The year has started well in terms of equity trading. Volumes and volatility are up, helped by uncertainty over the economy and well, just about everything. But a dark cloud looms. From algorithmic trading to direct market access, politicians and regulators are challenging established business models.

Last month, the Securities and Exchange Commission voted to propose introducing a rule that would effectively prohibit broker-dealers from providing customers with "unfiltered" or "naked" access to a trading venue. The SEC's chairman Mary Schapiro compared the practice "to giving your car keys to a friend who doesn't have a licence and letting him drive unaccompanied".