If Excel is not highlighting cells in the formula, enable 'Allow editing directly in cells' and 'Enable fill handle and cell drag-and-drop' in Excel options.

Learn how to highlight cells with negative values in Excel. Make negative numbers stand out in Red using Conditional or Custom Formatting.

How to highlight values Excel has a built-in conditional rule that highlights unique values. You don’t have to come up with a special formula—you just run though a few clicks.