The Globe and Mail reports in its Friday edition that between the initial public offering of SpaceX and the tentative peace deal with Iran, investor enthusiasm for stocks has put a key valuation metric within spitting distance of its worrying all-time high. The Globe's Jason Kirby writes that the Shiller price-earnings ratio for the S&P 500, which captures a longer-term view of corporate earnings power than conventional valuation metrics, now sits at 41.3, just a notch below the 44.2 level reached in December, 1999, peak of the dot-com bubble. By comparison, over the last century, the ratio average was 19. The Shiller P/E ratio relies on 10 years of inflation-adjusted earnings for its gauge of corporate profits. The S&P 500 still looks relatively inexpensive when measured using forward earnings. At roughly 21 times expected earnings over the next 12 months, the S&P 500 sits only a few percentage points above its 30-year average of 17.1. The caveat is that the majority of that profit growth is being driven by a small number of megacaps in the tech sector. That leaves investors in a difficult position when gauging how much higher the market could go. History suggests the peak could be dangerously close.