(Previously Ranked 16) Tom Miglis encountered a refreshing set of challenges at Citadel Investment Group when he arrived in 2001. In stark contrast with his previous IT experiences at Salomon Brothers and Bankers Trust Co., where patching together existing systems was often the rule, “we develop our own technology and are not burdened by legacy systems,” says the Citadel CIO, who turns 56 in August.

Citadel, which manages $12.3 billion in hedge funds, has expanded into fund administration and investment banking. Accordingly, Miglis has built the Chicago-based firm’s technology to adapt to its widening portfolio — for example, modifying the equity trading engine for credit and mortgage products. “Across all our business lines, technology is a key part of our competitive advantage, and we are constantly innovating in response to changing market conditions,” he says.

A recent case in point: Omnium­Access, which gives administration clients real-time access to their data and to trade ideas gleaned from a deep pool of information. “The history at Citadel is using technology to differentiate ourselves,” says Miglis.

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