This dissertation deals with the impact of speculative behaviour on output patterns of the real

economy. The impact may be twofold. Speculative behaviour occurs due to positive developments at

the real economy and optimistic outlooks. Also, speculative behaviour may occur at other markets, like

the stock market. We address both, a spill-over effect and the build up of speculation due to economic

activity. Therefore, we implement realistic behaviour in an evolutionary framework and use emerging

heterogeneity for the impact assessment. Inspired by the dotcom-bubble we focus on technological

advancement as possible factor of growing optimism.

In the first part of this thesis we introduce feedback from stock prices into a model of economic growth

determined by financing constraints. We focus on three known feedback channels: stock market

information for the assessment of creditworthiness, stock market value as determinant in determining

bankruptcy of a firm and performance based compensation of the firm management.

The second part introduces financing constraints into an evolutionary framework and tackles determinants

of credit supply for their impact on the occurrence of innovation. Those determinants are

market based and also behavioural in nature.

The third part provides a more detailed bank behaviour and two industrial sectors competing for credit.

Therefore, the third part is a refinement of the second one.