This paper reexamines the popular assumption that real estate commissi
ons are fixed over time. It shows how the competitively determined com
mission rate responds to changes in the housing market and broker cost
conditions. One testable implication is that competition promotes cou
nter-cyclical changes in the commission rate. The empirical analysis o
f commission rate determinants using data covering an entire urban hou
sing market through its downturn and expansion phases reveals the coun
ter-cyclical movement in commission rates predicted by the competitive
model. (C) 1997 Academic Press