The author is Jonathan Brogaard of Northwestern and here is the abstract:
This paper examines the impact of high frequency traders (HFTs) on equities markets. I analyze a unique data set to study the strategies utilized by HFTs, their profitability, and their relationship with characteristics of the overall market, including liquidity, price efficiency, and volatility. I find that in my sample HFTs participate in 77% of all trades and that they tend to engage in a price-reversal strategy. I find no evidence suggesting HFTs withdraw from markets in bad times or that they engage in abnormal front-running of large non-HFTs trades. The 26 high frequency trading (HFT) firms in the sample earn approximately $3 billion in profits annually. HFTs demand liquidity for 50.4% of all trades and supply liquidity for 51.4% of all trades. HFTs tend to demand liquidity in smaller amounts, and trades before and after a HFT demanded trade occur more quickly than other trades. HFTs provide the inside quotes approximately 50% of the time. In addition if HFTs were not part of the market, the average trade of 100 shares would result in a price movement of $.013 more than it currently does, while a trade of 1000 shares would cause the price to move an additional $.056. HFTs are an integral part of the price discovery process and price efficiency. Utilizing a variety of measures introduced by Hasbrouck (1991a, 1991b, 1995), I show that HFTs trades and quotes contribute more to price discovery than do non-HFTs activity. Finally, HFT reduces volatility. By constructing a hypothetical alternative price path that removes HFTs from the market, I show that the volatility of stocks is roughly unchanged when HFT initiated trades are eliminated and significantly higher when all types of HFT trades are removed.
The paper you can find here, and I thank a loyal MR reader for the pointer.