Laughter, as component of social interaction, has attracted interest within conversational analysis. While laughter can be expressed in different contexts, voluntary or involuntary, and diverse in function and degree of functionality, it is not random. We study timing of laughter during conversation in relation to topic changes: whether recurrent patterns in laughter distribution with respect to topic changes exist; whether laughter is a reliable topic termination cue. We explore a corpus of multiparty spontaneous chat approaching the problem in two steps: at a coarse-grained level, we analyze the temporal distribution of laughter with respect to topic boundaries; then, at a finer level we will analyze the differences in distribution of shared and solo laughter. The two main points of our work can be summarized by these two questions: I) how laughter is distributed around topic boundaries? II) is there evidence of the "shared laughter-topic termination" relation and of "solo laughter-topic continuation" relation?