The number of zombie homes - vacant properties abandoned by owners during the foreclosure process - rose in 30 U.S. states and the District of Columbia in the second quarter of this year from the previous quarter, real estate data analytics company ATTOM said in a May 29 statement.

Zombie homes, which can fall into disrepair and negatively impact the value of other properties in the neighborhood, are a sign of distress in the housing market and the broader economy.