This paper considers the incentives of oligopolistic firms to diversif
y into technologically related markets when there are diseconomies of
scope. There is a rent extraction incentive for firms to adopt flexibl
e technologies which enable them to enter technologically related mark
ets, thereby increasing competition. However, this strategic motive le
ads to inefficiency in production owing to diseconomies of scope. This
paper shows that the welfare gain arising from increased competition
is offset by the inefficiency in production, which may lead to lower w
elfare than in the case or pure monopoly. This is a counter-example to
the contention that the diversification increases social welfare.