Gen Zers are no doubt baffled by such recent headlines as “Fed Chair Powell just had his ‘irrational exuberance’ moment, Ed Yardeni says,” and “Did Jerome Powell Just Say ‘Irrational Exuberance’?” Those headlines refer to a long-ago event involving a previous Fed chair, dizzyingly high stock prices, and an eventual market crash. But beware: Some market soothsayers misinterpret that earlier episode, and getting it wrong could misguide today’s investors. The headlines were sparked by a Powell appearance w ...