Citi CEO Jane Fraser has a Warren Buffett-approved trick for dealing with a toxic boss or difficult colleague: ‘Never in anger, respond to that email’

Even at the top of the business ladder, CEOs are still learning how to lead more effectively—and often turning to their peers for guidance. For Citigroup CEO Jane Fraser, that guidance came from legendary investor and former Berkshire Hathaway head Warren Buffett, who once shared with her two pieces of advice for handling difficult people and tense workplace situations.

The first? “He said, ‘You can always call them an asshole tomorrow.’ Really good piece of advice,” Fraser recalled...