Screener attach

Also seen as: In and Out screeners, entry screener / exit screener, Qualify and Reject, Attach to In / Attach to Out

What do the two screener pools do?

The qualifying pool decides who is considered, and the rejecting pool decides who is thrown out — the app states each rule where the pool is: "Instruments must match an In screener to be considered." and "Instruments matching any Out screener are excluded."

Within a pool, membership is any, not all: the pool header reads "Match any" with the count of screeners in it, so an instrument that matches one qualifying screener is a candidate even if it fails the others, and an instrument that matches one rejecting screener is out even if it fails the others. Filters inside a single screener still combine with AND — see matches.

The two pools are only available together in Compose; the other asset-selection modes carry a single screener with no rejecting pool.

How do the qualifying and rejecting pools combine?

The candidate set is the union of what the qualifying screeners match, minus the union of what the rejecting screeners match:

$$S = \left( \bigcup_{i=1}^{n} Q_i \right) \setminus \left( \bigcup_{j=1}^{m} R_j \right)$$

where: $S$ is the set of instruments the strategy may hold at that rebalance; $Q_i$ is the set of instruments in the working scope that match the $i$-th qualifying screener; $R_j$ is the set that match the $j$-th rejecting screener; $n$ and $m$ are how many screeners sit in each pool; the working scope is the basket if it has instruments in it, and each qualifying screener's own universe otherwise; and when $n = 0$ there is no qualifying screener, so the candidates are the basket itself — with no basket either, the strategy has nothing to choose from and does not run.

Union (∪) is why "Match any" behaves the way it does inside a pool, and set difference (∖) is why one rejecting match is enough to remove an instrument no matter how many qualifying screeners liked it.

Two cases work differently in the engine than the formula suggests, and Fincanva raises a strategy alert to review for each. The same screener in both pools: a title that passes both is sold and bought back in the same rebalance, and the entry wins, unless a reinvest delay of at least 1 month holds it out. A rejecting pool over a basket with no qualifying screener: the engine sells what matches it and buys the same instrument back in the same rebalance, because the candidates are always the basket and no wait applies there — so the rejecting pool changes nothing.

Which titles does an entry screener put into the positions?

The positions are filled from the qualifying screeners' result in its order, and the order is decided in two steps.

1. The cap. When more titles pass than six times Max positions, the engine keeps only the most traded of them — the highest average traded volume — and orders them from the most traded down. The cap applies to the union of all the qualifying screeners, not to each one.
2. Your ordering row. A «Highest by…» or «Lowest by…» row keeps the first N titles of its own order, so it is how you decide which titles are preferred. Without one, the order is the cap's by traded volume, or — under the cap — an internal order of the index, which is not a merit.

So an ordering row decides the positions only when its last row keeps no more than six times Max positions: a row keeping more is cut back to the most traded before the positions are filled, and the positions go to the most liquid titles instead of the top of your ranking. Two alerts to review on the Asset selection card say where you stand: "No rule decides which names enter" when a qualifying screener has no ordering row, and "The engine does not keep the top of your ranking" when the last ordering row keeps more than the cap. When the Risk-On method is Ranking-based, the positions are filled from that method's own ranking of the candidates instead, and the two alerts stay silent.

With two or more qualifying screeners a title enters by passing any one of them, and the grey note "Passing any one of the screeners is enough to enter" says so: "A title enters if it passes at least one of the screeners, not all of them; to ask for both conditions, put them in the same screener."

What does it look like in practice?

A strategy's basket holds ten tickers, so that basket is the working scope:

AAPL · MSFT · NVDA · TSLA · JNJ · PFE · KO · WMT · XOM · GE

Two screeners sit in the qualifying pool and one in the rejecting pool. Suppose at this rebalance they match:

The qualifying union $Q_1 \cup Q_2$ is nine tickers — everything except GE, which matched neither, so it is never a candidate. Subtracting $R_1$ removes TSLA (a candidate via $Q_2$) and XOM (a candidate via $Q_1$), leaving seven:

AAPL · MSFT · NVDA · JNJ · PFE · KO · WMT

Those seven are what the strategy may hold at this rebalance. A Max positions cap applies on top: with the cap at 5, the strategy holds five of the seven rather than all of them. At the next rebalance the same three screeners are re-evaluated and the seven can be a different seven.

Does editing the saved screener change strategies that already use it?

No — attaching copies the screener's filters into the strategy at that moment, so a later edit to the saved screener in your library does not reach strategies that already have it attached. Each attachment is its own copy: you edit that copy's filters from inside the strategy, and the change affects only that strategy, never your library screener or another strategy that attached the same one. This is the same copy-on-use rule that governs Duplicate and Copy to Mine.

Fincanva does remember which library screener an attachment came from, but only to support one manual, one-directional action: Update source screener pushes the strategy's copy back onto the saved screener, overwriting its filters and universe. Nothing pushes the other way. When the attachment has no library origin — one inserted empty, or one whose original was deleted — the option is unavailable and reads "No source screener tracked — use Save as new instead".

How does Fincanva handle it?

• Attaching a screener to a strategy is not included on the Free plan. Free attaches none — a screener still runs on its own there — while Starter attaches 1, Advanced 2, and Ultimate and Professional 8. See what each plan includes.
• On Free, what needs a screener stays visible and marked. On the Asset selection card Screen and Compose keep their place, each with the plan's bars after its name — hovering them reads "Available from Starter" — and choosing one opens it as a switched-off preview: you see the surface with the starter screener filled in, but nothing in it can be changed and nothing is saved. Pressing the bars, or the key you are already previewing, opens the plan dialog — "Strategies with screeners are available from Starter" — and choosing Basket brings back what the strategy holds. The Basket's Filters are hidden on Free, unless the strategy already holds a screener. A strategy that holds one anyway — made on a paid plan, or copied — is kept intact, but its backtest is refused before you press it; see plan compliance.
• An attached screener is shown by name, and can be opened and edited without detaching it.
• Adding a second screener to a pool widens that pool, because a pool matches on any of its screeners — it does not tighten it the way adding a filter to one screener does.
• A rejecting screener over a basket with no qualifying screener changes nothing, because what it sells is bought straight back; Fincanva flags it as the alert to review "The exit screener changes nothing" rather than blocking it. With no basket and no qualifying screener the strategy has nothing to choose from, which blocks the run — see strategy alerts.
• A strategy on the screener path needs at least one attached screener before it can be saved and run: "Add at least 1 screener."
• The full step-by-step is in Attaching a screener to a strategy.