Existing-home sales stumbled for the fourth time in five months as strained supply levels continue to subdue overall activity, according to the National Association of Realtors. Sales gains in the Northeast and Midwest were outpaced by declines in the South and West.

Total existing-home sales, which are completed transactions that include single-family homes, townhomes, condominiums and co-ops, retreated 1.7 percent to a seasonally adjusted annual rate of 5.35 million in August from 5.44 million in July. Last month's sales pace is 0.2 percent above last August, and is the lowest since then.