Understanding Position Sizing Beyond 'X% of Account'

Many new traders are taught to risk 'X% of their account' per trade. While conceptually sound, this often oversimplifies to a fixed dollar amount without considering the actual volatility or potential movement of the instrument being traded. For instance, risking the same fixed dollar amount on a tight range-bound $NZDCAD at 0.81659 as on a more volatile stock like $SAP at $160 can lead to vastly different probabilities of hitting stop-loss and, ultimately, inconsistent risk management.