The stocks of traditional media companies, including Walt Disney, Viacom, AMC and Sony, hit the skids last week amid weak earnings reports.

Much of the problem is that consumers and advertisers are switching from old-school viewing platforms, such as cable and satellite TV viewing platforms to Internet platforms, either on a TV, computer, tablet or cell phone. Viewers are cutting the cord from their cable and satellite TV service.

The S&P 500 Media Industry Group Index has plunged 8 percent since Monday.

One game changer for the industry has been Netflix, which has 42 million viewers, and provides its own content on the Internet.

"Netflix has the rest of the industry well and truly spooked," business writer Dorothy Pomerantz writes on Forbes.com. "The service is driving the way people watch TV (and increasingly, movies) today and the traditional media companies now have to figure out how to stay relevant."

Some TV networks now offer themselves on the Internet outside the traditional bundle packages of cable and satellite service providers. Of course that generally means less money for the networks. They make their profit through advertising and subscriber fees.

But their fees go down outside bundled packages. And as viewers watch content in many different places, often bypassing ads, the networks' ad revenue suffers too.

To be sure, not everyone has turned bearish on media companies. The subscriber losses at Disney's ESPN division announced this week "generated an overhang over the sector and downward pressure on all media shares," Morningstar analyst Neil Macker writes on the research firm's web site.

"Given that these subscriber losses were well-known and relatively small, we believe that the sell-off was overdone and created a buying opportunity."

Disney CEO Bob Iger acknowledged Tuesday that there have been "some subscriber losses" for ESPN, but he said that Nielsen's estimate of 3.2 million subscribers lost in just over 12 months was too high.

As for Macker, he likes Disney and Time Warner, both of which are trading about 20 percent below his fair value estimates.

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