Research from Kirilenko et al. in the Journal of Finance in 2017 has indicated that while high-frequency trading shops (HFTs) did not initiate the well-known U.S. May 6, 2010 flash crash, the sell-off event was still exacerbated by trading algorithms operating in an unforeseen way:

“Based on our analysis, we believe that High Frequency Traders exhibit trading patterns inconsistent with the traditional definition of market making. Specifically, High Frequency Traders aggressively trade in the direction of price changes.” 

Check out the research here: