The add function allows users to overlay additional symbols or data series on top of an existing chart. This differs from the compare function in that the chart does not change the vertical axis from price to percentage and auto-scale to fit both. The vertical axis stays aligned with the chart's original data series. The new symbol/data series is merely overlaid on top. This allows for the actual price value of both data series to be visible, without the chart collapsing if the values are too far apart. The add function is good for visual comparisons between two or more symbols.
Below is an example of a chart containing EURUSD and EURJPY.
Using the add function has become increasingly popular because it has the ability to compare market trends for several similar or related instruments simultaneously. For example, analyzing two different gold tracking ETFs to spot minor differences.
Below is a chart example, containing two separate gold tracking ETFs. It is clear that they are closely related, but further examination reveals that minor differences do occur.
To add a new symbol to overlay on top of the current data series/chart, simply click on the Add button on the toolbar along the top of the chart and type the symbol into the dialogue box and click the + sign.
Another option is the Overlay the main chart feature. If this is unchecked, the new symbol will not be overlaid on top of the original data series, rather it will be sent to a new panel beneath the original one. This allows for greater control of each data series, even though it can hinder direct, visual comparisons.