Which U.S. technology index peaked on March 10, 2000, marking the start of the dot-com crash?

The U.S. technology-heavy index that peaked on March 10, 2000, as the dot-com crash began was the Nasdaq Composite.

The Nasdaq Composite closed at 5,048.62 on March 10, 2000. During the late 1990s, investors poured money into internet companies, often valuing firms on expected future growth rather than profits. The index became a widely watched measure of that enthusiasm because many technology and communications companies traded on Nasdaq.

After the peak, the Nasdaq fell sharply as investors reassessed unrealistic business plans, rising interest rates, and companies that could not generate sustainable earnings. The crash unfolded over several years rather than in one trading session. Many internet startups failed, while a smaller group of companies survived and later became major businesses.

The Nasdaq Composite is not the same as the Nasdaq-100. The Composite includes thousands of Nasdaq-listed common stocks, whereas the Nasdaq-100 tracks 100 of the largest nonfinancial companies listed there. That distinction is a common source of confusion when discussing the dot-com era.