The Nasdaq's Totally Arbitrary "Flash Crash" Cutoff For DKing Trades Of 15% From NBBO Provides A Great Arb Opportunity

Now that the PGN crash is done and over with, we decided to look at just what shares the NASDAQ decided to DK (in other words deem invalid), and which would stay. Assuming a fair and efficient market would mean all trades should stay, and the algos that were pushing the offer all the way to $4 should eat their losses, just as those who bought at $4 should keep their profits. On the other hand, assuming the whole episode was seen as one big error, then any trades that diverged from the prevailing NBBO before the crash of around $44, should be DKed. To our astonishment, the NASDAQ picked the totally arbitrary number of 15% to set as a threshold on DKing, meaning that any trades executed above $38.10 would stay, while every trade at $38.10 and below would be cancelled. As there were thousands of shares changing hands above this cut off, we are confident that many people will be very, very pissed, especially if they sold at the last accepted price of $38.38/share (see chart below). We urge if any readers traded PGN, or know of people who sold above this threshold, or, even worse, were stopped out and now see their trades stand, to immediately i) write us and describe their situation, and ii) to contact legal counsel and sue the NASDAQ for damages for setting a completely arbitrary cut off on what the exchange deems valid HFT manipulation, as opposed to outright insane. And much more importantly for everyone else: immediately set limit buy orders at 15% below the NBBO in eacn and every stock, with a subsequent sell limit the second stocks are unhalted. This will guarantee you that each and every time there is an HFT flash crash you will make lots and lots of money, courtesy of a market so broken, now apparently even the aliens are coming to help us.