Q
http://www.bloombergview.com/articles/2015-04-22/why-is-spoofing-bad-
Finally, what about spoofing and the flash crash? I obviously don't think that Navinder Singh Sarao caused the flash crash. For one thing, he turned off his spoofing algorithm a few minutes before the crash. Also, as Craig Pirrong puts it, "The complaint alleges that Sarao employed the layering strategy about 250 days, meaning that he caused 250 out of the last one flash crashes." But it's certainly possible that he contributed to it. I've heard a couple of theories on that. One, which I mentioned yesterday, is that his spoofing might have interacted badly with the algorithm that Waddell & Reed -- a big fundamental investor -- was using to sell E-mini futures. This is a story of spoofing tricking fundamental investors, with bad results for everyone. Another theory, which I heard from a high-frequency trader today, is that by spoofing high-frequency traders out of $879,018 --
Sarao's alleged profits on the day of the flash crash -- he might have caused them to hit their loss limits and shut off their own trading algorithms. Without the usual market-makers to provide liquidity, the market would have been more easily spooked than usual, and it would have been a lot easier for it to produce the wrong price. Which, for a few minutes on May 6, 2010, it definitely did.
UQ