While browsing Stack Overflow, I noticed that I lost a lot of reputation:
Is this serial downvoting? Will it be corrected by a rep-recalculation? How often are those done?
Here's a second instance:
That's serial downvoting.
There are three ways to fix it:
If it was serial down-voting it should be spotted, and corrected, by the automatic processes that run.
Addressing a specific concern expressed in a duplicate question - note that based on details of a particular incident that involved serial voting, it is most likely that vote reversal script uses some data about prior abuse.
In other words, the guy who serially voted you once, will have harder time trying it next time, even if they vote less.
In the incident mentioned above, vote reversal script has been caught at cancelling a "series" of 2 (t-w-o) votes. The only feasible explanation for this is that script somehow took into account that suspected votes came from someone previously caught at abusive voting at the same "target poster".
Screen shot below shows a sequence of vote reversals that are likely done at "script time"
My reading for the data shown at screen shot is as follows. There's
+4 entry revealing that reversal has been done for at least two users. And since total amount of votes reversed is
(4+2+2+2)/2=5, this means that at least one of reversals has been done for a user who voted less than 3 times.