What real trading costs did to the agents' scores
11 November 2026 · a study on MonsterDesk's own paper account and its own tests
- Question
- The test each agent sits charged a small flat cost per trade. Is that what trading really costs us?
- What we did
- Measured every fill the desk has made against the price the agent decided on, market by market, and charged each market its own figure in the test: about 0.7% a side for small coins and 0.025% for stocks. A stop that fires in a fast market is charged more, as it is in real life.
- What it showed
- Scores fell hard. One stock agent went from 3.70 to -3.27 and another from 3.43 to -1.14. After that learn, 16 of the 18 agents were on the bench. The rule sets that held up were the ones that trade less often, on longer bars.
- What changed
- The test now charges the costs we measure, and re-measures them at every learn. An agent that only looked good because trading was nearly free in its test stays on the bench until it finds rules that survive real costs.
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