This mode sets the Chart Type to Line and returns the value of each symbol as a percentage change calculated starting from a specified date. This is particularly useful when making a precise comparison of the relative strength of multiple symbols.
to specify a start date for the chart, right-click in the chart window and highlight time template, then select edit.
click on the + icon in the upper lefthand corner of the window. input a name in the name field . in this example, we will use ytd since we want to display the performance since the beginning of the year. next, we will select start date/time and enter 01/01/2021. lastly, we click the close button.
to compare the performance multiple symbols such as aapl to spy, right-click on the chart and select insert symbol (aapl, for our example) and check the box to overlay the main chart: