Local authorities in Belgium, France, Italy and Spain yesterday dipped into controversial territory, imposing a ban on short-selling financial stocks due to recent volatility in financial markets. So what difference has it made?

At first glance it appears that the regulators' intervention has had the desired effect: each of the four countries involved has seen the average share price of its banks rebound today, with the average share price of Italian and Spanish banks even moving into positive territory, according to Bloomberg data compiled by Financial News.