Then an upstart alternative trading system, IEX Group was portrayed as an anti-establishment disrupter in Michael Lewis's 2014 best-seller Flash Boys. Now it is a full-fledged exchange business — IEX obtained Securities and Exchange Commission approval last June for the Investors Exchange, which went live in August. It's still taking potshots from the equity market establishment as its market share hovers around 2 percent. A distinguishing feature, built into the infrastructure overseen by chief technology officer Rob Park, is a 350-microsecond speed bump designed to enforce the IEX ideal of a "fair, simple, and transparent stock exchange" protective of long-term investors' interests. In practice the bump prevents high frequency traders from taking advantage of fleeting delays in exchanges' price updates — known as latency arbitrage, which Park, 38, calls "an invisible tax on the investment process."
A member of the IEX founding team, led by CEO Brad Katsuyama, that came out of RBC Capital Markets, Park was previously co-founder of Quantera Financial Corp., a proprietary high frequency trading firm that specialized in statistical and machine learning algorithms. He and Katsuyama are board members of TradeWind Markets, an IEX technology spin-off that raised $9 million in funding last year to develop a blockchain-based gold marketplace.
 1. Richard Prager BlackRock  2. Chris Isaacson Bats Global Markets  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 |