The stock market has been extremely volatile with huge downward swings and roller coaster-like gains.

This has put the practice of high-frequency trading, the rapid-fire momentum style of computer program-based trading practiced by only a few trading operations, once again in the spotlight.

These hi-freq shops can and do dominate the markets in routs like 2008, the flash crash and, most recently, the ongoing bludgeoning of stocks since July 21.

Every time there’s a rout, they are there with the lion’s share of the volume, and that’s when they make the bulk of their profits.

Unfortunately, very little is known about these secretive shops, despite that on some downward days they have accounted for the majority of US trading volumes.

Wedbush Securities, which caters to this niche, estimated that this month hi-freq traders accounted for some 75 percent of US equity trading volumes. That dwarfs all other players combined.

Hi-freq traders are notorious for flooding stock exchange systems with massive orders only to turn around and cancel them.

These orders induce panic at vulnerable times, causing more fear-based selling.

Many feel such tactics are contributing to the waterfall declines we have been seeing. It’s a gaming of the system that cost peoples lots of money. It is distortive and disruptive and has real economic consequences.

In a subculture of the market where computer trades are the norm, what high-frequency traders do, they claim, add potential liquidity.

But more needs to be done to ensure that they do not distort the stock market for their own benefit by unfairly manipulating the landscape.