A report in September from the nonprofit ChangeAdvertising.org found that 41 of the top 50 news sites — including The Guardian, CNN, Time and Forbes — embed widgets from so-called content-recommendation companies. Several of those that do not, including The New York Times, pay for content created with advertisers in-house to appear in the widgets to increase traffic to their own sites.

The companies Taboola and Outbrain, both founded about a decade ago in Israel, dominate the industry, followed by Revcontent and ZergNet, according to data analysis firm Datanyze. (The Times has a “From Our Advertisers” section on its home page that leads to posts created by its ad department without participation of the news and editorial staff.)

ChangeAdvertising.org analyzed the content ads on those 41 news websites and found that 61 percent came from advertisers or other prominent publishers. But 26 percent led to “clickbait” sites that were covered in more ads and lower-quality recommendation widgets featuring sexually suggestive or interruptive images. Almost all of those sites, which appear to be paying for placement, then profiting from their own ads once people visit, hid their domain registrations.

Sean Blanchfield, chief executive of PageFair, an advertising start-up, referred to the ad-filled sites as “arbitrageurs” that are “basically designed to try and get the user to click on something.”

Rob Leathern, a board member at ChangeAdvertising.org, called it “a pretty problematic state of affairs.” He said it was surprising that such pages were “one click away from these top 50 news sites.”

Readers are starting to express discontent. One recently criticized the Outbrain links next to a Slate article about preventing eating disorders — one of which was titled “6 Tips to Avoid Thanksgiving Weight Gain.” Another was shocked by a Taboola link headlined “Meet the Women Making Rape Jokes That Are Actually Funny” under a Fusion news story about an underage rape. (That example was not a paid ad from Taboola; rather, it was a Fusion article resurfaced by Taboola technology, which is another part of the company’s business.) One Twitter user asked The Guardian in April: “Don’t these @Outbrain articles kind of undermine the integrity of news outlets?”