This paper analyzes the use of an internet forum by employees of a retail chain in France to exchange information and discuss about a major corporate change. We show how the forum takes on core functions being neglected by the company and how it contributes to the appropriation of change. Through detailed analysis of the posts, we identity the professional logic at work and link it to corporate dynamics. This helps explaining, among others, the homogeneity of the topics discussed, which directly deal with change issues, and the defusing of a massive rejection of change. The method used to analyze the posts (combining human and partially automatic processing) and the criteria used to identify professional dynamics also have a broader academic interest.