We study trading patterns of corporate insiders in their own personal portfolios. To do so, we identify accounts of corporate insiders in a large dataset provided by a retail discount broker. We show that insiders overweight firms from their own industry. Furthermore, insiders earn substantial abnormal returns only on stocks from their industry, especially obscure stocks (small, low analyst coverage, high volatility). In a battery of tests, we find no evidence that corporate insiders use private information and conclude that insiders have an informational advantage in trading stocks from their own industry over outsiders to the industry.
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