Otherwise, why make it complicated? They'd just offer $X. The reason that this is done is because investment banks tend to have larger revenue swings than many

Otherwise, why make it complicated? They'd just offer $X. The reason that this is done is because investment banks tend to have larger revenue swings than many other businesses. Due to this, they want to be able to more easily adjust their costs (of which people are a huge %) relatively easily. It's much easier to adjust bonuses up and down than base salaries.