X Just Changed What Shows Up in Your Timeline

Image: Elon Musk/X

X has changed how it picks posts for your timeline, rolling out a new ranking model that’s better at predicting how long you’ll spend on a post and a new retrieval model built to find posts people actually read to the end.

That’s according to a post from Elon Musk on X on Monday evening, where he described the two updates as “important changes to timeline recommendations.” He listed them as a “New AI/SI ranking model that predicts probable time spent much better” and a “Retrieval model trained to surface posts people read all the way through.”

Musk paired the post with a chart of daily user active seconds, a measure of how much time people spend on X, comparing 2026 with the three years before it. “User active seconds is growing exponentially and hitting all-time highs almost every day,” he wrote.

The two models handle different jobs, since retrieval is the step that pulls a pool of candidate posts from across X, and ranking decides what order they show up in. Musk’s description suggests both are now leaning harder on whether a post holds your attention, not just whether you tap on it. He didn’t say exactly when the change went live or how time spent is weighed against likes, replies and reposts.

The update is the latest in a long run of changes to X’s recommendations. Back in October 2025, Musk said the company was aiming to delete all of the heuristics in its recommendation system and that “Grok will literally read every post and watch every video” to match people with content they’re likely to find interesting. In January, he predicted the AI recommendation system “will be great by mid year and absolutely incredible by end of year.”

X has also been publishing its algorithm on GitHub along the way, after Musk said in January that the code deciding which organic and advertising posts get recommended would be open sourced, with updates every four weeks and developer notes explaining what changed. In May, he posted that the latest version was up on GitHub and reminded users that “you can always choose no algorithm via the Following tab.” Over the summer, he went further, saying X would open source its entire codebase and invite third-party reviewers to confirm the published code is what’s actually running.

The X changes come as SpaceXSI, the company behind Grok and Grok Bot, pulls its products closer together. Earlier this month it launched The X Subscription, a single plan bundling Grok, Grok Bot, Cursor and X Premium, two days after the company renamed its X account from @SpaceXAI to @SpaceXSI. Grok Bot also picked up the ability to search, read and monitor X on its own on October 7.

Musk hasn’t said whether the new models will show up in the next open-source release of the algorithm on GitHub.

Have you noticed a difference in what’s showing up in your For You feed this week?