An important issue in corporate strategy is to explain persistent diff
erences in conduct and performance among close competitors within an i
ndustry. While IO economists generally seek technology and market-base
d explanations, firm theorists and business policy scholars rather loo
k for historical and organizational reasons, The paper first summarize
s recent findings along these two approaches. It then studies sources
of persistent differences between two firms competing a la Cournot on
two identical markets. in this context both types of explanations are
found to matter, We show that the firms' respective capabilities (i.e.
the parameters that determine their cost of producing the two goods)
would diverge only if some difference in the firms' respective initial
capabilities exists or there is an appropriate combination of organiz
ational inertia (the cost for updating current capabilities) and marke
t conditions.