Not just insider trading... If the information is still not known, e.g. a really big contract (not publicly announced yet) that will definitely cause the share price to decrease/increase, that friend will also be breaching his own company's secrecy policies. If for whatever reason the "news" leaks out and somebody buys $50M or subtantially causing the price to increase/decrease by a big %, and somehow ring alarm bells with vested parties (e.g. another potential contract awardee) you may even be sued for spreading confidential information, or if the person is a government official, charge for breach of Official Secrets Act. Dont be greedy lah... Integrity... That friend may lose his job too, you dont want to be guilty to cause it.