Ad spending: growing market share

If I yell louder but you yell even louder, the audience will hear you. So I shouldn't expect to be heard if I also start yelling louder, unless you become quieter. That, in essence, is the key to the relative share of voice effect in advertising. In most markets, consumer goods markets are in a state of equilibrium, where advertising expenditures are relatively stable and changes in market share are small. To gain ground in market share, a competitor has to launch a huge ad campaign for a sustained period that outspends the biggest rival by at least double.