U.S. home price increases leveled off in December, reflecting a weak sales environment and a small number of homes for sale.

The Standard & Poor's/Case-Shiller 20-city home price index increased 4.5 percent in December compared with 12 months earlier. That is up from 4.3 percent in November and the same as October's annual increase.

Fewer homes are on the market, pushing up prices and keeping many houses out of reach for would-be buyers. Prices are rising faster than most Americans' wages, slowing sales even as hiring strengthens, consumer confidence grows and mortgages stay low.

The Case-Shiller index covers roughly half of U.S. homes. The index measures prices compared with those in January 2000 and creates a three-month moving average. The December figures are the latest available.