One in 16 homes in the UK will have changed hands by the end of the year, with more than £500bn of residential property sold.
Savills said 56% of buyers have been those with cash or equity to spend, while those with mortgages made up just 44%.
Zoopla said the year had been the busiest for the housing market since 2007. Its figures show that buyer demand is 19% higher than the five-year average, while the supply of homes available to buy has dropped by 42%. The imbalance has pushed prices up by almost 7% over the year, to an average of £240,000.