Existing home sales in the United States declined in September after a month of stagnation in August, the U.S. National Association of Realtors (NAR) announced on Friday.

Total existing-home sales, which are completed transactions that include single-family homes, townhouses, condominiums and co-ops, fell 3.4 percent from August to a seasonally adjusted rate of 5.15 million in September, according to NAR data.

"This is the lowest existing home sales level since November 2015," said Lawrence Yun, NAR's chief economist. He pointed out that rising interest rates have led to a decline in sales across all regions of the country.

The median existing-home price for all housing types in September was 258,100 U.S. dollars, up 4.2 percent from September 2017. September's price increase marks the 79th straight month of year-over-year gains.

NAR said that total housing inventory at the end of September decreased from 1.91 million in August to 1.88 million existing homes available for sale, and is up from 1.86 million a year ago.

Unsold inventory is at a 4.4-month supply at the current sales pace, up from 4.3 last month and 4.2 months a year ago.

"There is a clear shift in the market with another month of rising inventory on a year over year basis, though seasonal factors are leading to a third straight month of declining inventory," said Yun. "Homes will take a bit longer to sell compared to the super-heated fast pace seen earlier this year."

The NAR is America's largest trade association, representing 1.3 million members involved in all aspects of the residential and commercial real estate industries.