So you have inside information? LMFAO! I hope you don't plan to trade this stock now. Inside Information Definition: A non-public fact regarding the plans or condition of a publicly traded company that could provide a financial advantage when used to buy or sell shares of the company's stock. Insider information is typically gained by someone who is working within or close to a listed company. If a person uses insider information to place trades, he or she can be found guilty of insider trading. Insider trading is illegal when the material information has not been made public and has been traded on. This is because the information gives those having this knowledge an unfair advantage.