As Bloomberg notes, the decline, which was broad-based across all four regions, shows that higher mortgage rates, rising prices and a shortage of affordable homes continue to squeeze buyers. Existing-home sales in August matched the lowest in more than two years, while revisions to new-home sales showed a slower market than thought, according to previously released figures.

AR continues to blame low inventory and affordability

"Pending home sales continued a slow drip downward," Lawrence Yun, NAR's chief economist, said in a statement.

"The greatest decline occurred in the West region where prices have shot up significantly, which clearly indicates that affordability is hindering buyers and those affordability issues come from lack of inventory, particularly in moderate price points."