Powerpoint charting using positive and negative numbers

[NumbersMax]

All,

My boss is trying to create a pie chart using a group of 4 numbers that are both positive and negative and sum to a negative number. I'm having difficulty even imagining how a pie chart could properly display that information.

Any ideas?...or perhaps a different type of graph would be in order like a bar or area graph. I'm really have trouble visualizing it.

Thanks,
Max