In our original Flash Crash Analysis report, we dedicated a section to an observed phenomena we termed "Quote Stuffing", in which bursts of quotes (at very high rates) with extremely unusual characteristics were observed.
As we continue to monitor the markets for evidence of Quote Stuffing and Strange Sequences (Crop Circles), we find that there are dozens if not hundreds of examples to choose from on any given day. As such, this page will be updated often with charts demonstrating this activity.
The common theme with the charts shown on this page is they are obviously all generated in code and are algorithmic. Some demonstrate bizarre price or size cycling, some demonstrate large burst of quotes in extremely short time frames and some will demonstrate both. In most cases these sequences are from a single exchange with no other exchange quoting in the same time frame...
Recently we posted a required reading analysis by Nanex in which the market trading analytics firm presented irrefutable evidence of quote stuffing by HFT algorithms in tens of stocks, in which thousands of cancelled quotes would reappear each second with a definitive periodicity and regularity, around the time of the May 6 flash crash. Aside from the fact that it is illegal to indicate a quote without a trade intent, this form of quote stuffing is in fact manipulative when conducted by HFT repeaters in specific "shapes" as it actually moves the NBBO actively higher or lower, in cases pushing the bid/offer range up to 10% higher without even one trade ever having occurred, simply by masking a big block order which other algos interpret as bid interest and pull all offers progressively or step function higher (or vice versa, although we have rarely if ever seen the walking down of a stock over the past 18 months). It is as if the HFT lobby has been given the green light by the powers that be that it is safe to activate merely the bid-size quote stuffing algorithms, and not worry: the fact that the market is so one sided in its quote stuffing patterns is sufficient reason to worry of a concerted effort to push stocks higher, initiated from the very top, and effected by not only the Primary Dealer community but by the end-market "liquidity providers." Today, courtesy of Nanex we demonstrate that this type of illegal stock manipulation continues rampant to this very day, and the SEC still fails to acknowledge that it is precisely the HFT market participants that persist in destabilizing stock prices
http://www.zerohedge.com/article/its-not-market-its-hft-crop-circle-crime-scene-further-evidence-quote-stuffing-manipulation-BATS "Batsicles". BATS price cycling through a large price range, each intermittent with a stub quote, drop it down and start over
NASDAQ "Ask Mountain". Symbol IAU. Over 56,000 quotes in 10 seconds, all with same Ask Price and the Ask Size increasing or decreasing by 1 (to almost 40,000!).