Title: Opinion Mining for Business Intelligence Applications Authors: Horacio Saggion - University of Sheffield Work on opinion mining has been fuelled by the development of evaluation programs such as the Text Retrieval Conference (TREC) 2006 track on blog mining for opinion retrieval or the National Institute of Informatics Test Collection for Information Retrieval (NTCIR) Workshop on Evaluation of Information Access Technologies and the new Text Analysis Conference (TAC) with a track on opinion summarization. Opinion mining consists of several different problems, such as determining whether each segment of text (sentence, paragraph, or section) is ``opinionated'' or not; identifying the opinion-holder (the person or organization who expresses the opinion); and determining how positive or negative each opinion is. For business intelligence, it is also useful to classify each opinion according to the aspect of the business or transaction described: e.g., product quality, ordering, or integrity. Opinion analysis helps to assess the limitations of particular products and then exploit this information in the development of improved products or services. It also helps enterprises understanding their customers as well as plan for future products and services. Given the abundance of reviews on the World Wide Web about companies, products, and services especially with the more recent proliferation of blogs and other Web 2.0 services, one application is to identify for a given entity its features and then identify what is being said about them (positive or negative statements), in order to compile summaries of opinions about particular entities or features. This information is then compiled in order to produce a textual summary together with statistics about what has been said. Opinion summaries are useful instruments in competitive intelligence for example, because they help assess the limitations of particular products and then exploit this information in the development of improved produces or services by the producer or its competitors. The work to be presented in the paper has been carried out in the context of the business intelligence Musing project, and in particular with respect to a target application whose goals is to compute and track the reputation of business entities. One of the core components of such application is a natural language processing application which identifies opinions in text about a given entity. The paper will describe experiments carried out for the identification of opinions on Web sources. We will describe in detail the problem, the data sources used, the linguistic processing applied to the data for the derivation of usefull document representations, the machine learning experiments carried out, and the results.