[Update: Zillow modified strength of search to 1.2 million]

Zillow (Z), an online real estate marketplace, expanded its home-search experience by adding pre-market inventory for home shoppers. 

It said 1.2 million pre-foreclosure and foreclosed properties — part of the nation's shadow inventory — will now be viewable for no cost. Overall, the nation had 2.3 million homes sitting on the sidelines that were either seriously delinquent, in foreclosure and real-estate owned in July, CoreLogic said.

Zillow is showing the homes not yet listed for sale and can’t be found on Multiple Listing Service or any other real estate sites, the company said.

"This is another tremendous step forward in consumer empowerment. Zillow is taking information that was really only available to a select group – in this case, savvy investors –  and making it more easily available to interested home buyers," said Spencer Rascoff, Zillow's CEO. 

Until now, there was a vast portion of the housing inventory that was invisible to potential buyers. Typically, only skilled investors could find information on these houses.

Research has shown that 55% of home buyers have contemplated buying a foreclosed home but were unaware of where to find out more or were turned off by the complex transaction. Zillow hopes that buyers are able to connect with a real estate agent who work closely with foreclosures and can assist them in the process of buying a foreclosed home.

Agents must pay Zillow to get their ad placed next to properties in their local catchment areas.