http://www.djindexes.com/mdsidx/downloads/fact_info/Dow_Jones_Industrial_Average_Fact_Sheet.pdf
Stated Objective
To represent large and well-known U.S. companies. Covers all industries with the exception of Transportation and Utilities.
Key Features
The index is maintained by the Averages Committee.
Components are added and deleted on an as-needed basis. For the sake of continuity, such changes are rare, and typically occur following corporate acquisitions or other significant changes in a component company’s core business. When one component is replaced, all of them are reviewed.
While stock selection is not governed by quantitative rules, a stock typically is added only if the company has an excellent reputation, demonstrates sustained growth and is of interest to a large number of investors. Maintaining adequate sector representation within the index is also a consideration in the selection process.
The index is price weighted.
The Dow Jones Industrial Average was first calculated on May 26, 1896.
I wish I would have put a bunch in Alcoa when it fell out of their objective. ;^)