Zillow has been undervaluing homes in certain black and Latino neighborhoods, according to a coalition of community activist groups.

The National Community Reinvestment Coalition has complained to the Federal Trade Commission that Zillow's web site has misrepresented home values, placing residents in low-income neighborhoods "more at risk for discriminatory and predatory lending practices," the New York Times reports. NCRC urged the FTC to start an investigation and permanently restrain Zillow from providing home valuations. Zillow says the charges have no merit.

NCRC claims that its review of the site found that Zillow's home value estimations were within 10 percent of appraised value less than one-third of the time - and that in low-income neighborhoods the inaccuracy was much more frequent. It would not release details of its findings.

Zillow estimates homes' valuations based on data it collects from public sources on a home's characteristics, tax assessments and recent sales. The validity of its valuations have consistently been questioned, but the site remains popular, with 3.5 million visitors in September. It claims to be the fifth most-trafficked real estate website in the United States.