So, is the U.S. stock market in bubble territory ... rather than dividing by its reciprocal (see the chart below). The bubble detector has averaged 0.141 since January 1987.

The Nasdaq jumped more than 12%, its biggest single-day rise since the Dot-Com Bubble days ... While other asset classes did react to the stock market surge, those reactions weren’t very ...

Check. To many chart readers, it seemed like the latest technical signals were pointing to a fresh and lasting upswing in the stock market — but not so fast. The S&P 500 is approaching key ...

The key piece is the cohort of mega-cap tech companies that have long dominated stock-market performance ... a record 34% of S&P 500 market cap, as reflected in the chart below.

For example, the dot-com stock market crash in 2000 had a lot to do with investor frenzy over internet stocks, and eventually that bubble burst, causing a widespread stock market crash.