WASHINGTON (AP) — Home prices fell in January for a fifth straight month in most major U.S. cities, as modest sales increases have yet to boost prices.

The Standard & Poor's/Case-Shiller home-price index shows prices dropped in January from December in 16 of 19 cities tracked.

The steepest declines were in San Francisco, Atlanta and Portland. Prices increased in Miami, Phoenix and Washington. Price information for Charlotte was delayed and therefore not included in the report.

The declines partly reflect typical offseason sales. The month-over-month data are not adjusted for seasonal factors.

Still, prices fell in 17 of the 20 cities in January compared to the same month in 2011. That suggests the housing market remains weak, despite the best winter for sales in five years.