Updated: 2026-02-20
In trading, Commission is a per-trade fee charged by a broker or exchange for executing your order. This glossary entry explains why commission matters, how traders use it, and how to track it with evidence instead of vibes.
Quick definition
Commission: a per-trade fee charged by a broker or exchange for executing your order.
Commission is a per-trade fee charged by a broker or exchange for executing your order. The practical version is: can you define it as a field you can log and audit later?
Most trading terms become confusing when they are used as vibes instead of variables. Your goal is a definition that helps you decide size, stop, entry timing, or whether to skip the trade.
Traders sometimes confuse Commission with maker-taker fees. Treat them as separate variables in your journal so your reviews stay honest.
Commissions are small per trade but large per year if you trade frequently. If your edge is thin, commissions can turn a positive expectancy strategy into a slow bleed.
If Commission never changes your decision, it is just jargon. The term earns its place when it improves your process consistency under real market pressure.
A useful mental model: plan first (risk and invalidation), execute second (order type and fills), review last (tags and metrics).
Use it to make one decision pre-trade. Example decisions: where the stop goes, whether to take partials, how to scale size, or whether conditions are too thin to trade.
Write the rule in one sentence, then run it consistently for a week. Consistency matters because it creates comparable data for review.
If the rule fails, adjust slowly. Do not rewrite the whole system after one bad session.
Log commissions per fill and per session. Review fees as a percent of gross PnL and as a percent of notional traded. Track changes when you switch order types or venues.
Use tags so you can slice results by regime and behavior state. The same term behaves differently when volatility changes or when you are fatigued.
Your review question should be binary: did this variable improve outcomes or reduce rule breaks? If not, simplify.
If your average trade makes $12 gross but you pay $4 in commissions and spread/slippage, the strategy's net expectancy is much lower than it looks in a chart review.
The point of an example is not to predict price. It is to show what you would log before the trade and what you would audit after the trade.
Ignoring commissions in backtests and then being surprised when live results underperform.
The fastest way to improve commission is to remove one failure mode at a time. If you try to fix everything, you will fix nothing.
Commission matters most when volatility is high and the book is thin. That's where small execution errors compound into expectancy drag.
Before you trade, decide what matters more: price control (limits) or fill certainty (markets/stops). Then trade the choice consistently for one week so your data is comparable.
If you change order types every time you feel stressed, your metrics will lie to you.
Commission is a per-trade fee charged by a broker or exchange for executing your order. In practice, it matters when it changes a concrete decision like size, stop placement, or whether you skip a trade.
They are related but not identical. In your journal, track Commission as its own variable and treat maker-taker fees as a separate context factor so you can audit each cleanly.
Log commissions per fill and per session. Review fees as a percent of gross PnL and as a percent of notional traded. Track changes when you switch order types or venues.
Ignoring commissions in backtests and then being surprised when live results underperform.
See plans and run one weekly review loop with Tiltless: edges, leaks, and enforceable next actions.
