I think it will go up for a little while yet, because people are convinced that this is a zero risk investment with guaranteed returns- like real estate was supposed to be. I mean, how could all those companies in the index fund, with all that 401k money pouring in, go down at once? Seems impossible to imagine. That's why it's developing into a bubble.

My worry is that some of these stock prices are being supported by leveraged buybacks at inflated prices, and when the economy goes into a recession, you might see a lot of companies declaring bankruptcy at the same time, being unable to repay those loans, leading to solvency issues with the banks that issued the loans. That's the nightmare scenario.