Stock exchanges are part of the plumbing of Wall Street, and the details of how they’re run have never exactly captured the public imagination. That changed with Brad Katsuyama, 38, the co-founder and chief executive officer of IEX, who brought equity market structure to the mainstream as the hero of Michael Lewis’s book Flash Boys. Katsuyama was working as a trader at the Royal Bank of Canada, helping big investors buy stock, when he noticed it was getting increasingly difficult to do so without moving the price. As he investigated, he came to the conclusion that stock exchanges weren’t always looking out for investors’ interests and the market favored high-frequency traders at the expense of long-term investors. (In Lewis’s words, the market was “rigged.”) This led Katsuyama to start IEX, an exchange with a “speed bump” designed to slow down high-frequency traders on behalf of longer-term investors. After a grueling application process full of fierce resistance, IEX’s Investors Exchange gained approval from the U.S. Securities and Exchange Commission in June. “We just wanted a chance to compete,” says Katsuyama, who spoke with Matt Levine of Bloomberg View about the nuances of market structure shortly after the exchange went live in September.

David Fuller's view

This service has posted plenty of copy on predatory high-frequency trading (HFT) over the years and Brad Katsuyama was one of the few people who actually did something about it. 

Speed bumps have slowed HFT down in some markets but it is still a problem which will not go away.  Most of the momentum moves in markets are driven mainly by HFT systems, according to insiders.

We can live with that and even benefit from it on occasion, by following three common sense guidelines: buy-low, sell-high and use leverage conservatively.