In 1929 when the US economy was in a state not unlike today two major brands took two very different paths in regards to ad spend. The paths that these brands took would influence the future of the brand up until this very day.
In 1929 the biggest cereal brand in America was Post Cereals. When the depression started Post decided to make heavy cuts to their ad budgets. On the other hand one of their competitors decided not to cut ad budget. That competitor was called Kelloggs (you might have heard of them). Kelloggs came out of the depression as the Number one cereal brand, a position they hold till this very day.
This highlights the importance of marketing, and keeping track of your competitors marketing activity, and that there will be some winners in these hard financial times.
