An online social network is provided. A sentiment is determined for each of a plurality of users of an online social network (OSN) in relation to a first product. A category is determined for each of the plurality of users based, at least in part, on the sentiment of each of the plurality of users, respectively. A group including a first user and a second user of the plurality of users is generated based, at least in part, on the category of each of the first user and the second user and a relationship within the OSN between the first user and the second user. An advertisement is presented to the first user. An indication is presented to the first user that the advertisement is also presented to the second user.