Wall Street is watching closely to see exactly how Facebook plans to use the information offered every day by its more than 900 million users. The company brought in $1 billion in revenue in the first quarter, the vast majority of it from advertising, but it has not disclosed what portion of that is from sponsored stories.

Facebook recently began to show sponsored stories in the site’s main news feed and in its mobile apps, where they appear a lot less like traditional ads, though they do bear a “Sponsored” label. It has told investors that consumers were 50 percent more likely to recall an ad if it came with a plug from a Facebook friend. And it has made clear to users that while they can change a privacy setting so their “likes” do not appear under ads in the most prominent advertising zone on Facebook pages, they cannot turn off other kinds of endorsements that show up elsewhere. “Because sponsored stories are just stories from the news feed, you cannot opt out of them,” Facebook explains in its help center.

A company spokesman said that users can choose not to click the “like” button next to something if they don’t want to be associated with it, and in general they can use the privacy settings to control who sees what they do.

Amit Shah, a marketing executive with 1-800-Flowers, said sponsored stories had been remarkably effective in drawing new eyes to the company’s Facebook page, especially on lucrative occasions like Mother’s Day. He said the company did not need to obtain permission from its fans to run such ads.

“The person has given their consent because they’re engaging with your brand page, and you’re boosting that engagement,” he said. “Our experience is that people love hearing stories of other customers.”

For marketers, sponsored stories save money. No creative work is involved. All they are doing is leveraging one user’s stated preference — whether for a lubricant or a political candidate — and spreading the word to that user’s friends. The most frequently used trigger for such ads in sponsored stories now is the vague, broad “like” button.