Purchases of previously owned homes fell to a four-month low in October, as limited inventory and increasing mortgage rates stymied upward momentum in the housing market.

Sales of previously owned homes dropped 3.2 percent to a 5.12 million annual rate in October, the fewest since June, according to recent data from the National Association of Realtors (NAR). The partial federal shutdown in October may have delayed some closings, the group said. The September reading was unrevised at a 5.29 million-unit pace.

The median price of an existing property increased 12.8 percent in October from the year before to $199,500, today's figures showed.

The jump in property values reflects a changing in the "mix" of sales toward higher-end properties, NAR chief economist Lawrence Yun said at a press conference. A limited supply of houses priced at $100,000 or less led to a 16 percent drop in sales in that category over the past year, Yun said; in contrast, sales of homes costing $250,000 or more are up 20 to 30 percent over the same period.

"Clearly, the affordability conditions are worsening," Yun said, adding that sales will probably remain subdued through the first quarter of 2014. They will pick up thereafter, spurred by gains in employment, he said.

There were 2.13 million existing homes for sale at the end of October, down from 2.17 million the month prior, the report said. Inventory was up 0.9 percent compared with October 2012, and it would take 5 months to sell those houses at the current rate, compared with 4.9 months at the end of September.

Purchases of single-family homes decreased 4.1 percent to an annual rate of 4.49 million. Multifamily properties including condominiums sold at a pace of 630,000, an increase of 3.3 percent from the previous period. Existing-home sales, which are counted when a purchase contract closes, are rebounding from a 13-year low of 4.11 million in 2008. That's almost 3 million fewer than the record attained in 2005.