These 4 market sectors look frothy — and Nvidia’s isn’t even the biggest bubble

A MarketWatch column analyzes an academic study linking large trailing two-year outperformance (alpha) to elevated crash probabilities for industry groups. Using State Street’s “froth forecasts,” the S&P 500 is assigned about a 30% chance of a 40%+ drop over the next two years, roughly in line with recent five-year averages. However, four S&P 1,500 sub-industries show trailing two-year alphas of 100+ percentage points — notably electronic components (driven by Corning and Amphenol), construction & engineering (Quanta, Comfort Systems), diversified metals & mining and semiconductors — implying materially higher crash odds for those sectors. The piece flags sector-specific froth rather than a broad-market bubble, signaling elevated downside risk concentrated in a handful of industries that could drag on S&P performance if reversals occur.