Final answer:
The contract in question is a Net Listing, where the real estate agent's commission is any amount received over a set net price for the seller. It can create a conflict of interest and is not legal in all areas.
Step-by-step explanation:
The listing contract which provides that the agent may retain as compensation for their services all sums received over and above a net price to the owner is known as a Net Listing. This type of agreement is controversial and is illegal in some states because it can create a conflict of interest; the agent might prioritize their own profit over the seller's best interest. In a net listing, the seller sets a minimum amount they want to net from the sale. Any amount above this set value that the property sells for is the agent's commission. For example, if a seller wants to net $300,000 and the property sells for $350,000, the agent's commission would be $50,000.
This is different from other types of listing agreements like the Exclusive Right to Sell Agreement or an Exclusive Agency Agreement, where the commission is a predetermined percentage of the selling price, or an Open Listing, which allows multiple agents to market the property with only the selling agent earning a commission.