Contrary to some people's beliefs.

Concern that American stock markets have become more susceptible to split-second crashes due to computerization isn’t supported by the data, a Securities and Exchange Commission official said. Most “mini-flash crashes,” a term sometimes applied when an individual U.S. stock briefly surges or plunges for no obvious reason, are the result of human errors, not broken software, said Gregg Berman, head of the SEC’s Office of Analytics and Research.

Scrutiny of market disruptions increased in the wake of malfunctions including the flash crash of May 2010, when the Dow Jones Industrial Average fell almost 1,000 points in minutes before rebounding. In September, the Senate Subcommittee on Securities, Insurance and Investment held hearings on the impact of computerized trading amid concern algorithmic and high-frequency strategies are contributing to investor uncertainty.

“A popular meme has emerged that, taken collectively, sudden price spikes indicate a broken market” and may be harbingers of another crash like the one in 2010, Berman said in New York today at a conference sponsored by the Securities Industry and Financial Markets Association. Critics who blame everything on electronic trading “may be looking in the wrong place,” he said. SEC staff found that swings in individual stocks are more often caused by human mistakes such as “fat finger” trades -- when a person enters the wrong number of shares to trade or some other typographical error -- or incorrectly entered limit orders, Berman said. While the errors reflect sloppiness and highlight a lack of checks, they can be fixed by better risk management and oversight, he said.

Sudden Stock Crashes Mostly Show Human Error, SEC’s Berman Says [Bloomberg]
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