Charles Schwab Corp. Chairman Charles Schwab and CEO Walt Bettinger spoke out against high-frequency trading on Thursday, calling it "a growing cancer that needs to be addressed."

"High-frequency traders are gaming the system, reaping billions in the process and undermining investor confidence in the fairness of the markets," Bettinger and Schwab said in a statement. "If confidence erodes further, the fuel of our free-enterprise system, capital formation, is at risk."

Bettinger and Schwab said the HFT system is designed to "pick the pockets of legitimate market participants."

They added that more than 95 percent HFT orders were canceled last year, an event that they said suggests that "something else besides trading is at the heart of the strategy."

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Lewis Kaufman of Thornburg Investment Management echoed their sentiments.