Thanks for your reply.

I somewhat understand what you have done. What I don't get is the mechanics of how the cells in A5:A16 get the appropriate colors assigned. Can you please let me know how this step is done?

Thank you.

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Activate a cell in column B with prices, and select from Menu Home>Conditional Formatting>Manage Rules. 5 rules (a rule for every color) are defined there.

When you want to apply conditional formatting to columns C and D too, you need additional 2 calculated columns with previous workday values for those columns, and additional 5 conditional formatting rules for every of those columns.