1. A method of estimating a probability of re-sharing information, comprising: extracting keywords from a set of documents addressed to a user, said documents being published on social media; weighting the keywords from the set of documents according a metric for the user's interest in the keywords' respective source documents to create an interest model; receiving a new document having one or more keywords; determining a likelihood that the user will re-share the new document on social media using a processor, said likelihood being based on the interest model and the one or more keywords present in the new document, wherein the likelihood comprises a probability defined as: P ( u , m ) = a ⁡ ( t m ) ⁢ ( 1 - ∏ j ⁢ ⁢ ( 1 - q j ( u ) ⁢ f j ⁡ ( m ) ) ) where f j (m) is 1 if the keyword j appeared in a post m and is 0 otherwise, where q j (u) is a weighted value for the keyword j for the user u, and where α(t m ) is an activity function at time t m ; and automatically performing one of addressing a complaint in the new document, issuing a press release, or initiating an advertising campaign, using a processor, responsive to the new document based on the determined likelihood.