A listing agreement is a contract between homeowners and brokers that legally establishes how a realtor will find a property buyer on the seller's behalf. If a cooperating broker is involved in the lease transaction, Owner shall pay a.Prior to being entered in the MLS all "Coming Soon" Listings must have a: 1. Valid fully executed listing agreement. 2. The most common listing agreement allows the broker to. A) guarantee the purchaser will accept. A real estate agent can function as a transaction brokerin which case he can work with both the buyer and the seller in the same transaction.