Why do foreign firms really leave U.S. exchanges?

There's been a running debate as of late as to why so many foreign firms chose to delist from U.S. exchanges after the March 2007 passage of Exchange Act Rule 12h-6, which made it much easier to do so. The most popular theory, of course, has been that Sarbanes-Oxley has undermined the ability of the U.S. to maintain such listings. So once the regulatory doors were opened, a mass movement to the Pink Sheets ensued. But a recent study by three academics, two Ohio State professors and one from the University of Toronto, has debunked that theory. They looked at 59 deregistered stocks and found that most experienced significantly slower growth and lower returns than other U.S.-listed foreign firms in the years before the deregistration. What's more, there is little evidence that these firms were more harmed by Sarbox than companies that chose not to deregister. Overall, it seems that most deregistrants listed to facilitate capital formation. When that did not materialize, they left.  

For more:
- here's the study