Sentence:  Private-equity nabobs bristle at being dubbed mere financiers....Much of their pleading is public-relations bluster. Clever financial ploys are what have made billionaires of the industry's veterans. “Operational improvement” in a portfolio company has often meant little more than promising colossal <WSD>bonuses</WSD> to sitting chief executives if they meet ambitious growth targets. That model is still prevalent today. 
Meaning of the word marked with <WSD> tags:  An extra sum given as a premium, e.g. to an employee or to a shareholder.