Home sellers who didn’t use a multiple listing service (MLS) collectively “left $1 billion on the table” over the past two years via lower closing prices, according to Zillow.

These homes off the MLS typically sold for $4,975 less than those listed on it in 2023 and 2024, a median loss of 1.5% nationwide, the study showed.

Off-MLS sales lowered the closing price in 44 out of the 46 states included in its study, Zillow reported. Sellers in 33 states experienced median losses exceeding 1%, and sellers in 10 states saw losses greater than 2%.

The greatest median loss was in California, where sellers not using MLS saw an average price reduction of $30,075, or 3.7%. That was followed by New York (-3.7%, or $13,749) and Massachusetts (-3.4%, or $20,171), Zillow said.

The study also found that homes in all price tiers typically sold for less when off the MLS, but lower-priced homes were most severely impacted.

Zillow analyzed 10 million transactions, with 2.7 million meeting criteria for comparing homes that sold on the MLS with privately listed sales. Some 97% of transactions were for homes included in the MLS listing, while “pocket listings,” sales that were marketed privately and seemingly only submitted to the MLS once a purchase contract was in place, accounted for 2%.