What is a stock screener?

Why screening beats scrolling

NSE and BSE together list several thousand companies; NYSE and Nasdaq add thousands more. Reading them one by one is not a strategy. A screener inverts the problem: you describe the company you want, and the market hands you the shortlist.

The output of a screen is never a buy list. It is a research queue — usually 10 to 40 names — that is small enough to actually read annual reports for.

The filters that do most of the work

Market capitalisation sets the risk band. Large caps move slower and are better covered; small caps swing harder and are where mispricing usually hides.

Valuation filters (P/E, P/B, EV/EBITDA) tell you what the market is already paying for the earnings. Treat EV/EBITDA as usable only when EBITDA and enterprise value support a positive multiple. Quality filters (return on equity, debt-to-equity, interest coverage) tell you whether those earnings are durable.

Growth filters (revenue and profit CAGR over three to five years) separate a cheap compounder from a cheap melting ice cube. Liquidity filters (average traded volume) stop you from finding a great business you cannot exit.

Building your first screen

Start deliberately loose: market cap above a floor you are comfortable with, debt-to-equity under 1, positive five-year profit growth, and return on equity above 15%. That single combination removes the vast majority of the market.

Then tighten one filter at a time and watch the count. If a change wipes out the whole list, the rule was an opinion rather than a filter.

Save the screen and re-run it monthly. Names entering and leaving the list are a signal in themselves.

Common mistakes

Over-filtering to five perfect names is curve fitting. Screening on a single ratio — cheapest P/E in the market — reliably surfaces companies that are cheap for a reason.

Screens are backward looking. Every number in them describes what already happened; your judgement supplies the forward view.

Frequently asked questions

Is a stock screener free?

DeepScreen's screener is free to use across NSE, BSE, NYSE, Nasdaq and LSE, with paid plans for advanced tooling and saved portfolios.

How many stocks should a good screen return?

Aim for 10 to 40 names. Fewer suggests the filters are over-fitted; many hundreds means you have not filtered at all.

Can a screener predict which stocks will go up?

No. A screener sorts historical and current fundamentals. It narrows where you spend research time; it does not forecast prices.