Currently RadChart does not support financial indicators / trendlines out-of-the-box but these features are in our TODO list for the Q3 2010 release (around November).
At the moment the control supports manual drawing of custom lines & gridlines by adding CustomLine / CustomGridLine instances to the ChartArea.Annotations collection but note that if you would like to draw a regression line, you will need to make all necessary calculations on your own right now.
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