Abstract: An apparatus, system and method for completing advertising time slot transactions. A time slot exchange server receives an offer to sell a time slot along with time slot information relevant to making an buying decision with respect to the time slot. The time slot exchange server makes available time slot offer and marketing and valuation data to assist a buyer to identify and properly value a time slot that meets the buyer's requirements. The time slot exchange server receives time slot bids and transfers the ownership of a time slot from a seller to a buyer when a bid meets or exceeds the terms of the time slot's offer to sell. The time slot exchange server also ensures that a broadcaster has a correct copy of an advertisement to be shown in a time slot, and sends verification data to an advertiser indicating whether, when and how an advertisement intended to be shown in a time slot was actually seen.