Rewriting the rules after one bad trade
Posted: Sat Oct 31, 2026 7:19 pm
A single large loss creates a strong urge to change something. A new filter, a tighter stop, or an extra condition is added to prevent that exact scenario from recurring. The rule feels responsible.
Over time, the strategy accumulates patches, each addressing a one-off event. The rules become complicated and overfit to the past, with little effect on the future.
A disciplined approach asks whether the loss was within the expected distribution. If a loss of that size should occur once in a thousand trades, it requires no change. If it occurs more often than predicted, the model of risk is wrong, and that is a different problem.
Before changing a rule, test it on a larger dataset. Does the new filter improve the overall results or only avoid that one trade? The cost of the filter, in missed good trades, needs counting.
Keep a change log with the reason and the evidence. Review it periodically to see which changes helped.
Stability of rules is a strength.
How many rule changes in the last year were backed by statistical evidence rather than by a single event?
Over time, the strategy accumulates patches, each addressing a one-off event. The rules become complicated and overfit to the past, with little effect on the future.
A disciplined approach asks whether the loss was within the expected distribution. If a loss of that size should occur once in a thousand trades, it requires no change. If it occurs more often than predicted, the model of risk is wrong, and that is a different problem.
Before changing a rule, test it on a larger dataset. Does the new filter improve the overall results or only avoid that one trade? The cost of the filter, in missed good trades, needs counting.
Keep a change log with the reason and the evidence. Review it periodically to see which changes helped.
Stability of rules is a strength.
How many rule changes in the last year were backed by statistical evidence rather than by a single event?