Our paper describes how competitive action repertoire concept and the external regulatory environment influence the performance of a firm in the regulated telecommunications sector. Based on panel data of 103 firms across Europe that provide fixed broadband Internet to end customers during the time period of 3 years, results indicate that aggressiveness and the complexity of an offer have a positive relationship with market share growth. Contrary to widespread views, we find that the most aggressive firms in the market in fact lose market share on a year-on-year basis. Our results suggest that complexity and aggressiveness have a positive relationship with changes in market share gains and that the effects hold for non-regulated firms, but not for regulated ones.