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Why a refused order should explain itself

A rejection that says "order failed" trains traders to retry blindly. Naming the limit, the projected value and the ceiling changes behaviour in one interaction.

28 May 2026777 Raptor2 min readriskexecutiondesign

Here are two ways to refuse the same order.

Example
Order rejected.
Example
Order rejected: EURUSD exposure would reach 0.75 lots
against a per-instrument limit of 0.50.

The first teaches a trader to click again. The second teaches them the limit.

Silent rejections are an operational cost

A rejection with no reason produces a support ticket, a phone call to the desk, or — most often — a retry with a slightly different size until something goes through. That last one is the worst outcome, because the trader has now learned the boundary by brute force and has no idea which of the several checks they were hitting.

Every refused order in Raptor names three things:

  1. Which check refused it — exposure, concentration, margin, instrument scope, permission, or the automation mandate.
  2. The projected value the order would have produced.
  3. The ceiling it would have crossed.

That is enough for the trader to correct the order themselves, immediately, without asking anyone.

The order of the checks is part of the design

Pre-trade validation runs in a fixed order, and the first failure stops the order:

Example
Instrument tradeable            PASS
Account permission              PASS
Size within instrument bounds   PASS
Margin available                PASS
Aggregate exposure limit        PASS
Concentration limit             REFUSE

Fixed order matters because it makes the message deterministic. The same order in the same account state always produces the same explanation, which is what makes the explanation trustworthy — and what makes an incident reproducible three weeks later.

The same rule applies to automation

An order EMIL proposes goes through the identical gate and produces the identical explanation, written to the intelligence log:

Example
09:41:02  REFUSE   Order rejected: would breach concentration
                   limit on correlated positions.

This is the part most people skim past, and it is the most informative line in the log. Anyone can build a system that reports its trades. A system that reports what it was stopped from doing is telling you where its boundaries actually are.

What we deliberately do not do

We do not silently reduce an order to fit. A ticket for 0.75 lots that becomes 0.50 without comment is a system making a decision on the trader's behalf and not telling them. If size needs to change, the trader changes it.

Related: the capital architecture · what EMIL does when armed

Trading leveraged products carries a high level of risk to capital. Technology can improve analysis and controls; it cannot remove market risk.

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