Well, say your company is going to buy another company. You know about it, and buy shares of tbe other company ahead of the public anouncement. You are essenti

Well, say your company is going to buy another company. You know about it, and buy shares of tbe other company ahead of the public anouncement. You are essentially stealing from your own company, since your purchase of shares will drive up price and result in your employer paying more than they otherwise would have. Though for the record, I think insider trading should be legal, or at least should be a civil instead of a criminal matter. The purpose of financial markets is decentralized price discovery and preventing the trading of certain types of non-public information is totally counterproductive in that regard.