Prices of U.S. single-family homes fell for a second straight month in July, the Federal Housing Finance Agency (FHFA) said on Wednesday.

The FHFA's house price index dropped by a seasonally adjusted 0.5 per cent after declining by a revised 1.2 per cent in June, which was previously reported as a 0.3-per-cent fall.

The regulator's index is calculated by using purchase prices of houses financed with mortgages sold to or guaranteed by mortgage finance companies Fannie Mae or Freddie Mac.