Jeremy Grantham's latest piece set off a lot of discussions this past week. Grantham examines how the market could perform if it followed a similar trajectory to historic bubbles. A key characteristic would be further price acceleration - an increasingly faster melt-up. Of course one could argue that this was already the case in 2017.
You can find the full GMO piece here:
Jeremy Grantham (GMO): Bracing Yourself for a Possible Near-Term Melt-Up
Grantham's personal view: