There is provided a computer-implemented method of performing sentiment analysis. An exemplary method comprises identifying one or more sentences in a microblog. The microblog comprises an entity. The method further includes identifying one or more opinion words in the sentences based on an opinion lexicon. Additionally, the method includes determining, for each of the sentences, an opinion value for the entity. The opinion value is determined based on an opinion value for each of the opinion words in an opinion lexicon.