The best advice Warren Buffett gave the CEO of American Express

Being CEO is supposed to be a solitary job, but it’s helpful to consider investment prophet Warren Buffett as a trusted advisor.

That’s the summary of

American Express

(code: AXP) chief executive Stephen Squeri, who recently sat down with Barron’s Andy Serwer. by Buffett

Berkshire Hathaway

is American Express’s largest shareholder, holding about 20% of the shares, according to FactSet data.