History suggests that where the US leads Europe follows, at least in the equity markets. The theory was reiterated last week as it emerged that European regulators are for the first time looking to scrutinise a small group of hedge funds and proprietary trading firms amid concerns over their growing influence.

This came just days after US senator Charles Schumer wrote a letter to the chairman of the Securities and Exchange Commission Mary Schapiro, demanding she ban flash-trading which, he claims, gives "insiders" an advantage over "retail and institutional investors".