Online Information Review

Purpose – This work aims to check the validity of the hypotheses of the agency, signalling, political costs and proprietary costs theories in the disclosure of information online. More specifically, to determine the prevalence of the purposes alleged by those theories, we analyse the effect of industry concentration and other factors on an index of items of information disclosed on corporate web sites, in its entirety as well as its breakdown into information whose elaboration and disclosure is compulsory and information whose elaboration and disclosure is voluntary.

Design/methodology/approach – First, a content analysis of the quoted non-financial Spanish companies' web sites was carried out. To do this, three disclosure indexes were created and applied. Then three causal models were estimated by applying a linear regression, taking several factors into consideration.

Findings – The findings emphasise the relevance of the hypotheses of political costs theory as the main explanatory factor for voluntary disclosure of information on the internet by quoted Spanish firms. In particular, the hypothesis that the greater the firm's monopolistic power, the more visible the company is and the more political costs it faces. To reduce these costs, such companies have an interest in disclosing greater amounts of information.

Practical implications – The researchers have analysed only one year of data from one country, but this analysis is significant because the motives which lead a firm to disclose information can be very different depending on its geographic location, especially if the factors which determine disclosure practices are associated with the political costs that the companies face.

Originality/value – This is the first study to examine the effect of industrial concentration on the disclosure of information online.