The index ranks the combined infrastructure assets in the hands of the biggest public and private organisations.
In contrast to the Forbes Global 2000 ranking, the Bentley Infrastructure 500 ranks companies according to their reported tangible fixed assets (or other comparable noncurrent physical assets such as buildings or fixed structures, land, and machinery) - and is a direct measure of the infrastructure owned and operated by an organization.
[3] Infrastructure Value above as measured by reported net tangible fixed assets.
The Bentley Infrastructure 500 index shows little correlation with the Forbes 2000 - showing that the biggest companies in the world are not necessarily the biggest owners of fixed assets.
The 2010 study showed that the combined assets of all the 500 companies add up to US$ 13 trillion, which is equivalent to annual GDP of the United States.