A Linear Regression line is a “best fit” line modeling a scatter plot of data. One can think of it as the equilibrium line of a set of data points. As used in technical analysis, it simply offers an indication as to the general direction of the underlying issue over a designated period of time.
This Linear Regression line has been manually created after determining its plot with another charting service. You can see it simply offers an idea as to the general direction of the underlying issue over a specified period of time. In this case a negative divergence occurred. As the stock trended up, the RSI flattened out and began to move down. INTC then headed down.