When a user profile shows a large negative reputation change from the "Voting corrected" line item, expanding the item shows the message "There were no net reputation changes on this day" despite the presence of other reputation change line items in the same day. See the below image:
In this case, there is obviously a significant net negative reputation change. It's possible in other cases there could be a net positive reputation change for that day.
If it is impractical to show details about the "4 events" cited in the line item, the next best thing might be to change the message that's shown when you expand the item to indicate that the details are unavailable.