The average homeowner in these 10 cities lost half of their equity in just a year, according to Forbes magazine.

Equity is the difference between what a home is worth and how much you owe on your mortgages.

Because homes are the biggest source of savings for most Americans, these families lost a huge chunk of their personal wealth in a very short time.

Most of them live in areas where soaring home prices required (or allowed) owners to take out huge mortgages until property values began to fall in 2007.

The cities that have lost the most home equity from June 2007 to June 2008 are:

Modesto, Calif. Down 68% to an average equity of $26,350.

Sacramento, Calif. Down 63% to an average equity of $53,438.

Lansing and East Lansing, Mich. Down 61% to an average equity of $16,810.

Riverside, Calif. Down 58% to an average equity of $79,431.

Port St. Lucie, Fla. Down 53% to an average equity of $59,390.

San Diego, Calif. Down 52% to an average equity of $107,559.

Vallejo, Calif. Down 52% to an average equity of $120,297.

Las Vegas, Nev. Down 51% to an average equity of $54,228.

Grand Rapids, Mich. Down 51% to an average equity of $22,951.

Stockton, Calif. Down 51% to an average equity of $87,657.

See how the median sales pricesfor single-family homes in your city has changed over the last year.