Before the opinion was that because a large number of firms have prodcuts that are tied to the succes of the allegedly monopolized product, desktop operating systems of microsoft, they would prospor if actions are taken to make operating systems cost less, function better or provide a more convenient platform for popular products.

Study looks at stock market evidence. Result: Government action against Microsfot appears to inflict capital losses on the computer sector as a whole.
On the other hand (symmetric): Retreats in antitrust enforcement offer symmetric confirmation that withdrawals form policy enforcement have been accompanied by positive shareholder returns throughout the comptuer sector.

Why important:
1.Policy intervention: Actions cost lot of money to microsoft and government (taxpayers). Gains fail to be in evidence.
2. Reults suggest antitrust policy has lowered returns to investments in the computer sector and discouraged capital inflows. Policy risks increases the risk in Cost of Capital for whole industry
3: risk of 'fanciful reasoning'