I set up a custom cell format to bring forward (1.) the sum a cell, which is
a DATE and (2.) the sum of a different cell, which is a %. However, the
program is taking the luxury of converting the -% data to a positive %
number. Why is this, and how can I correct it?

The Custom cell format is as follows: m/dd/yy;0.00%

Any help would be greatly appreciated.