Instagram, a photo-sharing app, is overhauling its feed with a new personalized algorithm and follows Twitter and Facebook in introducing formula that prioritizes photos based on a user's interests, friends, and other data

Starting Tuesday, a small percentage of Instagram's 400 million users had their feeds reordered, with posts that Instagram thinks they are most likely to find interesting at the top of their feeds.

 "The order of photos and videos in your feed will be based on the likelihood you'll be interested in the content, your relationship with the person posting and the timeliness of the post," Instagram announced the change on its blog.

"If your favorite musician shares a video from last night's concert, it will be waiting for you when you wake up, no matter how many accounts you follow or what time zone you live in. And when your best friend posts a photo of her new puppy, you won't miss it."

Kevin Systrom, the co-founder and chief executive of Instagram, told The New York Times that companies need to take action to handle the massive amounts of content coming through.

"On average, people miss about 70 percent of the posts in their Instagram feed. What this is about is making sure that the 30 percent you see is the best 30 percent possible."

The change is a risk for Instagram, which has won over users with its simplicity. Instagram's U.S. user base is expected to grow 15% in 2016 to just over 89 million people who use the service at least once a month, compared with just 3.1% for social networks overall, according to eMarketer

For now, Instagram users in the test will not be able to opt out of the reordered feed, a spokesman said. In addition to likes, comments ,and sea rches, Instagram will also factor in users' "relationship with the person posting and the timeliness of the post" in determining what will appear at the top of their feeds. It does not take into account a user's activity on Facebook.