What Fraction of Stock Option Grants to Top Executives Have Been Backdated or Manipulated?
估计1996-2005年间，13.6%的高管期权授予被回溯或操纵；其中非计划且平价授予的操纵比例达18.9%，2002年新规后降至10.0%。科技、小规模及高波动性公司操纵更频繁。
We estimate that 13.6% of all option grants to top executives during the period 1996–2005 were backdated or otherwise manipulated. Our study primarily focuses on grants that were unscheduled and at-the-money, of which we estimate that 18.9% were manipulated. The fraction is 23.0% before the new two-day filing requirement took effect on August 29, 2002, and 10.0% afterward. For the minority of grants that are not filed within the required two-day window, the fraction of manipulated grants remains as high as 19.9%. We further find a higher frequency of manipulation among tech firms, small firms, and firms with high stock price volatility. In addition, firms that use smaller (non-big-five) auditing firms are more likely to file their grants late. Finally, at the firm level, we estimate that 29.2% of firms manipulated grants to top executives at some point between 1996 and 2005.