Existing-home sales unexpectedly dropped in July as cancellations of pending contracts continued to depress buying activity.

The National Association of Realtors said sales fell 3.5 percent month over month to an annual rate of 4.67 million units. June's sales were upwardly revised at a 4.84 million-unit rate.

Economists polled by Reuters had expected sales to rise 3.8 percent to a 4.90 million-unit pace. Compared to July 2010, sales were 21 percent higher.

(Reporting by Margaret Chadbourn; Editing by Kenneth Barry)