We are paid by the buyer's broker, who in turn shares a commission from the seller. When a seller uses a real estate agent to sell an apartment in New York City (and the vast majority of all apartments in New York City are sold by real estate agents), the seller agrees to pay the broker a predetermined commission. In addition, the broker agrees to 'co-broke' the apartment with all of the other firms in the city. This means that the broker representing the seller (also known as the listing broker) will contact all other brokers to see if there they have any buyers who may be interested in the apartment in question. If so, the two brokers (the listing broker and the buyer's broker) will share the commission. This is how most apartments in New York City are sold.