Weazzzzzzz, copy and pasted from stockcharts. It splains better than I can about "overlays".
How do I overlay one chart on top of another?
Overlaid charts are charts that have two different datasets (i.e. a stock or an indicator), plotted on top of each other in the main charting window.
There are limits on the number of datasets that each group can request: Free users can see up to 2, Basic members can see up to 4, and Extra members can see up to 6 per chart.
To overlay one stock on top of another stock: Add a "Price" indicator to your chart and change its "Position" setting to "Behind Price", then click Update. The scale of the overlaid stocks will appear on the left. To adjust the vertical size of the overlaid stock, pull-out the Advanced settings for the Indicators, and change the "Height" value for the corresponding Price indicator.
To overlay an indicator on top of your main stock: Add whatever indicator you want to your chart and change its "Position" setting to "Behind Price", then click Update. The scale of the overlaid stocks will appear on the left. To adjust the vertical size of the overlaid stock, pull-out the Advanced settings for the Indicators, and change the "Height" value for the corresponding indicator.
To plot an overlay on top of an indicator: Open the "Advanced Options" section to the right of the indicators and select the overlay you want from the dropdown, then click Update. (Only available to members)
To overlay an indicator on top of an unrelated indicator: Add two indicators to your chart and change the "Position" setting of the second indicator to "Behind Ind.", then click Update. The scale of the second indicator will appear on the left. (Only available to members)
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