On embodiment accesses a set of information comprising one or more elements of information relating to a subject matter, wherein the one or more elements of information have been shared among one or more users of a social-networking system; for each element of information, determines a rate of sharing of the element of information among the one or more users and identifies one or more first users who cause the rate of sharing of the element of information to increase; and identifies one or more influencers associated with the subject matter from the one or more first users identified for each element of information.