Shares of Microsoft rose more than 2 per cent on Wall Street last night after a US appeals court overturned a lower-court order that would have split the software giant in two.
The rulingsent rival stocks tumbling.
Microsoft shares rose $1.57 to $72.71 on the Nasdaq, where it was among the most actively traded stocks for the day, despite a halt in trade that lasted more than three hours.
Shares of the software giant's rivals reacted quickly to news the appeals panel threw out a finding by District Court Judge Thomas Penfield Jackson that Microsoft had tried to monopolize the market for Internet browsers.
AOL Time Warner, a maker of alternative computer operating software, and RealNetworks, the top maker of Internet audio and video software, dropped.
AOL dropped 60 cents, or more than 1.1 per cent, to $52.08.
Talks to include AOL's Internet service in a new Windows operating system broke down earlier this month, highlighting the bitter rivalry between the two companies.
"Basically everything that is positive for Microsoft is negative for RealNetworks in our view," said Mr David Bench, an analyst with Arnhold & S. Bleichroeder in New York.
But investors said that yesterday's decision and its impact may not be long-lasting.
"The decision is obviously having a positive effect on some related companies but I think it's short lived," said Mr Richard Weiss, chief investment officer at City National Investments.
"Who is to say the issue does not go back the other way - I would guess this is not the final answer." He added.