U.S. home values are poised to drop by more than $1.7 trillion this year amid rising foreclosures and the expiration of homebuyer tax credits, said Zillow Inc., a closely held provider of home price data.

This year’s estimated decline, more than the $1.05 trillion drop in 2009, brings the loss since the June 2006 home-price peak to $9 trillion, the Seattle-based company said today in a statement.