The objective of this study is to test the effects of market share and industrial conditions on the performance of companies, basing our evaluations on their stock value and resources. The basic hypotheses are: i) an increase in market share that is not supported by changes in the fundamental resources of the firm does not generate value (performance); and ii) industrial conditions influence a firm’s performance. The methodology uses a recursive model taken from Financial Theory to estimate the annual changes in the firms’ value, and the effects that industrial conditions have on their performance. The method also employs other statistical techniques to demonstrate the relationship between the annual fluctuations in a firm’s value and the annual changes in its market share. The novel aspect of this approach is that it allows us to detect the interactions, one by one, that occur among the different firms of a given sector. Based on the results obtained from the application of this model to nine companies in the Spanish construction sector, we demonstrate that an in- Efectos cuota de mercado e industria sobre los resultados 187 dustry effect does indeed exist. However, we also find that there is an insufficient statisfical basis to demonstrate that increases in market share which are not supported by a change in firms’ comparative resources do not generate excessive profits.

Keywords: performance, market share, firms’ resources, industry effect.
JEL classification: L11.