The number of lots offered last month fell by 18%, compared with October 2014.
The drop was partly due to five major auction houses delaying their October sales to November, according to Essential Information Group, which compiled the data.
However, EIG managing director David Sandeman said: “It is still apparent that the market has slowed since the heights of 2014, when the volume of lots offered and sold at auction was reaching record-breaking numbers.”
The October success rate was up by 1.2% on 2014, but sales fell by 4.6% to £517.5m.
The slowdown was greatest in the residential sector, where the number of lots offered dropped by 20% to 2,465, compared with the same month last year, and sales were down by 13.8%.
The commercial sector saw an 11.9% decrease in lots offered last month, but quarterly sales were up by 9.3%.
