Mark Cuban unleashes on high-frequency trading

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Billionaire Mark Cuban questioned the stock market's safety Friday, bashing perceived apathy toward high-frequency trading.

Mark Cuban is shown in an episode of “Necessary Roughness.”
Richard DuCree | USA Network | NBCU Photo Bank

In a series of tweets, the Dallas Mavericks owner and "Shark Tank" investor implied people care more about alleged wrongdoing in daily fantasy sports than financial market risks. Cuban posed the question, "do you think the stock market is safer today than it was 10 years ago?"

Cuban tweet

Cuban tweet

Cuban tweet

The entrepreneur and investor previously took to his messaging app Cyber Dust to warn about high-frequency trading in August. Cuban advised investors to be careful, as traders making high-volume computer-based bets can make moves more quickly.

Read MoreCuban takes another jab at high-frequency trading

The practice notably came under scrutiny in Michael Lewis' 2014 book "Flash Boys: A Wall Street Revolt."

Disclaimer: CNBC broadcasts repeat episodes of "Shark Tank."