Highlight Subtotals

I have a macro that I created that sorts out information by groups. It combines twenty different spreadsheets, then sorts and groups the data. The data is different every day. I found a piece of code online that adds subtotals to those groups of data. It is very concise and works perfectly. I need to call attention to the subtotals if they are negative. If I use conditional formatting it highlights all negatives. There is so much data that I need to be able to pinpoint only the negative subtotals. Is there a way I can add something to the code to highlight the line if it is negative. Here is the attatched piece of code.

For Each NumRange In Columns("L").SpecialCells(xlConstants, xlNumbers).Areas SumAddr = NumRange.Address(False, False) NumRange.Offset(NumRange.Count, 0).Resize(1, 1).Formula = "=SUM(" & SumAddr & ")" c = NumRange.Count 
Next NumRange