Years ago, Citadel was a straightforward operation that specialised in convertible bond arbitrage, a strategy that involves buying convertible bonds and selling the equities of a given company.

Today, this operation – headed by Ken Griffin, head of Citadel Investment Group – has evolved into a diversified, multi-headed organisation. What started as a one-trick show now encompasses everything from being a huge market-maker in equity options to running reinsurance businesses.