A stock screen narrows a large market into candidates for deeper work. It does not replace company research. Useful filters reflect the decision horizon and combine business quality, financial trend, valuation, liquidity and risk instead of depending on a single attractive number.
Define the purpose of the screen
A liquid intraday universe, a multi-session momentum list and a long-term quality shortlist need different filters. State the intended use before selecting metrics.
Combine complementary evidence
Revenue growth without cash flow, high returns with excessive leverage, or a low valuation during structural decline can mislead. Use a small group of measures that test different parts of the business.
- Revenue and profit trend
- Cash conversion
- Debt and return ratios
- Valuation context
Add market behaviour and liquidity
Price trend, relative strength, volume and spread help identify whether a security can be traded at the intended size. A fundamentally interesting company may still have poor execution quality.
Investigate every shortlisted company
Read current filings, results, material announcements and risks. Screening data can be stale, restated or distorted by one-off items, so the shortlist is the beginning of research.
Make the screen reproducible
Write the data source, date, universe and exact rule for each filter. Reproducibility prevents thresholds from being changed after seeing which familiar companies pass and makes later performance review meaningful.
Handle missing and negative values explicitly. A screen that silently removes companies with unavailable data can introduce a bias that is not visible in the final shortlist.
- Defined stock universe
- Data date and source
- Exact thresholds
- Missing-data rule
Perform a red-flag review after screening
For every candidate, read recent filings and examine auditor notes, pledging where relevant, related-party transactions, dilution, contingent liabilities and unusual working-capital changes. A numerical screen cannot interpret every governance or accounting risk.
Document why the company remains on the list and what evidence would remove it. The shortlist should evolve when new information appears, not only at a fixed rebalance date.
- Latest exchange filings
- Cash-flow quality
- Governance and dilution
- Removal condition