Previously, companies such as AOL Time Warner and Comcast were prevented from owning TV networks reaching more than 35% of homes in the US.
The decision made at the US Appeals Court in Washington, follows challenges in court by Viacom and News Corporation-owned Fox.
AOL Time Warner and Comcast are now said to be interested in NBC.
Microsoft, a major investor in Comcast and which has already spent millions on its MSNBC joint venture with NBC, is also said to be interested in buying the network.
According to analysts, there is likely to be a rush to buy up independent TV networks.
Mike Kupinski, media analyst at AG Edwards, said: "There will be a number of attractive targets, if they decide to sell right away."
Likely targets include Hearst-Argyle, which owns 27 stations; Sinclair, which owns 62 stations; and Belo Corp, which owns 17 stations.
The court said that it believed the 35% rule is difficult to justify in today's economic landscape, although there is likely to be some pressure from TV station owners and consumer groups who want the cap to stay in place.
Regulators have always had difficulty defending the rule. The court said the rules could be rewritten and the ban reinstated.
This can only happen if the Federal Communications Commission comes up with a satisfactory justification. Michael Powell, head of the FCC, has openly opposed the rule in the past.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .
.jpg)
.jpg)