The Dow Jones sector classification comprises four levels:
- economic sectors,
- market sectors,
- industry groups, and
- sub groups
It is altered periodically to reflect changes in sector and developments in the stock market.
Economic sectors and market sectors, the first two levels, which have a high acceptance in the investment community, will remain unchanged. These sectors are widely used for index-linked investment products such as exchange-traded funds and derivatives.
On the third level, the number of industry groups will be raised to 51 from 40. And the fourth level sub industry groups will increase to 89 from 70. Most of the changes will occur in the third and fourth levels of two market sectors: Industry Goods & Services and Technology.
These classification changes will be effective at the opening of trading on December 24, 2001 with the fourth-quarter review of the Dow Jones and Dow Jones STOXX indexes.