Trade logging: what it is, and where it goes wrong
Trade logging is the practice of recording details about trades you place—such as the planned entry/exit information, the actual execution, costs, and the notes you use to explain decisions—so you can review what happened later. It does not, by itself, create certainty. Mistakes usually come from misunderstanding what a log can show, mixing stable record-keeping mechanics with variable market or provider conditions, or using the log as if it guarantees future outcomes.
Common mistakes and what they can cause
1) Treating “what you planned” as “what you got”
A frequent mistake is logging planned prices as if they were the executed prices. In real execution, the fill can differ due to spread, slippage, partial fills, or delays. If you record only intentions, your later review may attribute results to decisions when the outcome may have been driven by execution differences.
Material consequence: your measured performance may reflect market microstructure and execution quality more than your process.
Neutral check: for each trade, separate “planned” fields from “actual” fields (execution time, execution price, and any realized costs).
2) Omitting costs and making hidden assumptions
Another error is failing to include or consistently record transaction costs (commissions, swap/financing where applicable, and other fees) and execution-related costs (effective spread). Even if you keep entry/exit correct, two trades with the same nominal price change can have different net results once costs are considered.
Material consequence: comparisons across trades, days, or strategies become inconsistent.
Neutral check: state the assumption behind any calculation in your log (for example: whether you used gross vs net figures, and what costs were included).
3) Making examples without specifying the calculation basis
People often copy a template and run quick numbers without documenting the basis. For example, calculating risk as “distance to stop” without clarifying whether you used pip value per lot, contract size, or account currency can lead to arithmetic that is not comparable later.
Material consequence: you may believe you are measuring risk consistently, when you are not.
Neutral check: for every worked calculation, note the units and conversion assumptions (pip value method, position size, and currency conversion rules if any).
4) Mixing process notes with outcome-only conclusions
A log can become biased when notes focus on the final result (“won so it was correct”) rather than the factors you actually observed when you made the decision. This turns the log into a story that confirms the outcome.
Material consequence: review becomes less useful for improving decision quality.
Neutral check: write decision notes in a way that can be checked later (e.g., what you believed at the time, what information you used, and what would have invalidated the thesis), without turning the log into a promise about future trades.
5) Overwriting, leaving fields blank, or changing definitions midstream
Logs become unreliable when you retroactively change earlier entries, rotate definitions (for example, redefining “setup quality”), or leave key fields empty. Consistency matters for any comparison.
Material consequence: trends you see may be artifacts of changing definitions, not changes in performance.
Neutral check: keep definitions stable and track edits; if you must change fields, record the change and be cautious interpreting older entries.
Limitations and risks to keep in mind
Trade logging is not real-time prediction. Market conditions, costs, execution quality, and even record formats can vary. Historical relationships do not automatically establish future results, and the same entries can lead to different outcomes under different liquidity and volatility regimes.
Material failure modes include:
- Recording only executed outcomes while omitting the decision context, making root-cause analysis impossible.
- Recording intentions only, which can hide the true impact of execution and costs.
- Overgeneralizing patterns from a small sample, even when the log looks “clean.”
Verification and next steps
You can verify the usefulness of a trade log using neutral checks:
- Confirm that each trade has consistent “planned vs actual” fields.
- Recalculate a small subset using the stated assumptions and compare to what your log reports.
- Check that costs are included the same way for all trades.
- Ensure definitions and measurement units did not change over time.