Dow Jones Industrial Average
Only one company remains in the index from the beginning - General Electric.
 The 12 original constituents
The index is unusual in that it is weighted by price. It is calculated by adding up all the prices of the 30 stocks and dividing by an arbitrary divisor.
The divisor started off at 30, but over time this has been adjusted to reflect capital changes such as stock splits and is currently about 0.2.
Consequently companies with the highest stock values have the great influence, and not those with the largest market values - which comes as a suprise to many people.