[1][2] The list was calculated by combining five factors: sales, profits, assets, market value, and employees.
[3] The list was last issued in March 2003 (based on 2002 data for the companies); it is no longer calculated each year and has been replaced by the Forbes Global 2000, which includes non-U.S. companies but is calculated on a similar basis as the old Forbes 500 (although it does not include employees).
The value of a firm's assets is typically derived from a company's ability to generate cash via its ownership and control of inputs and/or distribution of the final product.
This method is heavily biased towards distributors such as Walmart, which may have a high volume of sales but may be operating on very thin profit margins.
At one point in the late nineties, Cisco Systems would have been the biggest company by this measure, however the dot-com bubble crash reduced its perceived value dramatically.