"Our main finding is that HFTs generally trade in the opposite direction of extreme price moves, supplying liquidity to non-HFTs," Brogaard, et al., wrote. "Notably, this result is driven mainly by the price jumps that result in permanent price changes. Put differently, an average HFT firm in our sample provides liquidity to aggressive, informed traders during periods of extreme price fluctuations. As such, this firm acts to stabilize markets during periods of stress."
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Critics immediately pounced on the findings.
There were two basic holes: The data set comes from 2008-09 and is limited to trades at the Nasdaq. The exchange, which trades mostly tech stocks, provides some of the most comprehensive HFT data, which isn't saying much for an industry that operates largely in the shadows. It's also a fairly small sample: 26 HFT trading firms.
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More conspicuously, the information came before 2010's infamous "Flash Crash" that sent Wall Street reeling and the Dow Jones industrial average cascading nearly 1,000 points lower before quickly shaving its losses.
And the timing could scarcely have been worse: The report went public in late November, just days before Apple shares suffered what some experts termed its own flash crash early in Monday trading.
Eric Scott Hunsader, the Nanex founder who runs the NxCore data feed service, sent a series of tweets Monday lambasting the Brogaard report:
Brogaard did not respond to a CNBC.com request for comment.
The paper reflects multiple others he has written over the years (including this one and this one) generally defending high-speed trading, which is done through computer algorithms and happens in fractions of a second. His team's papers generally find that high-frequency firms do not bail out of the market during times of turmoil, and in fact provide a buffer and liquidity source when stress occurs.