Sales of existing homes in the United States had a large increase in December, likely as a result of delayed transactions from previous months.

The National Association of Realtors says the pace of annual existing home sales stood at a seasonally adjusted total of 5.46 million, a 14.7 percent increase from November and 7.7 percent increase from December 2014. The tabulation includes single-family houses, townhouses, condominiums, and co-ops.

The jump in sales comes one month after the pace of existing home sales declined sharply in November, falling 22.5 percent from the previous month and 3.8 percent from the previous year. The National Association of Realtors said this drop was likely influenced by new "Know Before You Owe" closing documents introduced in October, which it says have resulted in longer closing periods.

"While the carryover of November's delayed transactions into December contributed greatly to the sharp increase, the overall pace taken together indicates sales these last two months maintained the healthy level of activity seen in most of 2015," said Lawrence Yun, chief economist at the National Association of Realtors. "Additionally, the prospect of higher mortgage rates in coming months and warm November and December weather allowed more homes to close before the end of the year."

Sales for 2015 closed out at 5.26 million existing homes. This total was the largest since 2006, when 6.48 million existing homes were sold during the year.

The number of existing homes available for purchase fell 12.3 percent from November to 1.79 million. This total was also down 3.8 percent from December 2014.

Median prices for existing homes continued to increase, marking the 46th consecutive month of rising values. Existing homes sold for a median price of $224,100 in December, up 7.6 percent from the median price of $208,200 in December 2014.

Increasing prices and shrinking inventory continue to present challenges for first-time homebuyers. These buyers made up 32 percent of existing home sales in December, the largest share since August; it was also up from 30 percent in November and 29 percent in December 2014. However, a separate survey from the National Association of Realtors found that the share of first-time buyers in 2015 was at its lowest point in almost 30 years.

"First-time buyers were for the most part held back again in 2015 by rising rents and home prices, competition from vacation and investment buyers, and supply shortages," said Yun. "While these headwinds show little signs of abating, the cumulative effect of strong job growth in recent years and young renters' overwhelming interest to own a home should lead to a modest uptick in first-time buyer activity in 2016."

Yun said he expects to see some growth in existing home sales in 2016, but not as much as the activity that led to a 7 percent increase in sales in 2015. He said some factors that will likely lead to a slowdown include increasing mortgage rates and less demand in oil-producing metropolitan areas.

Mortgage rates are expected to begin climbing in 2016 as a result of the Federal Reserve's increase in short-term interest rates. Data from Freddie Mac indicates that the average commitment rate for a 30-year conventional fixed rate mortgage was below 4 percent in December for the fifth month in a row, but also rose slightly from 3.94 percent in November to 3.96 percent in December. This rate was also above the average rate of 3.85 percent for 2015.

Single-family homes sold at a seasonally adjusted annual rate of 4.82 million in December, up from 4.15 million in November and 4.5 million in December 2014. These homes sold for a median price of $226,000, a year-over-year increase of 8 percent.

Sales of existing condominiums and co-ops were up 4.9 percent from November and 12.3 percent from December, to a seasonally adjusted pace of 640,000. The median price for a condominium or co-op sold in December was $209,900, up 4.9 percent compared to the previous year.

Existing homes on the market in December were usually sold in 58 days, an increase of four days from November but a decrease of eight days from December 2014. Non-distressed homes sold the fastest, with an average time on the market of 57 days. Foreclosures typically spent 68 days on the market before a sale, while short sales were on the market for an average of 66 days. Thirty-two percent of existing homes sold in December were on the market for less than a month.

Foreclosures made up 6 percent of existing home sales in December, while short sales accounted for 2 percent. The combined 8 percent share of distressed properties was down from 9 percent in November and 11 percent in December 2014.

Foreclosed properties typically sold for 16 percent below market value in December, up from 15 percent in November. The average discount for short sales remained at 15 percent, unchanged from the previous month.

Twenty-four percent of existing home sales in December were all-cash purchases, up 3 percentage points from November but down 2 percentage points from the previous year. Individual investors—64 percent of whom paid cash for a property—accounted for 15 percent of existing home sales in December. This share was down from 16 percent in the previous month and 17 percent in the previous year.

The Northeast region had the strongest increase in existing home sales from the previous year, increasing 11.9 percent from December 2014 and 8.7 percent from November to a rate of 750,000. Homes in this region sold for a median price of $255,700, a 5.3 percent increase from the previous year.

Sales in the West had the most significant increase from the previous month. The sales rate in this region was 1.22 million, up 23.2 percent from November and 8.9 percent from December 2014. An existing home in this region sold for a median price of $321,100, up 8.2 percent from December 2014.

Existing home sales in the South had an annual rate of 2.27 million, up 14.6 percent from the previous month and 4.6 percent from the previous year. The typical home in this region sold for $196,100, a year-over-year increase of 6.8 percent.

In the Midwest, the annual rate for existing home sales was 1.22 million in December. This pace was up 10.9 percent from November and 9.9 percent from December 2014. The median price increased 7.5 percent from the previous year to $171,000.