When does the gravy train end?

A couple charts: One of the S&P 500 and one of the TSX Composite over the past year:

Over the past half year has been a straight trendline up. Naturally anybody that has invested in anything has seen the winds of the marketplace at their backs. The only question is – when does it end?

The economic recovery is being priced in – in addition to cash being deployed in assets that will yield any sort of return. The only question now is whether this is a rational valuation, or whether these prices have not priced in future unknowns – or perhaps the existing prices have not priced in enough of a recovery and we will continue to see a monster run continue in the indexes.