"The two men worked out how the computerised system would react to certain trading patterns – allowing them to influence the price of low-volume stocks." The k

"The two men worked out how the computerised system would react to certain trading patterns – allowing them to influence the price of low-volume stocks." The key phrase here is "influence the price". Taking the quote at face value, they deliberately tried to manipulate the market. Also, there seems to be a knee-jerk reaction to HFT in the comments to this story posted anywhere. If you just run an algo, it doesn't automatically mean you manipulate the market.