Listings spread around the Web

The nation’s 900 multiple listing services, or M.L.S.’s, are loosening up restrictions on their listings. For years, they didn’t let Web sites display M.L.S. listings along with properties not represented by real estate agents, such as for-sale-by-owner homes and bank foreclosures. Now M.L.S. data is flowing more freely to sites like Zillow, Terabitz, ZipRealty and Redfin. In Massachusetts, the state’s M.L.S. Property Information Network recently agreed to feed data straight to Zillow, although it lists for-sale-by-owner homes and will soon add foreclosure listings. Many in the industry are fighting the changes, and some real estate sites, such as Trulia, fear that offering for-sale-by-owner listings would cause brokers to stop listing their properties.