Secret listing? Banned? Why Zillow isn’t showing you the whole market.

Much as Xerox has become the stand-in phrase for any copier machine or Kleenex has come to mean any tissue, Zillow is now the noun and the verb for house hunting. Because it garners so much attention — more than 2 billion visits to the real estate site for the first quarter of 2025 — people expect to see every house for sale there. But there are some exceptions.

The site, like others that aggregate home listings, gets feeds from multiple listing services, better known as MLSs, regional databases real estate agents use to share information about homes on the market. An MLS itself is only available to real estate professionals. There are some reasons home sellers might choose to keep an MLS out of the loop, though. We’ll get into those shortly.

In the spring, Zillow announced that any publicly marketed listings must appear on an MLS within one business day or the site will ban them, starting at the end of June. (This mirrors a National Association of Realtors rule about agents cooperating through MLSs and adds some enforcement from Zillow.) Redfin followed suit with the same policy.

Compass, a major brokerage, is now suing Zillow, calling the site a monopoly and characterizing this policy as an antitrust violation. The real estate firm has been pushing its own collection of so-called private exclusives, homes available only to Compass agents and buyers who sign up with them — at least at first. Other large brokers have also launched internal listing networks. Zillow’s policy would, in effect, ban these homes from ending up on the aggregator.

“This lawsuit is about protecting consumer choice,” Compass CEO Robert Reffkin said in a statement. “No one company should have the power to ban agents or listings simply because they don’t follow that company’s business model. That’s not competition. It’s coercion.” The company has been fighting against the NAR cooperation rule more broadly, too.

Zillow, which makes its money by charging real estate agents a referral fee for connecting them to motivated buyers and sellers, has also framed its policy as one that protects consumer choice. “Real estate works best in the open — not behind closed doors — and that’s what we, and most of the industry, are focused on preserving,” said Errol Samuelson, Zillow’s chief industry development officer. “The vast majority of agents and consumers want the same thing: maximum exposure. More visibility means more competition, stronger offers, and ultimately better outcomes for both buyers and sellers.”

Let’s get into why a listing may not appear on Zillow or other major aggregators and what it means for homebuyers or sellers.

What is an off-market listing?

Some ultra wealthy or extremely private people might prefer for their listings to remain out of the public eye. After all, Zillow and other aggregators display a comprehensive amount of information, often alongside photos, all of which remain available long after the home purchase.

An off-market listing “makes sense for people like Tom Brady,” said Bonnie Lai, an agent with RE/MAX in Boston. “Everyone will show up to an open house and want to see everything.”

Other instances when an off-market listing, also known as a pocket listing, might be a good idea could involve a home sold “as-is” because it may not look good in pictures or people who don’t want to be disturbed by a big sale process, said Gabrielle Witkin, an agent with Sotheby’s International Realty in Washington.

What you lose when you sell off-market is potential for more competition. Fewer eyeballs could mean fewer offers driving up the price.

And, of course, there’s a question of who knows about homes on offer off-market. Lai works with many first-time homebuyers. “If most of the stuff is off-market, then they would never get a shot to access all of them,” she said.

There will always be some off-market listings, but they are an outlier rather than the rule.

How the ‘Zillow ban’ will work

Zillow introduced its policy this spring that agents must list their for-sale homes on the site within one business day or otherwise face a permanent ban for the listing. At the end of last month, the company began contacting agents who seem to have violated this policy. On June 30, Zillow started block listings. “We expect only a small number of for-sale listings will be affected,” Samuelson said.

Many sellers want their homes on Zillow and other aggregators. “Sellers are often buyers at the same time, or have been,” Witkin said. “And so I think that they may be viewing Zillow as that’s how they look at homes. So what’s going to happen if buyers out there can’t see their home on Zillow?”

This blocking is what Compass is contesting with its lawsuit. Why aren’t brokerages always immediately listing homes on an MLS? Basically, real estate agents may “soft launch” a home sale. They circulate that the home is on the market in some circles without officially listing it with an MLS.

“It can help them test the market and test the price,” said Witkin, who briefly worked with Compass this year. “It doesn’t hurt a seller to privately market their home, even if it’s just one week before you plan to go on the market. … You can still go on the market, but it would be helpful to have the opinion from buyers who are actively looking.” They listen to feedback on price, staging and more. It’s a beta test of sorts before the big rollout because “once you’re publicly on Zillow, you’re everywhere.”

As soon as a listing hits an MLS, the countdown of “days on market” begins. The longer a home has been on the market, the less desirable it may appear. MLSs, and therefore Zillow and other aggregators, also keep track of any changes in price, which may also serve as red flags to prospective buyers.

Plus, Zillow’s listings include a “Zestimate,” an estimate of the home’s price that might be lower than the sale price. “It’s not super accurate, but we definitely have sellers and buyers that do kind of rely on that number,” said Lai, who often has to explain why those figures might be off by a large percentage.

If those homes do field a good offer before getting officially listed, they might never hit the public market. And, for brokerages who advertise their exclusive listings, that means they could get the benefit of a commission on both the buy and sell side.

Lai sees the fight between Compass and Zillow as two titans each fighting in their own self-interest. But she is concerned about the trend toward more private listings, which degrades the quality of MLSs and makes it harder for smaller brokers to compete. She anticipates that trend making it more difficult for the consumer, too. “People would need to use seven different agents to go find one house because … they will all have different access to different listings,” she said.

Witkin said she educates her clients about their options. “Ultimately, the choice is up to my sellers. Do you want to do a test phase and privately list first, or do you value your home being on Zillow?” she said. “At the end of the day, there’s no one size fits all.”