A Bank of England working paper finds that aggressive buying among HFT firms usually results in a lasting change in stock prices The normal debate over high frequency trading (HFT) is whether it adds to price discovery and market liquidity, or simply puts a drag on earnings through unnecessary intermediation. But the quant crash of 2007 and the flash crash of 2010 show how correlations between automatic trading can pose a real threat to market stability, at least in extreme cases. A recent Bank of England working paper written by Evangelos Benos, James Brugler, Erik Hjalmarsson, and Filip Zikes looks…