It’s Money Rule No. 42. You shouldn’t shop or invest when you’re angry, and here’s why you should stay calm, cool and collected when your money is on the line.

Anger, research shows, makes you more optimistic, more of a risk-taker than you would naturally be, and that means that you’re more likely to say, “What the hell,” to unfortunate purchases. Or, to spend or invest money on a whim — bad move!

Wait until you’re calmer, cooler and more collected before making financial decisions.