Home prices decreased 0.3 percent nationwide on a seasonally adjusted basis from July to August, according to the Federal Housing Finance Agency’s (FHFA) monthly House Price Index.  The FHFA’s index is calculated using purchase prices of houses owned or guaranteed by Fannie Mae or Freddie Mac.  For the 12 months ending in August, U.S. home prices decreased 3.6 percent. The U.S. index is 10.7 percent below its April 2007 peak.