To study illegal insider trading, I collect a sample of accounting irregularities from 1997 to 2006 related to problems
with revenue recognition, cost or expense and restructuring, assets or inventory. The sample includes only cases of
aggressive accounting or fraud that are more likely to be intentional and which lead to a higher drop in price when
publicly disclosed (Hennes et al., 2008). This selection procedure provides a powerful setting to examine the research
question because it emphasizes the factors that are hypothesized to affect illegal insider trading.