The cost of completing Sarbanes-Oxley corporate governance legislation has risen to $5.1m (€4m) for the average large US company, with a further $3.7m in ongoing compliance bills.

The vast bulk of this cost relates to updating and documenting internal management controls the final stage of a controversial reform process that applies to companies reporting from Monday. Some very large companies such as General Electric say they have spent $30m on this alone.