A well-diversified portfolio can reduce the effects of firm-specific or industry-specific events – such as strikes, technological advances, and entry and exit of competitors – to almost zero. Risk that can be diversified away is known as unsystematic risk or diversifiable risk. Information that has negative implications for one firm may contain good news for another firm. In a well-diversified portfolio of firms from different industries, the effects of good news for one firm may effectively cancel out bad news for another firm. The overall impact of such news on the portfolio’s returns should approach zero.