If Jeremy Grantham is talking about a US ‘superbubble’, we should listen

The Boston-based fund manager has hard-to-deny evidence to back up his prediction of a wild rumpus'

Jeremy Grantham's warning that share prices are heading for a mighty fall is just part of the new year financial calendar, say his critics. On this occasion, however, the British co-founder of Boston-based fund manager GMO and highly regarded observer of stock market bubbles, may have got his timing spot-on.

Certainly Let the Wild Rumpus Begin" was a terrific title for Grantham's piece last week: a rumpus is roughly what we're seeing, at least if one looks at the US, where the technology-heavy Nasdaq has lost 16% since the start of January. It was clobbered so severely on Monday that even the UK's FTSE 100 index, a decidedly non-tech collection of stocks, was obliged to react to the apparent shift in investor sentiment. The Footsie lost 187 points, or 2.6%, even if a possible Russian invasion of Ukraine was also in the mix.