The Real Problem with High-Frequency Trading

Everybody seems to be talking about Michael Lewiss new book (Flash Boys ), which has been featured on 60 Minutes and reviewed twice by the New York Times. The book is about something called high-frequency trading, which, I will admit, with some, but not too much, embarrassment, I know almost nothing about. Actually, the first time I heard of the existence of high-frequency trading was from a commenter on a post I wrote almost two years ago, about which I will have something more to say in a moment. Michael Lewiss book is a polemic against high-frequency trading, alleging that it enables high-frequency traders to rig the stock market and exploit ordinary traders. Lewis makes his case by telling the story of a group of hedge-funds that have banded together to create an alternative trading platform IEX, thereby avoiding contact with the high-frequency platforms, which, according to Lewis and the heroes of his tale, is exploiting everyone else on the stock market.

Lots of other people have weighed in on both sides, some defending high-frequency trading against Lewiss accusations, pointing out that high-frequency trading has added liquidity to the market and reduced bid-ask spreads, so that ordinary investors are made better off, not worse off, as Lewis charges, and others backing him up. Still others argue that any problems with high-frequency trading are caused by regulators, not by high-speed trading as such.

I think all of this misses the point. Lots of investors are indeed benefiting from the reduced bid-ask spreads resulting from low-cost high-frequency trading. Does that mean that high-frequency trading is a good thing? Um, not necessarily.

To see what Im getting at, lets go back to the earlier post I just mentioned. I called it Soak the Rich? Heres what I said then, discussing research by Edward Saez suggesting that marginal tax rates could be increased without reducing economic growth, an idea that, to many economists, including moi, seems counterintuitive.

Is there any way of explaining why raising top marginal rates to very high levels would not cause a loss of real income? Heres an idea. The era of low marginal tax rates in the US has been associated with a huge expansion in the US financial sector. What has been the social payoff to this expansion of finance? I am not so sure. Over a century ago, Thorstein Veblen wrote his book The Theory of the Leisure Class . followed some years later by his essay The Engineers and the Price System. He distinguished between engineers who actually make things that people use and financiers who simply make investments on behalf of the leisure class, adding no value to society. This was a vulgar distinction, premised on the unwarranted assumption that finance is unproductive simply because it generates no tangible physical product. On that criterion, Veblen would have ranked pretty low as a contributor to social welfare. Mainstream economists felt pretty comfortable dismissing Veblen because he was presuming that only physical stuff can be valuable.

However in 1971, Jack Hirshleifer, one of my great teachers at UCLA, wrote a classic article The Private and Social Value of Information and the Reward to Inventive Activity. The great insight of that article is that the private value of information, say, about what the weather will be tomorrow, is greater than its value to society. The reason is that if I know that it will rain tomorrow, I can go out today and buy lots of cheap umbrellas (suppose I live in Dallas during a drought), and then sell them all tomorrow at a much higher price than I paid for them. The example does not depend on my having a monopoly in umbrellas; I sell every umbrella that I have at the rainy-day market price for umbrellas instead of the sunny-day price. The gain to me from getting that information exceeds the gain to society, because part of my gain comes at the expense of everyone who sold me an umbrella at the sunny-day price but would not have sold to me yesterday had they known that it would rain today.

Our current overblown financial sector is largely built on people hunting, scrounging, doing whatever they possibly can, to obtain any scrap of useful information — useful, that is for anticipating a price movement that can be traded on. But the net value to society from all the resources expended on that feverish, obsessive, compulsive, all-consuming search for information is close to zero (not exactly zero, but close to zero), because the gains from obtaining slightly better information are mainly obtained at some other traders expense. There is a net gain to society from faster adjustment of prices to their equilibrium levels, and there is a gain from the increased market liquidity resulting from increased trading generated by the acquisition of new information. But those gains are second-order compared to gains that merely reflect someone elses losses. Thats why there is clearly overinvestment — perhaps massive overinvestment — in the mad quest for information.

So I am inclined to conjecture that over the last 30 years, reductions in top marginal tax rates may have provided a huge incentive to expand the financial services industry. The increasing importance of finance also seems to have been a significant factor in the increasing inequality in income distribution observed over the same period. But the net gain to society from an expanding financial sector has been minimal, resources devoted to finance being resources denied to activities that produce positive net returns to society. So if my conjecture is right — and I am not at all confident that it is, but if it is – then raising marginal tax rates could actually increase economic growth by inducing the financial sector and its evil twin the gaming sector — to release resources now being employed without generating any net social benefit.

And here is one of the comments I received to my post.

An example in your favor: the construction of a more direct fiber cable from NYC to Chicago in order to save 20-30 microseconds for HFTs for around $300mm and talk of a similar venture from London (Europe) to Tokyo for five times that amount. I am sure there are sound business reasons for the construction and use of such networks but on a society level a definition of insanity?

So there you have it, high-frequency trading is a new way for traders to exploit before their competitors can any slight and fleeting information advantage that they have expended so much effort and so many resources to acquire. In other words, with the opportunity to engage in high-frequency trading, the incentive to search for, and uncover, slight and fleeting information advantages is growing ever larger, and the waste of valuable resources in the quest for such advantages is increasing parri passu .

Felix Salmon nails this point in his review of Flash Boys. observing that Michael Lewis writes his book as a tale of good guys versus bad guys. Its true the interests of his protagonists and antagonists are diametrically opposed. But his notion, that one side is somehow better than the other, is simply asserted without proof or evidence.

You never know which side Lewis is going to pick in his books. In The Big Short. for instance, he sided with, of all people, the hedge funds who helped destroy the world by making multibillion-dollar bets against the U.S. economy in the highly complex world of mortgage-bond derivatives. And now, in Flash Boys. he sides with a small group of stock traders, funded by some of New Yorks most notorious hedge fund billionaires, who have created their own private stock exchange, IEX. Truth be told, the IEX guys are a lot more sympathetic than the guys shorting mortgages. But by creating an oppositional narrative of what he explicitly describes as good guys and bad guys, Lewis runs the risk of turning a highly complex issue into an unhelpfully simplistic morality tale.

What Lewis has done is to find a group of traders who find that their attempts to trade on their information advantages are being stymied by the trading strategies devised by high-frequency traders. Lewiss guys are certainly aggrieved. But just because they have a grievance does not make them any more admirable than the high-frequency traders. Vladimir Putin has lots of grievances, too, but those grievances dont justify his actions or his arguments. Both sides are engaged in an essentially zero-sum battle for trivial informational advantage that they can exploit at the expense of informationally disadvantaged professional traders. (All traders are sometimes informationally disadvantaged. Their goal is to be informationally advantaged often enough to turn a profit.) Lewis, channeling the story of his IEX heroes, attempts to paint average investors as the victims. but Salmon effectively punctures that self-serving pretense.

[Lewis] interviews a righteous avenger by the name of John Schwall, an IEX employee with justice on his mind:

As soon as you realize that you are not able to execute your orders because someone else is able to identify what you are trying to do and race ahead of you to the other exchanges, its over, he said. It changes your mind. He stewed on the situation; the longer he stewed, the angrier he became. It really just pissed me off, he said. That people set out in this way to make money from everyone elses retirement account. I knew who was being screwed, people like my mom and pop, and I became hell-bent on figuring out who was doing the screwing.

Schwall tells Lewis that HFT is ripping off the retirement savings of the entire country through systematic fraud, and Lewis just allows the quote to sit there, damningly, even if he would never come out and put it that way himself. After all, the fact of the matter is that of all the various actors screwing your mom and pop out of the money in their retirement account, high-frequency traders are at the very bottom of the list. If, that is, theyre on the list at all.

If your mom has a brokerage account, or a mutual fund manager, or generally entrusts her retirement savings to any kind of intermediary, then the fees charged by her broker or fund manager will dwarf any profits being skimmed from her by HFT. And if your pop invests in the market himself—if hes among those people with a TD Ameritrade or E-Trade or Schwab account, the easy kill for the high-frequency algorithms, then, in reality, he is the one big winner of the high-frequency game.

Of course, the stock market is a game with winners and losers: Every time one person is buying, another person is selling. If you sell before a stock goes up, youre a loser, but if you sell before it goes down, youre a winner. And if youre making your own decisions of what to buy and sell, and at exactly what price, then there is no room to blame anybody but yourself if you make bad decisions. The trading fees and the stock prices, for individual investors, are all completely transparent.

If youre a big investor, thats not the case. Brad Katsuyama, when he was at Royal Bank of Canada, would see thousands of shares available for sale at a certain price—but when he tried to buy them, they would suddenly disappear, and he would be forced to pay more. That was the high-frequency traders, front-running his order.

Retail investors dont run into this problem. If they see a stock available for $50.00, they can buy it at $50.00—not $50.01 or anything higher. They get exactly what they want, at exactly the price they want, which is also the best price in the market, and they get it immediately, in a way that makes big investors rather jealous.

If your mom or your pop buys or sells a stock, that order will almost certainly never make its way to any stock exchange: It will be filled by a high-frequency trading shop that is happy to pay good money for the privilege of doing so. The high-frequency traders do make money from the retail investors—but mainly they do so the old-fashioned way, just by being on the right side of the trade.

If an HFT shop simply fills every single retail order at the best price in the market, then over the course of a day, and certainly over the course of a year, it will make a decent profit. Retail investors, in aggregate, are dumb money: If you take the opposite side of their trades, youre going to do just fine. Especially when you also buy stock off them for a penny or two less than you will sell the same stock to them. Thats called NBBO—the national best bid/offer—and it simply reflects the fact that theres always a small gap between the highest price that someone is willing to buy, and the lowest price that someone is willing to sell.

Thats why HFTs love to give retail investors what they want: It turns out that retail investors are very good at making very bad decisions all on their own. Whats more, if youre an HFT seeing what retail is doing at any given moment, you can use that information to inform your stock-market trades elsewhere. So mom and pop end up making you a lot of money, without your ripping them off in the slightest.

So what we have here is a war between professional traders, the practitioners of lhaute finance. The rest of us are merely bystanders in their battle, with no particular reason to consider one side or the other as representing justice, fairness, or the common good. On the contrary, their perpetual battle for new and better mechanisms for gaining temporary informational advantage make the rest of us worse off, possibly because they are causing greater volatility in them market, though that is a suggestion made by Salmon for which there is no conclusive evidence, but by diverting productive resources into socially unproductive zero-sum activities, using valuable physical and human capital to produce temporary informational advantages with little, if any, net social value, being merely the instrumentality by which to extract wealth from others who are informationally disadvantaged.

I am not a fan of Thorstein Veblens; his celebration of engineering over finance at least partly reflected a crude misunderstanding of the operation of the price system and a failure to grasp the difference between engineering efficiency and economic efficiency. But lurking in his diatribes, there may have been some inkling that much of what financiers do is a waste of real resources in a battle over the surplus generated by the real economy. It is depressing to reflect on the fact that when more than a century ago Veblen was complaining that financiers, though less productive, were more highly remunerated than engineers, the engineers were still out there designing bridges, and railroads, and other wonders of late nineteenth and early twentieth century technology, while, now in the twenty-first century, the engineers are actually employed by the financiers to design complex high-frequency trading systems, connecting New York and Chicago with fiber-optic cable to speed up trading by fractions of a second, and designing complicated software to implement trading strategies designed to exploit socially useless informational advantages. Does that sound like progress?