There has been much talk about this issue and concern. But if you look back over the years, the notion that any market purchases would have created a problem due to material good information thereafter has never really happened. In fact the only controversy followed their sale of stock following a run up. So while perhaps a theoretical concern, I'd have to conclude they don't buy stock becuase they get it for free through options and/or they outspend their income and can't afford to buy a meaningful amount.
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