On Market Bubbles And The Trickier Strategy Of Knowing When They'll Go Bust

 | Jul 22, 2021 01:07AM ET

Jeremy Grantham is chairman of the board for the well-known asset management firm,  Grantham, Mayo, & van Otterloo (GMO). Yet he is much more than that. He is also an accomplished “bubble-ologist.”

In a recent interview, Grantham said:

“Bubbles are unbelievably easy to see. Knowing when the bust will come is trickier.”

For instance, long periods of unbridled success tend to breed unchecked speculation. More and more investors engage in borrowing to leverage prospective gains with stock loans and leveraged instruments.

Historically, however, margin debt peaks often occur shortly before stock bubbles burst. Will this time be different?