What changed in the X algorithm in July 2026?
X started giving original posts an extra push in the feeds of mutual follows, people who follow each other. On 13 July 2026, Nikita Bier, then X's head of product, posted that X was rolling out a small tweak to boost the visibility of your posts to your mutuals, which Bier defined as people you follow back. Bier added that it "should also help clusters form around interests more easily". TechCrunch reported the change the same day.
X's open-source code for the For You feed shows exactly what the tweak does. A document X added to its algorithm repository on 13 August 2026 calls it the bidirectional follow boost and explains it in plain language: it boosts original posts from people you mutually follow by increasing the weight on the predicted probability that you will reply to them. The same document gives this timeline:
| Date | What X did, per its repository |
|---|---|
| 10 Jul 2026 | A/B test began: a small percentage of users got boost values of 5, 10, 15 or 20; most users stayed at 0, meaning no boost |
| 13 Jul 2026 | After initial results, a boost of 20 rolled out to many users, while tests of other values continued |
| 24 Jul 2026 | Boost lowered to 15, after experiment results and feedback such as people seeing less World Cup discussion from accounts they didn't follow |
| 20 Oct 2026 | The repository's settings file still sets the boost at 15 (checked today) |
A second boost, on dwell time, was tested in the same experiment and not shipped more broadly. Bier said on 5 August 2026 that they were stepping back from leading product at X and would stay on as an adviser. X says it runs scripts that set the repository's defaults to its primary production values, and on 20 October 2026 the boost was still there.
How does the X algorithm rank posts in 2026?
X's For You feed predicts what you will do with each post and adds those predictions up. The repository's README says a model called Phoenix reads your recent engagement history and predicts, for each candidate post, how likely you are to like it, reply, repost, quote, share, dwell on it, follow the author, mute, block or report. Each prediction is multiplied by a weight, and the weighted sum is the post's score. These are the main weights in the settings file, checked 20 October 2026. The like weight itself rose from 0.5 to 0.66 in commits on 13 and 14 October 2026:
| Predicted action | Weight |
|---|---|
| Reply to an original post from a mutual follow | 5 + 15 = 20 |
| Share via copy link | 20 |
| Reply (any other post) | 5 |
| Quote | 5 |
| Share via DM | 5 |
| Follow the author | 4 |
| Repost | 1 |
| Like | 0.66 |
| Report | -234 |
X warns against reading these as exchange rates. The weights multiply predicted probabilities, not counts of actions, so a weight of -234 does not mean one report cancels out hundreds of likes; the code comments add that a report's baseline probability is more than 1,000 times lower than a like's. What the table does show is direction: per unit of predicted probability, a reply carries more weight than a like, a repost or a follow.
Four other rules in the README matter to a founder:
- Followers come first. Posts from accounts the viewer doesn't follow are multiplied by a factor below 1.
- In For You, replies reach only followers. For You drops replies and reposts from accounts the viewer doesn't follow, and discounts them from accounts the viewer does follow.
- 48 hours. Posts older than 48 hours are filtered out of For You.
- One author at a time. Each post after an author's first in a feed is multiplied by a decaying factor, and posts from authors with impressions below a threshold get a new-author boost.
What does the mutual follow boost mean for B2B founders?
Your original posts now get extra weight in the feeds of people you follow who also follow you, through the reply prediction only. Three consequences, from our reading of the code:
- Following back matters. The code that tags mutuals marks an author as a mutual only when the viewer follows the author and the author follows the viewer. A buyer who follows you gets the boost on your posts only if you follow them back.
- Original posts get it; replies and reposts don't. The eligibility check requires that the post is not a reply, not a repost, and from a mutual follow.
- Posts your peers will answer gain most. The boost raises the weight on predicted replies, so a post that people in your circle are likely to reply to gains the most. A post that collects likes and no replies gains least.
The practical shift is from chasing reach under big accounts to building a circle of mutual follows in your niche who reply to each other. Replies under a large account's post can still be read in that conversation, but in For You, replies from accounts a viewer doesn't follow are filtered out. Your own original posts, shown to mutuals likely to answer them, are where this boost applies.
Whom should you follow and reply to on X?
Follow and reply to people who are likely to follow you back and answer you: peers and buyers in your niche. A very large account is a poor target for this boost, because the boost needs the author to follow you back. Our advice on where to look:
| Who | Why they fit | How to find them |
|---|---|---|
| Followers you haven't followed back | One follow from you makes them a mutual | Your followers list, filtered to your niche |
| People who already reply to you | They have shown they will answer | Your notifications |
| Founders at your stage selling to the same buyer | Their posts cover problems you can speak to | Search your topic; check who replies under posts you read |
| Buyers who post about the problem you solve | A reply exchange with them is a conversation with a possible customer | Search the problem in the words they would use |
| Small newsletters and analysts in your space | They post original analysis you can reply to with substance | Bios that mention your topic |
Keep a list of about 30 accounts that fit, and add to it as people reply to you. Our guide to growing on X as a B2B founder covers profile and posting basics that this routine assumes.
A 30-minute daily routine for the mutual follow boost
Thirty minutes a day, split across five tasks. The routine is our advice, not X's.
Follow back your niche
Check new followers and follow back the ones who fit your list. Each becomes a mutual, so your original posts get the reply boost in their For You feed.
Reply to five mutuals
Open the profiles of five mutuals and reply to their original posts from the last 48 hours. Add a number, an example or a real question. A reply that would make sense as a short post on its own is the standard.
Follow three new people
Pick from the table above, starting with people who replied to you or to the same threads as you. Skip accounts outside your niche: they may follow back but are unlikely to reply.
Post one original post
Draft it the night before. Share something from your own work that your peers can answer, such as a number with a specific question about theirs. Don't ask for likes, replies or follows.
Answer every reply
Reply to everyone who answers your post the same day. Those replies are conversations with the people the boost is built around.
Once a week, take ten minutes to check three things: who replied to you, how many of them are mutuals, and which posts started conversations. That is the measure for this change. Neither Bier's post nor the repository gives a reach figure for the boost, so we don't promise one. For post ideas, our 32 X post and reply templates are a starting point.
If you want help keeping the routine, Siela's X Growth agent can like, reply, repost and follow from your own X account in your voice, and you can set engagement so it shows you each reply first. Replies are where your voice matters most on X, so read each one before it goes out.
What should you stop doing on X?
Drop the habits the boost doesn't reward. Four of them:
- Chasing viral threads from huge accounts. A reply there is not an original post, and in For You it can reach only people who follow you. Five replies to mutuals are a better use of ten minutes.
- Reposting instead of posting. The boost applies only to original posts. A repost of someone else's thread gives your mutuals nothing to reply to from you.
- Following everyone back. Mutuals outside your niche are unlikely to reply, and the boost runs on predicted replies.
- Engagement bait. Posts that tell people to reply or follow chase the same signal by force. If you are in X's Original Content Rewards programme, its rules bar repeatedly asking users to like, reply, bookmark, follow or repost.
Frequently asked questions
How does the X algorithm work in 2026?
X's open-source code says a model called Phoenix predicts how likely you are to take each action on a post, such as liking, replying, reposting or reporting, and adds those predictions using weights set in the code. Posts from accounts you don't follow are discounted, posts older than 48 hours are filtered out, and repeat posts from one author decay.
Does X boost posts from mutual followers?
Yes, for original posts. Since 13 July 2026, X adds a boost to the reply weight for original posts from authors you follow who also follow you. According to X's algorithm repository, the boost was 20 at launch and has been 15 since 24 July 2026, on top of a base reply weight of 5.
Who announced X's mutual follow change?
Nikita Bier, then X's head of product, announced it in a post on 13 July 2026, saying X would boost the visibility of your posts to your mutuals. On 5 August 2026 Bier said they were stepping back from leading product at X and would stay on as an adviser. The boost was still set in X's public code on 20 October 2026.
Do replies get the mutual follow boost on X?
No. X's code applies the boost only when a post is not a reply and not a repost, and its author is a mutual follow. In the For You feed, replies and reposts from accounts the viewer doesn't follow are filtered out, and those from accounts the viewer follows are discounted.
Should you follow back your followers on X?
Follow back the ones in your niche. X's code counts an author as a mutual only when the viewer follows the author and the author follows the viewer, so a relevant follower you follow back becomes a mutual and your original posts get the reply-weight boost in their For You feed. Mutuals outside your niche are unlikely to reply.
Sources
- Nikita Bier on X: mutuals visibility tweak (posted 13 Jul 2026)
- TechCrunch: X just tweaked its algorithm to make it more friendly, less battleground (published 13 Jul 2026)
- X algorithm repository: Example algorithm diff, bidirectional follow boost (checked 20 Oct 2026)
- X algorithm repository: README (For You feed algorithm) (checked 20 Oct 2026)
- X algorithm repository: home-mixer/params/param.rs (checked 20 Oct 2026)
- X algorithm repository: xai-value-model/inputs.rs (checked 20 Oct 2026)
- X algorithm repository: bidirectional_follow_hydrator.rs (checked 20 Oct 2026)
- Nikita Bier on X: stepping back from leading product (posted 5 Aug 2026)
- X Creators (@XCreators): Original Content Rewards Program (posted 7 Aug 2026 (8 Aug IST))
- Siela: 32 X post and reply templates (checked 20 Oct 2026)
- X algorithm repository: commit history of home-mixer/params/param.rs (checked 20 Oct 2026)