Higher-priced houses are taking a greater share of foreclosure activity, with houses priced in the top tier accounting for nearly one-third of all foreclosures in July 2009, according to new data from Zillow.com. "Top-tier" homes in terms of local values accounted for 30% of foreclosures in the month. Houses in the bottom third and middle third of values took an equal share -- 35% each -- of foreclosures in July, while the highest tier of values claimed the rest. Compared to 2006, top-tier homes now make up nearly twice the proportion of foreclosures, according to Zillow.com. At the height of the real estate bubble, properties in the lower one-third of home values made up 55% of all foreclosures, while homes in the medium range accounted for 29%. The top one-third represented only 16% of foreclosures, according to the data. Zillow defines the tiers based on the ratio of the current house value and the current level of the Zillow Home Value Index for the property’s county. The bottom tier bears a ratio in the 33rd percentile, middle-tier homes have a ratio between the 33rd and the 66th percentile, and top-tier homes take a ratio greater than the 66th percentile. The combination of heightened delinquency rates in Prime, Alt-A and Option adjustable-rate mortgages (ARMs), along with declining cure rates of borrowers improving in delinquency status, causes more foreclosures for borrowers outside the subprime mortgage market, according to Zillow analysts. Data from Amherst Securities showed a strong link between increased negative equity and the decreased probability of improving the delinquency status. At the end of Q209, Zillow estimated 23% of single-family homes are underwater on their mortgages. Because of this analysts expect cure rates to remain low. Write to Jon Prior.