It happened exactly 25 years ago when the roughly five-year dot-com bubble popped, leaving trillions of dollars of investment losses in its wake. On March 24, 2000, the S&P 500 Index posted a record level it wouldn’t see again until 2007. Three days later, the tech-heavy Nasdaq 100 Index also closed at an all-time high, the last time it would do that for more than 15 years.