The number of single-family homes put under agreement in September was down 19 percent over the same time last year, while condominiums were down 27 percent, according to the Massachusetts Association of Realtors.

A total of 3,609 single-family homes were put under agreement last month, down from 4,473 last year. On a month-to-month basis, single-family homes put under agreement were down 12.3 percent from 4,117 homes in August.

The number of condos put under agreement in September fell to 1,267 units, from 1,725 units in 2009. On a month-to-month basis, condos put under agreement were down 11.7 percent, from 1,267 units in July.

This is the fifth straight month that year-over-year pending sales have gone down, MAR said.