A newly released study of the costs associated with Sarbanes-Oxley compliance shows that Fortune 1000 companies have seen their auditing expenses skyrocket by more than $1.5 billion—with much of the increase attributable to SOX.

The study, conducted by researchers at the University of Nebraska at Omaha, compared the 2003 auditing costs of 648 companies with the amount they spent in 2004—and concluded that companies are forking over, on average, 67 percent more on auditors in the post-SOX era. The average Fortune 1000 company spent $5.78 million on audit fees in 2004, compared to $3.46 million in 2003.