At the end of last year, we had the Hank Paulson-backed Interim Report of the Committee for Capital Markets Regulation recommending watering down Sarbanes-Oxley. I looked at that here.

Then earlier this year, New York mayor Michael Bloomberg and US Senator Charles Schumer released a report warning that New York faces a dire future because of Sarbanes-Oxley, something I have examined here.

Indeed, London mayor Ken Livingstone has argued that London's growth as a financial centre can be attributed to two words: "Sarbanes" and "Oxley".

Nice line but the picture is more complicated. As I've argued many times, I believe the changes we're seeing are more a reflection of shifts in global capital and international markets.

Backing this up is a new study from academics at The Ohio State University and the University of Toronto suggests the sweeping corporate governance changes have not resulted in an exodus of companies to London.

The study Has New York become less competitive in global markets? Evaluating foreign listing choices over time found that the premium for companies listing in the US remains unchanged but there is no premium for London listings. And Sarbanes-Oxley has had very little impact.

Why the changes then? According to the study, there are fewer companies of a certain type listing on the New York Stock Exchange.

"The fact is that listing counts have been falling in London as well as in New York,'' the authors write. "This broader phenomenon makes it difficult to explain the decrease in New York alone using an argument that New York is becoming less competitive, perhaps because of SOX and other regulatory changes. It is true that the number of listings on AIM in London has been growing dramatically since 2001, but most firms that list on AIM are small firms that would have been unlikely candidates to crosslist on the U.S. exchanges.

"The argument that the U.S. exchanges have become less competitive only makes sense if some firms that would have listed in New York in the 1990s would no longer do so. We investigate this proposition and find no support for it. The characteristics of listing firms have not significantly changed since the adoption of SOX. There is little evidence that firms have been making listing decisions differently in recent years from how they made them from 1990 to 2001. If anything has changed in the aftermath of SOX, it is that the non-listed firms have become smaller and are therefore less likely to list on the U.S. exchanges or the Main Market in London."