Insider traders appear to be pretty careful in choosing their accomplices. Of the known pairs of people who provide and act upon private information (“tipper and tippee”), 64% met before college, and 16% met in college or graduate school. Another 23% are family relations — more siblings and parents than aunts and uncles, despite the added capital that the latter might have provided. Tips are also commonly shared among people with ethnically similar surnames: Of 24 tips coming from people with Celtic surnames, for example, 14 went to individuals who also had Celtic surnames.

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