Unstructured Finance

Not everyone agrees that using high-speed machines to trade stocks in less time than it takes the average person to blink is a bad thing, but the people who do might be heartened by the letter a congressman sent the U.S. Securities and Exchange Commission on Friday.

Rep. Edward Markey, a Massachusetts Democrat who has waged a decades-long struggle against computerized trading sent the SEC a hint: The power to curb high-frequency trading has been within its grasp all along.

In his letter, Markey described a law he co-sponsored in 1989 to increase the agency’s power to regulate computerized trading, a precursor to HFT that employed computer programs to make trading decisions without the participation of conscious humans. The law lets the SEC “limit practices which result in extraordinary levels of volatility,” according to Markey’s citation.

Markey, nudging further, added: “If the commission simply makes a finding that the markets are currently in a period of extraordinary market volatility and that HFT is reasonably certain to engender such levels of volatility, the Commission can immediately promulgate rules that restrict or eliminate the practice.”

Do current market conditions warrant this? HFT proponents say high-speed trading reduces volatility in liquid stocks. Volatility in the stock market is the lowest it has been since 2007. But incidents like the May 2010 flash crash, a head-spinning plunge in the stock market precipitated by computers, or the glitch that nearly brought down Knight Capital last summer, could count as their own sort of volatility.

By Emily Flitter

REUTERS/Rebecca Cook

While the Securities and Exchange Commission maintains it does not need to do much to reign in the high frequency trading machines that have taken over Wall Street, a group of traders who understand how HFT firms make money—because it’s similar to the method they used to use themselves—have become vocal HFT critics. Yes, they may complain because they don’t make as much money as they used to, but they also think the machines are destabilizing the market.

Meet Dennis Dick, a prop trader in Detroit and a member of a league of stock market participants who have had to change their trading strategies now that they are no longer the fastest guns on the Street.

Dick is in the company of critics like Joe Saluzzi and Sal Arnuk, the co-founders of Themis Trading whose book, Broken Markets, details their concerns about the machines.