Nasdaq-100

The Nasdaq-100 tracks roughly the 100 largest companies listed on Nasdaq, excluding financial companies such as banks. It is heavily weighted toward technology, but also includes companies from consumer services, health care, industrials and other sectors. Because some companies have more than one share class, the index can contain slightly more than 100 securities.

The index was launched in 1985 and is maintained by Nasdaq. It uses a modified market-cap weighting: larger companies count more, but rules cap the weight of the very biggest members to limit concentration. Membership is reviewed annually in December, and weights are adjusted quarterly or when caps are exceeded.

The Nasdaq-100 is a popular benchmark for large growth and technology companies and is tracked by some of the most heavily traded ETFs in the world, as well as by futures and options.

It is often compared with the S&P 500. Because of its concentration in fast-growing tech companies, the Nasdaq-100 has tended to be more volatile, rising more in strong markets and falling more in weak ones.

It differs from the much broader Nasdaq Composite, which includes thousands of stocks.