Standard 1% risk calculation for a $10,000 account
By limiting risk to $100 (1% of account), this trader can absorb a consecutive losing streak of 10 trades and still have 90% of their capital intact. This longevity gives a positive expectancy system time to play out and demonstrate its edge over a statistically meaningful sample.
Many traders skip this calculation and instead buy round lots (100 shares, 1 full contract) based on gut feel. This leads to inconsistent risk, emotional decision-making during losses, and eventually account blowups.