< Wall Street's Nerds: The World's Most Powerful Trading Executives

17. John Mackay (Mack) Gill
Chief Executive Officer
MillenniumIT – London Stock Exchange Group
Last year: 18

Market technology providers routinely push the envelope in the rush to execute trades in the smallest possible fraction of a second. The 800-employee, Sri Lanka–based MillenniumIT, which London Stock Exchange Group acquired in 2009 and has been headed by John Mackay (Mack) Gill since 2013, developed one of the world's fastest exchange platforms for the LSE and has more than 40 client sites around the world using its systems. It ensures extremely low latency by deploying field-programmable gate array (FPGA) hardware in operations such as the LSE Group Ticker Plant.

But high-performance technologies aren't just for the front end of the transaction cycle. With the Millennium PostTrade clearing, settlement, and depository platform, the company relies on graphics processing units (GPUs) to deliver real-time, cross-asset analytic and risk management capabilities. Having completed a sizable installation of PostTrade last year at the Singapore Exchange, MillenniumIT is taking it up a notch with the next-generation platform now in progress for the LSEG-controlled clearinghouse LCH. "Real-time capabilities will be extended to stress testing, backtesting and member-driven 'what if' scenarios, providing a comprehensive and flexible real-time enterprisewide risk management framework," LSEG said in an announcement last fall. "Clearinghouses are systemically important entities that cut across many financial institutions," notes Gill, 47, who spent 19 years with various units of SunGard Data Systems before becoming CEO of MillenniumIT. "Improved analytics in real time, with enhanced margining and netting capabilities, are important tools for central counterparties such as LCH."

 
The 2017 Trading Tech 40

1. Richard Prager BlackRock 2. Chris Isaacson Bats Global Markets Model Portfolios to Deliver Alternative Asset Exposure Sponsored by BlackRock April 29, 2025 3. Bradley Peterson Nasdaq 4. Brad Levy MarkitSERV 5. Dan Keegan Citi

6. Glenn Lesko Bloomberg Tradebook 7. Bryan Durkin CME Group 8. Mayur Kapani Intercontinental Exchange 9. Mike Blum KCG Holdings 10. Raj Mahajan Goldman Sachs Group

11. Ronald DePoalo Fidelity Institutional 12. Nick Themelis MarketAxess Holdings 13. Jenny Knott NEX Optimisation 14. Billy Hult Tradeweb Markets 15. Rob Park IEX Group

16. Bill Chow & Richard Leung Hong Kong Exchanges and Clearing 17. John Mackay (Mack) Gill MillenniumIT 18. Paul Hamill Citadel Securities 19. Eric Noll Convergex 20. Veronica Augustsson Cinnober Financial Technology

21. Tyler Moeller & Joshua Walsky Broadway Technology 22. Alasdair Haynes Aquis Exchange 23. Gaurav Suri Arcesium 24. Manoj Narang Mana Partners 25. Michael Chin & Neill Penney Thomson Reuters

26. Robert Sloan S3 Partners 27. Anton Katz & Stephen Mock AQR Capital Management 28. Donal Byrne Corvil 29. Stu Taylor Algomi 30. Alfred Eskandar Portware

31. Steven Randich Financial Industry Regulatory Authority 32. R. Cromwell Coulson OTC Markets Group 33. Peter Maragos Dash Financial 34. John Fawcett Quantopian 35. Donald Ross III PDQ Enterprises

36. Jennifer Nayar Vela Trading Technologies 37. Dan Raju Tradier 38. Susan Estes OpenDoor Trading 39. David Mercer LMAX Exchange 40. Oki Matsumoto Monex Group