Two of the nation's largest real estate listing sites are at ends over "pocket listings."

Beginning in May, Zillow said it would ban “pocket” listings — homes marketed exclusively to a select group of buyers — from appearing on its website.

“If a listing is marketed directly to consumers without being listed on the MLS and made widely available where buyers search for homes, it will not be published on Zillow,” the company said on its website.

In response, Andy Florence, CEO of Costar Group, which owns Homes.com, sent an email to agent subscribers where he criticized Zillow’s policy, calling it a “power play of epic proportion.”

“This isn’t about protecting consumers. It’s about protecting Zillow’s ability to profit from your listings by selling your leads to competing agents,” Florence said.

Not too long ago, the National Association of Realtors came up with a policy known as the "Clear Cooperation Policy," or CCP. That regulates how listings need to be placed on the MLS, or Multiple Listing Service, for exposure to agents and real estate databases. Zillow is in support of this move, while Compass has argued in favor of pocket listings.

Cliff Freeman of the Cliff Freeman Group, brokered by eXp Realty, believes that the more eyeballs that are on a home that is for sale, the more likely someone will be able to "address the addressable market."

"You're not going to take a subset of people and just try and sell a home to those people," Freeman said. "You're going to show the home to the entire market in order to optimize the outcome for the sellers."

Zillow is by far the largest real estate market portal. Recently, they had unveiled a new rule threatening to permanently ban listings of homes from its website that had been marketed elsewhere as exclusive inventory. Their argument is if a home is going to be marketed somewhere then it should be marketed everywhere.

"Fragmented listing access - in which a home is available on one platform but not another, or shared with some agents but not others - creates frustration and distrust," the company said in its announcement.

Freeman said sellers should want their listing to be posted in as many places as possible and not be exclusive to one site. He also believes the real estate agent must put the client's interests first.

"There are some brokerages who are essentially trying to break this global market up so that they can have their own little space and have their secret listings," he said.

Michael Berry