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Access to the Watch list is trough the Market Data drop down menu on the toolbar or via the keyboard shortcut CTRL+2 or F6.
To add an instrument to the Watch List, click the cog on the toolbar 
This will open up a My Lists window. To make a new custom list click on New list.
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By typing the first letters of an instrument, Kodiak Pro will suggest stocks and bonds to add to the Watch List. To add the instrument to your new list press Add or press enter on your keyboard.
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To add an instrument to an excisting list, select the list in the drop down menu next to List.
Remove an instrument from the list by double clicking the instrument name.
You can also edit, remove and rename a custom list.