For Marc Faber, editor of the Gloom, Boom & Doom Report, the answer is clear. In fact, he says the bubble may already be bursting.
"I think it's a colossal bubble in all asset prices, and eventually it will burst, and maybe it has begun to burst already," Faber said Tuesday on CNBC's 'Futures Now' as the S&P 500 lost ground for the second-straight session.
Of course, Faber has long been expecting a market decline. But for the precise reason that stocks have simply continued to rise, he's now become even more bearish.