The Time Warner Cable logo is displayed on the back of a van in New York. TV companies’ shares sank this week as fears of cable subscribers’ cutting the cord spooked investors. (Joshua Lott/Reuters)

Media companies were slammed on Wall Street this week as investors grew increasingly fearful that even industry giants would be swamped by the rising tide of cord-cutting consumers and the ebb of traditional television viewing.

Whether their profits were rising or falling, and whether their earnings were better than expected or worse, some of the biggest names in entertainment saw their stocks plummet. This week, shares of CBS fell 6 percent, Disney dropped 9 percent, Discovery and 21st Century Fox each fell 11 percent, and Viacom tumbled 20 percent.

The broad sell-off of TV and entertainment stocks signals growing concern among investors that although major entertainment companies are still turning profits and in some cases reporting growing sales, they face increasingly stiff head winds from viewers who skip through advertisements or have dropped their cable subscriptions.

The cracks in the cable business showed Friday as Cablevision Systems, a large service provider around New York City, said it lost more than 130,000 cable subscribers in the most recent quarter compared with the same period last year, a drop of nearly 5 percent. Late last week, Time Warner Cable reported a 2.2 percent decline in subscribers. (Both companies’ overall revenue has been offset by growing Internet subscriptions.)

“I think that what the market, what investors are saying is that they are going to move to the sidelines and invest in other groups and figure out how media plays out,” said Laura Martin, who covers the media industry for the investment banking firm Needham & Co.

Cable subscriptions have slumped in recent years as watching TV online has become easier via services such as Hulu. And streaming platforms such as Amazon.com and Netflix have expanded their reach by making their own hit shows, including “House of Cards” and “Orange Is the New Black.” (Amazon chief executive Jeffrey P. Bezos owns The Washington Post.)

Companies that have banked on cable viewers willing to pay extra have branched out, too. HBO recently launched an online-only service, HBO Now, and even niche producers such as World Wide Entertainment, which traditionally made money from pricey pay-per-view wrestling matches, have started to find success with cheaper online subscriptions.

This week’s sell-off began with Walt Disney Co., the owner of ABC and ESPN, which sank despite beating Wall Street expectations by expanding its quarterly profit 11 percent.

Investors were spooked when Disney chief executive Bob Iger said the company’s sports broadcast giant, ESPN, had lost a “modest” number of subscribers, mostly because they canceled their cable packages outright, and Disney trimmed its expectations for ESPN’s subscriber growth.

“We’re realists about the business and about the impact technology has had on how product is distributed, marketed and consumed,” Iger told investors. “We’re also quite mindful of potential trends among younger audiences in particular, many of whom consume television in very different ways than the generations before them.”

But that acknowledgment rippled through the industry, Martin said, because ESPN has generally been seen as a safe place in the TV business: Sports are hugely popular, giving the network a top spot in the ratings, and sporting events are usually watched live, meaning fewer people can fast-forward through commercials.

“It basically raised the specter that no one’s safe,” Martin said.