user23596: Magnus just withdrew from the Sinquefield Cup. Does that affect his rating at the end of the tournament? Will he gain or lose rating based on at the time he left the tournament in the next fide update?
Side question - Does that also mean that Nepo's and Aronian's results will be converted as win (without rating changes) because otherwise it will be unfair in a round-robin situation?

user28052: To answer your side question, the competitors who faced Magnus already will have their results annulled (but still count for rating points), and the competitors who haven't faced Magnus yet will get a bye. Effectively this is now a "9 player tournament" where all the matchups with Magnus are now treated as byes.
Source: Saint Louis Chess Club Executive Director Tony Rich Interview on Day 4
Nepo benefits since his round 1 loss against Carlsen is erased, while Niemann is hindered since his surprise win against Carlsen is also erased. Aronian drew against Magnus so he neither gains nor loses.
Caruana interview: "Ian is obviously the biggest beneficiary in terms of the tournament"

user4418: The simple rule is that FIDE rates games where at least one move has been made and the FIDE Laws of Chess applied. You can read the full rules here. That means that his next FIDE rating will be based on the games he has played so far this month plus any more he might play. The only way you can gain or lose rating points is by playing FIDE rated chess.

Does that also mean that Nepo's and Aronian's results will be converted as win(without rating changes) because otherwise it will be unfair in a round-robin situation?

This is covered in the FIDE Tournament Rules:

6.6 Round robins
(1) Each player has entered into a contract to play throughout the tournament.
(2) When a player withdraws or is expelled from a tournament, the effect shall be as follows:

If a player has completed less than 50 % of his games, the results shall remain in the tournament table (for rating and historical purposes), but they shall not be counted in the final standings. The unplayed games of the player are indicated by (-) in the tournament table and those of his opponents by (+). If neither player is present this will be indicated by two (-).
If a player has completed at least 50 % of his games, the results shall remain in the tournament table and shall be counted in the final standings. The unplayed games of the player are shown as above.


So, completed games will be rated. If Carlsen has completed 50% of his games then his remaining opponents will have their results against him recorded as wins for the tournament but not rated, since no moves were played. In effect he has defaulted his remaining games.

23596: <p>Magnus just withdrew from the Sinquefield Cup. Does that affect his rating at the end of the tournament? Will he gain or lose rating based on at the time he left the tournament in the next fide update?</p>
<p>Side question - Does that also mean that Nepo's and Aronian's results will be converted as win (without rating changes) because otherwise it will be unfair in a round-robin situation?</p>
 28052: <p>To answer your side question, the competitors who faced Magnus already will have their results annulled (but still count for rating points), and the competitors who haven't faced Magnus yet will get a bye. Effectively this is now a &quot;9 player tournament&quot; where all the matchups with Magnus are now treated as byes.</p>
<p>Source: <a href="https://www.youtube.com/watch?v=VElLYxf08C0" rel="nofollow noreferrer">Saint Louis Chess Club Executive Director Tony Rich Interview on Day 4</a></p>
<p>Nepo benefits since his round 1 loss against Carlsen is erased, while Niemann is hindered since his surprise win against Carlsen is also erased. Aronian drew against Magnus so he neither gains nor loses.</p>
<p><a href="https://www.youtube.com/watch?v=hXm530tI-B8" rel="nofollow noreferrer">Caruana interview: &quot;Ian is obviously the biggest beneficiary in terms of the tournament&quot;</a></p>
 4418: <p>The simple rule is that FIDE rates games where at least one move has been made and the FIDE Laws of Chess applied. You can read the full rules <a href="https://handbook.fide.com/chapter/B022022" rel="noreferrer">here</a>. That means that his next FIDE rating will be based on the games he has played so far this month plus any more he might play. The only way you can gain or lose rating points is by playing FIDE rated chess.</p>
<blockquote>
<p>Does that also mean that Nepo's and Aronian's results will be converted as win(without rating changes) because otherwise it will be unfair in a round-robin situation?</p>
</blockquote>
<p>This is covered in the <a href="https://handbook.fide.com/files/handbook/Competition_Rules.pdf" rel="noreferrer">FIDE Tournament Rules</a>:</p>
<blockquote>
<p><strong>6.6 Round robins</strong><br />
(1) Each player has entered into a contract to play throughout the tournament.<br />
(2) When a player withdraws or is expelled from a tournament, the effect shall be as follows:</p>
<ol>
<li>If a player has completed less than 50 % of his games, the results shall remain in the tournament table (for rating and historical purposes), but they shall not be counted in the final standings. The unplayed games of the player are indicated by (-) in the tournament table and those of his opponents by (+). If neither player is present this will be indicated by two (-).</li>
<li>If a player has completed at least 50 % of his games, the results shall remain in the tournament table and shall be counted in the final standings. The unplayed games of the player are shown as above.</li>
</ol>
</blockquote>
<p>So, completed games will be rated. If Carlsen has completed 50% of his games then his remaining opponents will have their results against him recorded as wins for the tournament but not rated, since no moves were played. In effect he has defaulted his remaining games.</p>
