Oligopoly behavior.
wNumber of sellers high.
wProducts heterogeneous.
wLarge differences in costs.
wOrders lumpy and infrequent.
wPrice information is secret.
wRole of trade associations.
w“Social structure” not conducive to collusion.
Elbert H. Gary (1846-1927), founder of U. S. Steel and convener of the  famous “Judge Gary dinners” at which Steel industry competitors set production quotas and collusive prices.   
Secret price cutting most likely when: