Existing-home sales increased in August and reached the highest level in six-and-a-half years, while the median price shows nine consecutive months of double-digit year-over-year increases, according to the National Association of Realtors®.

Total existing-home sales, which are completed transactions that include single-family homes, townhomes, condominiums and co-ops, rose 1.7 percent to a seasonally adjusted annual rate of 5.48 million in August from 5.39 million in July, and are 13.2 percent higher than the 4.84 million-unit level in August 2012.

Sales are at the highest pace since February 2007, when they hit 5.79 million, and have remained above year-ago levels for the past 26 months.

The market may be experiencing a temporary peak. Rising mortgage interest rates pushed more buyers to close deals, but monthly sales are likely to be uneven in the months ahead from several market frictions. Tight inventory is limiting choices in many areas, higher mortgage interest rates mean affordability isn’t as favorable as it was, and restrictive mortgage lending standards are keeping some otherwise qualified buyers from completing a purchase.

Total housing inventory at the end of August increased 0.4 percent to 2.25 million existing homes available for sale, which represents a 4.9-month supply at the current sales pace, down from a 5.0-month supply in July. Unsold inventory is 6.3 percent below a year ago, when there was a 6.0-month supply. Limited inventory in some areas means multiple bidding remains a factor; 17 percent of all homes sold above the asking price in August, although 63 percent sold below list price.

Data from realtor.com, NAR’s listing site, shows large declines in inventory from a year ago in Naples, Fla., down 23.5 percent; the Detroit area, down 23.3 percent; and the greater Boston area, down 20.7 percent.

According to Freddie Mac, the national average commitment rate for a 30-year, conventional, fixed-rate mortgage rose to 4.46 percent in August from 4.37 percent in July, and is the highest since July 2011 when it was 4.55 percent; the rate was 3.60 percent in August 2012.

The national median existing-home price for all housing types was $212,100 in August, up 14.7 percent from August 2012. This is the strongest year-over-year price gain since October 2005 when the median rose 16.6 percent, and marks 18 consecutive months of year-over-year price increases.

Distressed homes5 – foreclosures and short sales – accounted for 12 percent of August sales, down from 15 percent in July, and is the lowest share since monthly tracking began in October 2008; they were 23 percent in August 2012. Ongoing declines in the share of distressed sales are responsible for some of the growth in median price.

Eight percent of August sales were foreclosures, and 4 percent were short sales. Foreclosures sold for an average discount of 16 percent below market value in August, while short sales were discounted 12 percent.

Rising home values will encourage more people to sell. As the equity position of most homeowners continues to improve, some who have been on the sidelines will list their home for sale. Most of those owners also will be buying another home, but higher levels of new home construction going into 2014, combined with some reduction in demand from less favorable affordability conditions, will help to moderate price growth to more sustainable levels.

The median time on market for all homes was 43 days in August, little changed from 42 days in July, but is much faster than the 70 days on market in August 2012. Short sales were on the market for a median of 98 days, while foreclosures typically sold in 52, days and non-distressed homes took 41 days. Forty-three percent of homes sold in August were on the market for less than a month.

First-time buyers accounted for 28 percent of purchases in August, down from 29 percent in July and 31 percent in August 2012.

All-cash sales comprised 32 percent of transactions in August, up from 31 percent in July and 27 percent in August 2012. Individual investors, who account for many cash sales, purchased 17 percent of homes in August, compared with 16 percent in July and 18 percent in August 2012. Last month, three out of four investors paid cash.

Single-family home sales rose 1.7 percent to a seasonally adjusted annual rate of 4.84 million in August from 4.76 million in July, and are 12.8 percent above the 4.29 million-unit pace in August 2012. The median existing single-family home price was $212,200 in August, which is 14.4 percent higher than a year ago.

Existing condominium and co-op sales rose 1.6 percent to an annual rate of 640,000 units in August from 630,000 in July, and are 16.4 percent above the 550,000-unit level a year ago. The median existing condo price was $211,700 in August, up 17.7 percent from August 2012.