There are quite a few posts on here on meta about negative reputation, that received downvotes as they confused time-interval reputation (weekly, monthly, yearly) with all-time reputation.
All time reputation is said to be always >= 1. I believed that until I ran into the following graph:
Zooming in will leave us with this:
The graph is located at the reputation tab on the network profile of one such case (in case this will be fixed or removed, here's an archived version).
This graph leaves no room for interpretation: it displays negative all-time reputation over a short amount of time.
What allows for the existence of negative overall-reputation? Is reputation only reset to 1 every once in a while, if you are below that? Was the system overwhelmed at that point, for some reason unable of handling the amount of downvotes?
I believe this requires a fix, if it hasn't already been noticed / fixed.