In marketing, who is the challenger?

In marketing , who is the challenger?

The challenger has market share below that of the market leader but can be a potential threat to the market leader as they have good chances of replacing the market leader’s position in the future. Eg. A Montessori school which has been set up next to a high school which is the no.1 ranked institution in a particular area,could be a challenger as in the near future , it may expand and convert into a high school and even further build a university campus in its area thereby having more number of students that its counterpart.