A stock screener is a tool that filters stocks based on criteria you set. Instead of manually checking thousands of companies one by one, a screener does the work in seconds and shows you only the stocks that match what you're looking for.
Why Use a Screener?
There are roughly 6,000 publicly traded stocks in the US alone. Nobody has time to research all of them. A screener narrows the field so you can focus your limited research time on the best candidates.
Think of it like apartment hunting. You wouldn't visit every apartment in a city. You'd filter by price range, neighborhood, and number of bedrooms first. A stock screener does the same thing for investments.
Common Screening Criteria
Sector
Different sectors behave differently depending on economic conditions. Technology companies have tended to attract higher valuations when interest rates are low. Energy and utilities are usually described as more defensive, which is why they come up in conversations about inflation and uncertainty. None of that is a forecast. It is the vocabulary people use when they group companies this way.
Filtering by sector lets you focus on industries you understand or want exposure to.
Market Capitalization
Market cap tells you the size of a company:
- Mega cap (over $200 billion): Companies like Apple, Microsoft, and Amazon. Very stable, well-covered by analysts, lower risk but often slower growth.
- Large cap (over $10B, up to $200B): Established companies with solid track records. Good balance of stability and growth potential.
- Mid cap (over $2B, up to $10B): Companies that are still growing. More volatile than large caps but with more room to expand.
- Small cap (up to $2B): Younger or niche companies. Higher risk, potentially higher reward, less analyst coverage. Our screener's Small bucket covers any company whose displayed cap reads $2.0B or less.
Large and mega caps are the easiest place to start reading. There is more information published about them, more analyst coverage, and a longer public record to check a story against.
Price and Daily Change
Not every column is a filter. On ConvictionStocks price and daily change are sort options rather than filters: you narrow the list by sector, market cap and trend, then order whatever survives by market cap, price, daily change or name.
Sorting is worth doing on purpose. A list ordered by daily change puts the day's biggest movers at the top, and a big move is a reason to go and read something, not a finding on its own.
Trend
A moving average is the average price over a set window, such as the last 50 or 200 trading days. It smooths out daily noise to show the underlying direction. The ConvictionStocks screener calls this filter Trend, and it keeps stocks trading above or below their 50-day or 200-day average, which is a common way to separate names that have been rising from names that have pulled back. The averages behind it are exponential, which means recent days count for more than older ones.
A moving average describes the trend. It does not predict it, and the screener says exactly that underneath the control.
How to Screen Effectively
Start Broad, Then Narrow
Don't set too many filters at once. Start with one or two criteria (like sector and market cap) and see what comes up. If the list is too long, add another filter. If it's too short, loosen your criteria.
Don't Over-Optimize
A common mistake is setting filters so tight that you only get two or three results. This doesn't mean you've found the "best" stocks. It means you've probably excluded good candidates with criteria that are too rigid.
Use the Screener as Step One
The screener gives you a shortlist, not a portfolio. After filtering, click through to individual stock pages and actually read the research. Check the company description, look at the key metrics, review analyst consensus if available.
The screening phase should take 5 minutes. The research phase is where you spend real time.
Screen Regularly
Markets change. A stock that didn't pass your filters last month might look different now after an earnings report or market shift. Check your screener weekly or bi-weekly to see what has changed.
Common Screening Strategies
Large and Stable
Filter for mega and large cap stocks in any sector. This gives you established companies that are well covered by analysts and easier to research. Good for building a diversified watchlist.
Sector Deep Dive
Pick one sector you understand well and filter just within that space. If you work in healthcare, screening healthcare stocks might surface companies you already have insight into.
Above the Long-Term Average
Set Trend to above the 200-day average to see names that have been rising over a long window. Pair it with a sector or market cap filter to narrow the list. Sitting above an average is a fact about the price, not a verdict on the company.
Behind Its Own Recent History
Set Trend to below the 50-day average to see names whose price has fallen behind where it has recently been. That is where a company in real trouble turns up, and it is also where an ordinary company turns up after an ordinary bad month. The filter cannot tell you which one you are looking at, so the reading is the work.
What a Screener Cannot Do
A screener filters data. It doesn't predict the future. No combination of filters will guarantee a stock goes up. The screener removes noise and helps you focus, but the final investment decision always requires judgment and additional research.
Also, screeners only work with quantitative data. They can't capture things like management quality, competitive moats, or industry disruption risks. Those require reading, thinking, and forming your own view.
Try It
Head to the ConvictionStocks screener and start with a simple filter: a sector you understand, large cap. Browse the results, click on a few companies that interest you, and start building your research habit.
The goal isn't to find the perfect stock in one session. It's to develop a repeatable process for finding good candidates and researching them thoroughly.
This content is for informational purposes only and does not constitute financial advice.