April Fool's Day appears to have arrived early on Wall Street. Either that or a story currently doing the rounds on both sides of the Atlantic is the biggest scoop of the millennium.

The Securities and Exchange Commission, the US financial watchdog, is rumoured to be investigating 44-year-old Andrew Carlssin on insider-dealing charges after a string of high-risk deals all paid off, reputedly turning the trader's initial investment of $800 in to a $350m portfolio in the space of a few weeks. So far, so routine.