Experts have opined for decades on the reasons behind the spectacular failure rates of strategy execution. In 2016, it was estimated that 67% of well-formulated strategies failed due to poor execution. There are many explanations for this abysmal failure rate, but a 10-year longitudinal study on executive leadership conducted by my firm showed one clear reason. A full 61% of executives told us they were not prepared for the strategic challenges they faced upon being appointed to senior leadership roles. It’s no surprise, then, that 50%–60% of executives fail within the first 18 months of being promoted or hired.