The Dark (Pool) Truth About What Really Goes On In The Stock Market
Courtesy of the author, we present to our readers the following excerpt from Dark Pools: High-Speed Traders, AI Bandits, and the Threat to the Global Financial System, by Scott Patterson, author of The Quants.
In early December 2009, Haim Bodek finally solved the riddle of the stock-trading problem that was killing Trading Machines, the high-frequency firm he’d help launch in 2007. The former Goldman Sachs and UBS trader was attending a party in New York City sponsored by a computer-driven trading venue. He’d been complaining for months to the venue about all the bad trades—the runaway prices, the fees—that were bleeding his firm dry. But he’d gotten little help.
At the bar, he cornered a representative of the firm and pushed for answers. The rep asked Bodek what order types he’d been using to buy and sell stocks. Bodek told him Trading Machines used limit orders.
The rep smirked and took a sip of his drink. “You can’t use those,” he told Bodek.
“You have to use other orders. Those limit orders are going to get run over.”
“But that’s what everyone uses,” Bodek said, incredulous. “That’s what Schwab uses.”
“I know. You shouldn’t.”
As the rep started to explain undocumented features about how limit orders were treated inside the venue’s matching engine, Bodek started to scribble an order on a napkin, detailing how it worked. “You’re fucked in that case?” he said, shoving the napkin at the guy.
He scribbled another. “You’re fucked in that case?” “Yeah.”
“Are you telling me you’re fucked in every case?” “Yeah.”
“Why are you telling me this?”
“We want you to turn us back on again,” the rep replied. “You see, you don’t have a bug.”
Bodek’s jaw dropped. He’d suspected something was going on in- side the market that was killing his trades, that it wasn’t a bug, but it had been only a vague suspicion with little proof.
“I’ll show you how it works.”
The rep told Bodek about the kind of orders he should use— orders that wouldn’t get abused like the plain vanilla limit orders; orders that seemed to Bodek specifically designed to abuse the limit orders by exploiting complex loopholes in the market’s plumbing. The orders Bodek had been using were child’s play, simple declarative sentences sent to exchanges such as “Buy up to $20.” These new order types were compound sentences, with multiple clauses, virtually Faulknerian in their rambling complexity.
The end result, however, was simple: Everyday investors and even sophisticated firms like Trading Machines were buying stocks for a slightly higher price than they should, and selling for a slightly lower price and paying billions in “take” fees along the way.
The special order types that gave Bodek the most trouble—the kind the trading-venue rep told him about—allowed high-frequency traders to post orders that remained hidden at a specific price point at the front of the trading queue when the market was moving, while at the same time pushing other traders back. Even as the market ticked up and down, the order wouldn’t move. It was locked and hidden. It was dark. This got around the problem of reshuffling and rerouting. The sitting-duck limit orders, meanwhile, lost their priority in the queue when the market shifted, even as the special orders maintained their priority.
Why would the high-speed firms wish to do this? Maker-taker fees that generate billions in revenue for the speed Bots every year. By staying at the front of the queue and hidden as the market shifted, the firm could place orders that, time and again, were paid the fee. Other traders had no way of knowing that the orders were there. Over and over again, their orders stepped on the hidden trades, which acted effectively as an invisible trap that made other firms pay the “take” fee.
It was fiendishly complex. The order types were pinned to a specific price, such as $20.05, and were hidden from the rest of the market until the stock hit that price. As the orders shifted around in the queue, the trap was set and the orders pounced. In ways, the venue had created a dark pool inside the lit pool.
“You’re totally screwed unless you do that,” the rep at the bar said. Bodek was astonished—and outraged. He’d been complaining for months about the bad executions he’d been getting, and had been told nothing about the hidden properties of the order types until he’d punished the it by reducing the flow he send to it. He was certain they’d known the answer all along. But they couldn’t tell everyone—because if everyone started using the abusive order types, no one would use limit orders, the food the new order types fed on.
Bodek felt sick to his stomach. “How can you do that?” he said.
The rep laughed. “If we changed things, the high-frequency traders wouldn’t send us their orders,” he said.
Courtesy of the author, we present to our readers the following excerpt from Dark Pools: High-Speed Traders, AI Bandits, and the Threat to the Global Financial System, by Scott Patterson, author of The Quants. Part 1 can be found here.
Haim Bodek thought practically nonstop for days about what the trade-venue representative had told him that night at the New York party.
The way that the abusive order types worked made him think back to a document he’d been given by a colleague that summer as he researched what was going wrong at Trading Machines. The document was a detailed blueprint of a high-frequency method that was said to be popular in Chicago’s trading circles.
Bodek suspected that there might be a link between the order types and the strategy.
Riffling through his files, he quickly found it. While the document didn’t say which firm used the strategy, he’d been told by the colleague who’d given it to him that one of the most successful high-speed firms employed it, or something closely akin to it. Due to the sophistication of the strategy, he’d guessed from the start that it was probably written by a Plumber.
There was another giveaway that it had originated in Chicago, where Bodek had worked for several years at Hull Trading: “scalping.” To a trader, scalping didn’t mean the same thing it meant to most people—a suspicious-looking guy peddling tickets for a sporting event or rock concert outside a stadium. In trading, scalping was an age-old strategy of buying low and selling high—very quickly. It was a common practice on the floors of futures exchanges that populated the Midwest—the Kansas City Board of Trade or the Chicago Mercantile Exchange. The 0+ Scalping Strategy was apparently a futures-trading technique that had been transformed into a computer program.
Bodek started reading. Page two of the document laid out the purpose of the 0+ strategy. “Simple Goal: use market depth and our order’s priority in the Q to create scalping opportunities where the loss on any one trade is limited to ‘0’ (exclusive of commissions).”
He paused at that. Essentially, the author of the strategy was saying that its primary goal was to never lose money—the loss on any trade was “0.” In theory, this could be done through a scalping strategy. By being first in the “Q”—shorthand for the queue in which orders are stacked up, like theatergoers waiting in line for their tickets—the firm could always get the best trade at the best time.
But what happened when the firm didn’t want to buy or sell? Bodek kept reading.
“GOAL RESTATEMENT: use the market depth and our order’s priority in the Q to create scalping opportunities where the probability of a +1 tic gain on any given trade is substantially greater than the probability of a –1 tic loss on any given trade.”
Aha, Bodek thought, market depth. That was a reference to the orders behind this firm’s orders, the other theatergoers waiting in line. The 0+ trader is assuming that his firm is so fast and so skilled that it can almost always get priority in the trading queue—be the first to buy and the first to sell. The depth behind it, the other orders, is the rest of the market.
The author is saying I always want to win (or rather, I never want to lose). His probability of winning—a +1 tick—is “substantially greater” than a –1 tick loss.
The rest of the market—suckers like Trading Machines or every- day mutual funds—was insurance. Under the next heading, called SIMPLE PREMISES, the exact meaning of what insurance meant was spelled out.
“If we have sufficient depth behind our order at a given price level, then we are effectively self-insured against losing money. Why? If we get elected on our order, we could immediately exit our risk for a scratch by trading against one of the orders behind us.”
In other words, if the 0+ trader buys a stock (gets “elected”), and his algos suddenly detect that the price is likely to fall—they can see a large number of sell orders stacking up in the trading queue—he can flip and sell to the sucker standing behind him, resulting in a “scratch” (no gain and no loss). He can do this because his computer systems can “react fast enough to changing market conditions . . . to ‘always’ achieve, in the worst-case, a scratch or a cancel of our orders.”
It was the Holy Grail of trading. The 0+ trader was describing a strategy that effectively never lost. The rest of the market protected it whenever the firm’s algorithms detected the slightest chance that the market was moving against it.
It’s brilliant—and diabolical. A firm that has found a strategy that is virtually guaranteed to win on every trade has discovered a hole in the market. Trading is all about taking risk, but this author was describing a virtually riskless trade.
The situation confronting Bodek and other investors not using the 0+ strategy was challenging, to say the least. It was like driving a car down the freeway, and every time you tried to speed up, another, faster car was in front of you. No matter how many tricks you pulled, this car (a 0+ symbol stamped on its hood, of course) was always leading the pack. The only time you could get around it—when it would suddenly hit the brakes and vanish in the crowd behind you—was when a Mack truck was speeding right at you. Worse, the 0+ trader was the Mack truck!
The upshot: Regular investors, the suckers using those stupid limit orders, buy high and sell low—all the time.
The game had changed. Bodek became increasingly convinced that the stock market—the United States stock market—was rigged. Exchanges appeared to be providing mechanisms to favored clients that allowed them to circumvent Reg NMS rules in ways that abused regular investors. It was complicated, a fact that helped hide the abuses, just as giant banks used complex mortgage trades to bilk clients out of billions, in the process triggering a global financial panic in 2008. Bodek wasn’t sure if it was an outright conspiracy or simply an ecosystem that had evolved to protect a single type of organism that had become critical to the survival of the pools themselves.
Courtesy of the author, here is the last excerpt from the excellent Dark Pools: High-Speed Traders, AI Bandits, and the Threat to the Global Financial System, by Scott Patterson, author of The Quants. To read the previous excerpts, see here and here.
Haim Bodek rushed out the front door of his home, jumped in his all-black Mini Cooper, and sped to the train station in downtown Stamford, thrash metal pounding from the car’s speakers.
It was the morning of March 25, 2011, his last day on the payroll of Trading Machines. Bodek was scheduled to give a speech later that afternoon at Princeton University, at a conference called “Quant Trading: From the Flash Crash to Financial Reform.”
He was running late. He hadn’t written his speech yet, so he banged it out on his laptop on the train to Princeton.
It was hard. He wasn’t sure what to say. He’d grown so cynical about the market that he’d become convinced that massive reform was required. But he didn’t know if he should be the one to spearhead changing the rules of the game. He worried about his career, whether the new elite at the high-speed firms and exchanges who’d built the market’s digital plumbing in the past decade would attack him and make it hard if not impossible for him to build another trading operation. He had a wife and three young children to support, and he was out of a job. The role of market-reform gadfly wasn’t high on his list of priorities. But his creeping belief that the market had been hijacked kept bugging him, like a bee buzzing in his face. And it wouldn’t go away.
In his talk, Bodek went halfway in calling for major changes. He spoke about the structural issues facing the options market, the evolution of algorithmic trading, and the negative impact stock market structure changes were having on the options industry. There was no mention of toxic order types or 0+ scalping strategies. He wasn’t ready to take on the whole system—yet.
Bodek knew his complaints sounded like excuses for failure. Critics would say he couldn’t take the heat. But he was convinced there was more to it. Exchanges and high-frequency firms had been working hand in glove to design a system that gave an advantage to the speedsters. The speed traders had been working closely with the electronic pools for more than a decade, from Island to BRUT to Archipelago. They’d pushed for more speed, for more information, for new exotic order types. And the pools complied willingly.
It all added up.
In Bodek’s eyes, there was nothing implicitly wrong with what had happened—at least at first. The relationship between high-speed firms and exchanges was in ways beneficial for all investors, he thought. The Bots pushed for better execution. That made the markets better for everyone.
But a problem developed. High-frequency trading became so competitive that on a truly level playing field no one could make money operating at high volumes. Starting in 2008, there had been a frantic rush into the high-frequency gold mine at a time when nearly every other investment strategy on Wall Street was imploding. That competition was making it very hard for the firms to make a profit without using methods that Bodek viewed as seedy at best.
And so a complex system evolved to pick winners and losers. It was done through speed and exotic order types. If you didn’t know which orders to use, and when to use them, you lost nearly every time.
To Bodek, it was fundamentally unfair—it was rigged. There were too many conflicts of interest, too many shared benefits between exchanges and the traders they catered to. Only the biggest, most sophisticated, connected firms in the world could win this race.
One apparent consequence of this hypercompetitive market was its fragility. Because high-speed traders were now competing for wafer-thin profits, they’d grown incredibly pain-averse. The slightest loss was unacceptable. Better to cut and run and trade another day. The result, of course, was the Flash Crash. It was an algorithmic tragedy of the commons, in which all players, acting in their self-interest, had spawned a systemically dangerous market that could threaten the global economy.
Bodek knew he’d made mistakes. He’d wasted months trying to hunt for a bug in the code of the Machine, when the problem was actually abusive order types.
Then he’d started using the order types himself to protect his firm from the abuses. But it felt dirty. He’d become one of the bad guys. One of the tipped-off insiders. Kill or be killed. He didn’t like it, but it had become a matter of survival.
It was not how the market should work. Investors should be re- warded for their intelligence, for being able to make accurate pre- dictions and take risk—not for knowing the location of secret holes inside the plumbing (or, worse, creating the holes).
That was Bodek’s biggest complaint: The Plumbers had won.
Finally, Bodek became determined to reveal what he believed was a corrupt insiders’ game that came at the expense of everyday investors. Was it outright collusion? He didn’t have enough hard information to know for certain. But he believed the exchanges were locked in cutthroat competition, not only with one another but with the dark pools and the internalizers like Citadel and Knight. It was a dynamic that went all the way back to the late 1990s when Island, Archipelago, Instinet, and other electronic networks were engaged in a kill-or-be-killed Darwinian struggle. That struggle led to massive innovation and changes and, to be sure, benefits for nearly all investors.
But something else had changed along the way. The competition had become toxic. The exchanges’ backs were against the wall, and they’d made a deal with the devil at the expense of regular investors.
And so in the summer of 2011, he decided to explain it all to federal regulators. He hired a major law firm to help him use his understanding of toxic order types he’d gained from his exchange contacts while at Trading Machines, combined with the details of his understanding of high-frequency strategies he’d learned from the 0+ Scalping Strategy document, to lay out a road map. The road map detailed his argument that high-speed traders and exchanges had created an unfair market that was hurting nearly all investors.