Prop firm spread markups: recalculating expectancy

[FXS London Scalper]

Some prop firms add a markup to spreads or charge higher commission than a typical retail raw account. For scalpers, even a small markup affects expectancy significantly.

Example:
- Your strategy on a raw account: 0.2 pip spread + 0.7 pip commission = 0.9 pips cost per trade.
- Prop firm: 0.4 pip spread + 0.7 pip commission = 1.1 pips.

With a 4-pip target and 4-pip stop:
- Raw: break-even win rate = (4 + 0.9) / 8 = 61.25%.
- Prop: (4 + 1.1) / 8 = 63.75%.

If your strategy wins 62%, it's profitable on raw and losing on prop.

What to do:
- Measure the actual spread on the prop account during your trading hours.
- Recalculate break-even win rate with prop costs.
- Consider wider targets to make costs a smaller share.

Have you compared your costs on prop vs personal accounts?