual filings. If ratios stop making sense along the way, go back through Income Statement: Revenue, Expenses, Profits first, and when the exercise starts producing more questions than answers, keep going; that means it’s working.
Educational content, not financial advice. Screeners filter historical data and identify candidates for research, never guarantees of future performance. Screeners help you decide what to study, not what to buy, and money committed on a screen’s say-so can be lost like any other investment.