A stock scanner applies explicit filters to a large universe and returns candidates for review. It does not know whether a candidate fits a member’s circumstances, whether the next move will follow the historical pattern, or whether a displayed price can be executed.
Start With the Job
Define the setup and holding period before choosing filters. A breakout, pullback, mean-reversion, and opening-range review need different inputs. Mixing them into one undifferentiated score makes the result harder to interpret.
Useful Filter Categories
- Liquidity: price, share or dollar activity, spread, and other execution constraints.
- Structure: trend, range, moving-average relationship, or distance from a defined level.
- Participation: volume compared with the symbol’s own history and session segment.
- Context: market posture, sector behavior, verified catalyst, and scheduled events.
- Risk feasibility: whether a defensible invalidation can fit the loss budget.
Each filter removes part of the universe; none proves that a remaining symbol is a good trade.
Demand an Output Contract
A useful result should expose the symbol, scanner source, as-of time, setup label, relevant levels, and enough score detail to understand why it appeared. Evidence should distinguish supported historical samples from insufficient, stale, or unavailable states.
Check Freshness and Failure Modes
Scanner data can be delayed, incomplete, revised, or temporarily unavailable. A candidate can also fail because of a gap, spread change, news update, false break, or a market move that occurred after the scan. Verify the current chart and source data before using the result in a plan.
Backtests Are Not Live Guarantees
Historical evidence depends on universe selection, timestamps, fill assumptions, slippage, survivorship, and the exact rule definition. Keep sample size, expectancy, and evidence status visible when available. Do not convert a high score or favorable sample into certainty about one candidate.
Use the Scanner as the Start of Review
After a name surfaces, confirm liquidity, chart structure, catalyst, market and sector context, invalidation, and size. Record why a candidate was rejected. Non-triggers and failed candidates belong in the research set alongside successful examples.
Where MAC Terminal Fits
MAC Terminal has no scanner that ranks the whole market. Its starting list is narrower: every theme more than a point ahead of SPY over 10 sessions and still ahead over the last 3, and the names in each theme’s basket, listed alphabetically with their average daily range and their distance from the 20-day high. No name on that list is picked or ranked, and the description has not been tested as a predictor. From there the member sets entry and stop on the chart, or takes the opening-range plan during the session, and Guardrails calculates the size. A name on that list describes price; it is not an instruction.
Educational only. Scanner results can be wrong, stale, illiquid, or unprofitable. Validate the data, definitions, costs, and risk controls before using any scanner in live decisions.