Display differences in value across different data sources

I am displaying performance values in a hierarchical grid (infragistics' xamTreeGrid) for various instruments from a well defined primary data source.

<Fund1>           P&L
|-<Instrument1>   100 <-- Red bg, tooltip saying: diff dataSource1 vs. dataSource2: -30
|-<Instrument1>   200 <-- transparent bg, as there's no diff
...

There would be two other data sources to which we want to compare the displayed values and indicate differences above a certain threshold.

The idea is not to have a side by side comparisons but instead, an indication that there is a discrepancy between the data sources, that can be investigated afterwards.

I am making the value's background red and provide a tooltip that shows the actual differences.

Are there any better ways of visualizing these differences? I'm thinking in terms of making it compact and intuitive for the users, to see the magnitude of the difference and the other sources it is compared against.

I have great flexibility in WPF to customize the field however works best.