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 <WSD>improvement</WSD>” in a portfolio company has often meant little more than promising colossal bonuses to sitting chief executives if they meet ambitious growth targets. That model is still prevalent today. 
Meaning of the word marked with <WSD> tags:  The act of improving; advancement or growth; a bettering