2010 flash crash

Stock indices, such as the S&P 500, Dow Jones Industrial Average and Nasdaq Composite, collapsed and rebounded very rapidly. It was also the second-largest intraday point swing (difference between intraday high and intraday low) up to that point, at 1,010.14 points. The prices of stocks, stock index futures, options and exchange-traded funds (ETFs) were volatile, thus trading volume spiked. proved to be inadequate to protect investors in the August 24, 2015, flash crash — "when the price of many ETFs appeared to come unhinged from their underlying value" Sarao began his alleged market manipulation in 2009 with commercially available trading software whose code he modified "so he could rapidly place and cancel orders automatically". In May 2014, a CFTC report concluded that high-frequency traders "did not cause the Flash Crash, but contributed to it by demanding immediacy ahead of other market participants". Some recent peer-reviewed research shows that flash crashes are not isolated occurrences, but have occurred quite often. Gao and Mizrach studied US equities over the period of 1993–2011. They show that breakdowns in market quality (such as flash crashes) have occurred in every year they examined and that, apart from the financial crisis, such problems have declined since the introduction of Reg NMS. They also show that 2010, while infamous for the flash crash, was not a year with an inordinate number of breakdowns in market quality. ==Background==

On May 6, 2010, U.S. stock markets opened and the Dow was down, and trended that way for most of the day on worries about the debt crisis in Greece. At 2:42 p.m., with the Dow down more than 300 points for the day, the equity market began to fall rapidly, dropping an additional 600 points in 5 minutes for a loss of nearly 1,000 points for the day by 2:47 p.m. Twenty minutes later, by 3:07 p.m., the market had regained most of the 600-point drop. At the time of the flash crash, in May 2010, high-frequency traders were taking advantage of unintended consequences of the consolidation of the U.S. financial regulations into Regulation NMS, designed to modernize and strengthen the United States National Market System for equity securities. The Reg NMS, promulgated and described by the United States Securities and Exchange Commission, was intended to assure that investors received the best price executions for their orders by encouraging competition in the marketplace, but created attractive new opportunities for high-frequency-traders. Activities such as spoofing, layering and front running were banned by 2015. This rule was designed to give investors the best possible price when dealing in stocks, even if that price was not on the exchange that received the order. ==Explanation==

Early theories At first, while the regulatory agencies and the United States Congress announced investigations into the crash, no specific reason for the 600-point plunge was identified. Investigators focused on a number of possible causes, including a confluence of computer-automated trades, or possibly an error by human traders. By the first weekend, regulators had discounted the possibility of trader error and focused on automated trades conducted on exchanges other than the NYSE. However, CME Group, a large futures exchange, stated that, insofar as stock index futures traded on CME Group were concerned, its investigation found no evidence for this, or that high-frequency trading played a role, and in fact concluded that automated trading had contributed to market stability during the period of the crash. Others speculate that an intermarket sweep order may have played a role in triggering the crash. Several plausible theories were put forward to explain the plunge. • The fat-finger theory: In 2010 immediately after the plunge, several reports indicated that the event may have been triggered by a fat-finger trade, an inadvertent large "sell order" for Procter & Gamble stock, inciting massive algorithmic trading orders to dump the stock; however, this theory was quickly disproved after it was determined that Procter and Gamble's decline occurred after a significant decline in the E-Mini S&P 500 futures contracts. The "fat-finger trade" hypothesis was also disproved when it was determined that existing CME Group and ICE safeguards would have prevented such an error. • Impact of high frequency traders: Regulators found that high frequency traders exacerbated price declines. Regulators determined that high frequency traders sold aggressively to eliminate their positions and withdrew from the markets in the face of uncertainty. Other theories postulate that the actions of high frequency traders (HFTs) were the underlying cause of the flash crash. One hypothesis, based on the analysis of bid–ask data by Nanex, LLC, is that HFTs send non-executable orders (orders that are outside the bid–ask spread) to exchanges in batches. Though the purpose of these orders is not publicly known, some experts speculate that their purpose is to increase noise, clog exchanges, and outwit competitors. Whatever the reasons behind the existence of these orders, this theory postulates that they exacerbated the crash by overloading the exchanges on May 6. Some have put forth the theory that high-frequency trading was actually a major factor in minimizing and reversing the flash crash. • Large directional bets: Regulators said a large E-Mini S&P 500 seller set off a chain of events triggering the Flash Crash, but did not identify the firm. Earlier, some investigators suggested that a large purchase of put options on the S&P 500 index by the hedge fund Universa Investments shortly before the crash may have been among the primary causes. Other reports have speculated that the event may have been triggered by a single sale of 75,000 E-Mini S&P 500 contracts valued at around $4 billion by the Overland Park, Kansas, firm Waddell & Reed on the Chicago Mercantile Exchange. Others suspect a movement in the U.S. Dollar to Japanese yen exchange rate. • Changes in market structure: Some market structure experts speculate that, whatever the underlying causes, equity markets are vulnerable to these sorts of events because of decentralization of trading. • Technical glitches: An analysis of trading on the exchanges during the moments immediately prior to the flash crash reveals technical glitches in the reporting of prices on the NYSE and various alternative trading systems (ATSs) that might have contributed to the drying up of liquidity. According to this theory, technical problems at the NYSE led to delays as long as five minutes in NYSE quotes being reported on the Consolidated Quotation System (CQS) with time stamps indicating that the quotes were current. However, some market participants (those with access to NYSE's own quote reporting system, OpenBook) could see both correct current NYSE quotes, as well as the delayed but apparently current CQS quotes. At the same time, there were errors in the prices of some stocks (Apple Inc., Sothebys, and some ETFs). Confused and uncertain about prices, many market participants attempted to drop out of the market by posting stub quotes (very low bids and very high offers) and, at the same time, many high-frequency trading algorithms attempted to exit the market with market orders (which were executed at the stub quotes) leading to a domino effect that resulted in the flash crash plunge. SEC/CFTC report On September 30, 2010, after almost five months of investigations led by Gregg E. Berman, the U.S. Securities and Exchange Commission (SEC) and the Commodity Futures Trading Commission (CFTC) issued a joint report titled "Findings Regarding the Market Events of May 6, 2010" identifying the sequence of events leading to the flash crash. The joint 2010 report "portrayed a market so fragmented and fragile that a single large trade could send stocks into a sudden spiral", and detailed how a large mutual fund firm selling an unusually large number of E-Mini S&P contracts first exhausted available buyers, and then how high-frequency traders (HFT) started aggressively selling, accelerating the effect of the mutual fund's selling and contributing to the sharp price declines that day. The New York Times then noted, "Automatic computerized traders on the stock market shut down as they detected the sharp rise in buying and selling". firms that usually trade with customer orders from their own inventory instead of sending those orders to exchanges, "routing 'most, if not all,' retail orders to the public markets—a flood of unusual selling pressure that sucked up more dwindling liquidity". David Leinweber, director of the Center for Innovative Financial Technology at Lawrence Berkeley National Laboratory, was invited by The Journal of Portfolio Management to write an editorial, in which he openly criticized the government's technological capabilities and inability to study today's markets. Leinweber wrote: Nanex, a leading firm specialized in the analysis of high-frequency data, also pointed out to several inconsistencies in the CFTC study: Academic research File:Flash Crash.jpg|thumb|"Order flow toxicity" (measured as CDF [VPIN]) was at historically high levels one hour prior to the flash crash As of July 2011, only one theory on the causes of the flash crash was published by a Journal Citation Reports indexed, peer-reviewed scientific journal. It was reported in 2011 that one hour before its collapse in 2010, the stock market registered the highest reading of "toxic order imbalance" in previous history. In particular, in 2011 Andersen and Bondarenko conducted a comprehensive investigation of the two main versions of VPIN used by its creators, one based on the standard tick-rule (or TR-VPIN) and the other based on Bulk Volume Classification (or BVC-VPIN). They find that the value of TR-VPIN (BVC-VPIN) one hour before the crash "was surpassed on 71 (189) preceding days, constituting 11.7% (31.2%) of the pre-crash sample". Similarly, the value of TR-VPIN (BVC-VPIN) at the start of the crash was "topped on 26 (49) preceding days, or 4.3% (8.1%) of the pre-crash sample". A study of VPIN by scientists from the Lawrence Berkeley National Laboratory cited the 2011 conclusions of Easley, Lopez de Prado and O'Hara for VPIN on S&P 500 futures The authors examined the characteristics and activities of buyers and sellers in the Flash Crash and determined that a large seller, a mutual fund firm, exhausted available fundamental buyers and then triggered a cascade of selling by intermediaries, particularly high-frequency trading firms. Like the SEC/CFTC report described earlier, the authors call this cascade of selling "hot potato trading", as high-frequency firms rapidly acquired and then liquidated positions among themselves at steadily declining prices. The authors conclude: Recent research on dynamical complex networks published in Nature Physics (2013) suggests that the 2010 Flash Crash may be an example of the "avoided transition" phenomenon in network systems with critical behavior. The 2010 Flash Crash has been cited as an early example of what legal scholar Jonathan Gropper terms the 'Synthetic Outlaw' problem: an optimizing system that technically performed as designed while producing outcomes that were prohibited in effect, exposing a structural gap between formal compliance and actual harm. Evidence of market manipulation and arrest In April 2015, Navinder Singh Sarao, a London-based point-and-click trader, was arrested for his alleged role in the flash crash. According to criminal charges brought by the United States Department of Justice, Sarao allegedly used an automated program to generate large sell orders, pushing down prices, which he then canceled to buy at the lower market prices. The Commodity Futures Trading Commission filed civil charges against Sarao. In August 2015, Sarao was released on a £50,000 bail with a full extradition hearing scheduled for September with the US Department of Justice. Sarao and his company, Nav Sarao Futures Limited, allegedly made more than $40 million in profit from trading from 2009 to 2015. During extradition proceedings he was represented by Richard Egan of Tuckers Solicitors. As of 2017 Sarao's lawyers claim that all of his assets were stolen or otherwise lost in bad investments. Sarao was released on bail, banned from trading and placed under the care of his father. Sarao pleaded guilty to one count of electronic fraud and one count of spoofing. In January 2020, he was given a sentence of one year's home confinement, with no jail time. The sentence was relatively lenient, as a result of prosecutors' emphasis on how much Sarao had cooperated with them, that he was not motivated by greed and his diagnosis of Asperger syndrome. ==Aftermath==

Stock market reaction A stock market anomaly, the major market indexes dropped by over 9% (including a roughly 7% decline in a roughly 15-minute span at approximately 2:45 p.m., on May 6, 2010) before a partial rebound. While stock markets do crash, immediate rebounds are rare. The stocks of eight major companies in the S&P 500 fell to one cent per share for a short time, including Accenture, CenterPoint Energy and Exelon; while other stocks, including Sotheby's, Apple Inc. and Hewlett-Packard, increased in value to over $100,000 in price. Procter & Gamble in particular dropped nearly 37% before rebounding, within minutes, back to near its original levels. Stocks continued to rebound in the following days, helped by a bailout package in Europe to help save the euro. The S&P 500 erased all losses within a week, but selling soon took over again and the indices reached lower depths within two weeks. Congressional hearings The NASDAQ released their timeline of the anomalies during U.S. Congressional House Subcommittee on Capital Markets and Government-Sponsored Enterprises hearings on the flash crash. According to Schapiro: The circuit breakers would only be installed to the 404 New York Stock Exchange listed S&P 500 stocks. The first circuit breakers were installed to only 5 of the S&P 500 companies on Friday, June 11, to experiment with the circuit breakers. The five stocks were EOG Resources, Genuine Parts, Harley Davidson, Ryder System and Zimmer Holdings. By Monday, June 14, 44 had them. By Tuesday, June 15, the number had grown to 223, and by Wednesday, June 16, all 404 companies had circuit breakers installed. On June 16, 2010, trading in the Washington Post Company's shares were halted for five minutes after it became the first stock to trigger the new circuit breakers. Three erroneous NYSE Arca trades were said to have been the cause of the share price jump. On May 6, the markets only broke trades that were more than 60 percent away from the reference price in a process that was not transparent to market participants. A list of 'winners' and 'losers' created by this arbitrary measure has never been made public. By establishing clear and transparent standards for breaking erroneous trades, the new rules should help provide certainty in advance as to which trades will be broken, and allow market participants to better manage their risks. In a 2011 article that appeared on the Wall Street Journal on the eve of the anniversary of the 2010 "flash crash", it was reported that high-frequency traders were then less active in the stock market. Another article in the journal said trades by high-frequency traders had decreased to 53% of stock-market trading volume, from 61% in 2009. Former Delaware senator Edward E. Kaufman and Michigan senator Carl Levin published a 2011 op-ed in The New York Times a year after the Flash Crash, sharply critical of what they perceived to be the SEC's apparent lack of action to prevent a recurrence. In 2011 high-frequency traders moved away from the stock market as there had been lower volatility and volume. The combined average daily trading volume in the New York Stock Exchange and Nasdaq Stock Market in the first four months of 2011 fell 15% from 2010, to an average of 6.3 billion shares a day. Trading activities declined throughout 2011, with April's daily average of 5.8 billion shares marking the lowest month since May 2008. Sharp movements in stock prices, which were frequent during the period from 2008 to the first half of 2010, were in a decline in the Chicago Board Options Exchange volatility index, the VIX, which fell to its lowest level in April 2011 since July 2007. In 2011 trades by high-frequency traders accounted for 28% of the total volume in the futures markets, which included currencies and commodities, an increase from 22% in 2009. However, the growth of computerized and high-frequency trading in commodities and currencies coincided with a series of "flash crashes" in those markets. The role of human market makers, who match buyers and sellers and provide liquidity to the market, was more and more played by computer programs. If those program traders pulled back from the market, then big "buy" or "sell" orders could have led to sudden, big swings. It would have increased the probability of surprise distortions, as in the equity markets, according to a professional investor. In February 2011, the sugar market took a dive of 6% in just one second. On March 1, 2011, cocoa futures prices dropped 13% in less than a minute on the Intercontinental Exchange. Cocoa plunged $450 to a low of $3,217 a metric ton before rebounding quickly. The U.S. dollar tumbled against the yen on March 16, 2011, falling 5% in minutes, one of its biggest moves ever. According to a former cocoa trader: "The electronic platform is too fast; it doesn't slow things down like humans would." By April 2015, despite support for the CAT from SEC Chair Mary Jo White and members of Congress, work to finish the project continued to face delays. == In media ==

Books • The Fear Index by Robert Harris (2011) • Flash Crash by Liam Vaughan (2020) Film • Flash Crash (Announced) • Bloomberg Quicktake: The Wild $50M Ride of the Flash Crash Trader ==References==