Globalisation has become extremely intense since the earlier seventies. Given that the world economy is getting dose to a single market, a more efficient outcome via globalisation can be expected. However, globalisation may also have negative effects. We illustrate our findings through a simple cobweb model where we analyse different shape and slope of the aggregate supply curve. We show that when globalisation is too intensive, it leads to more instability on markets because of a reduction of behavioural diversity. The economic literature indicates that this diversity can be necessary for market stability as well as for macro-economic stability. We demonstrate that as a result of globalisation, the goals or motivations of economic agents may become more uniform (more profit-oriented) and generate market instability.