Picking up nickels in front of steamrollers

When I was growing up in the trading world, high Sharpe ratio was the holy grail. People kept forgetting the possibility of "black swan" events, only recently popularized by Nassim Taleb, which can wipe out years of steady gains in one disastrous stroke. (For a fascinating interview of Taleb by the famous Malcolm Gladwell, see this old New Yorker article. It includes a contrast with Victor Niederhoffer's trading style, plus a rare close-up view of the painful daily operations of Taleb's hedge fund.)

Now, however, the pendulum seems to have swung a little too far in the other direction. Whenever I mention a high Sharpe-ratio strategy to some experienced investor, I am often confronted with dark musings of "picking up nickels in front of steamrollers", as if all high Sharpe-ratio strategies consist of shorting out-of-the-money call options.

But many high Sharpe-ratio strategies are not akin to shorting out-of-the-money calls. My favorite example is that of short-term mean-reverting strategies. These strategies not only provide consistent small gains under normal market conditions, but in contrast to shorting calls, they make out-size gains especially when disasters struck. Indeed, they give us the best of both worlds. (Proof? Just backtest any short-term mean-reverting strategies over 2008 data.) How can that be?

There are multiple reasons why short-term mean-reverting strategies have such delightful properties:

1. Typically, we enter into positions only after the disaster has struck, not before.
   
2. If you believe a certain market is mean-reverting, and your strategy buy low and sell high, then of course you will make much more money when the market is abnormally depressed.
3. Even in the rare occasion when the market does not mean-revert after a disaster, the market is unlikely to go down much further during the short time period when we are holding the position.

"Short-term" is indeed the key to the success of these strategies. In contrast to the LTCM debacle, where they would keep piling on to a losing position day after day hoping it would mean-revert some day, short-term traders liquidate their positions at the end of a fixed time period, whether they win or lose. This greatly limits the possibility of ruin and leaves our equity intact to fight another day in the statistical game.

So, call me old-fashioned, but I still love high Sharpe-ratio strategies.

In praise of ETF's

I have learned some years ago that ETF's are strange and wonderful creatures. Simple, long-only mean-reverting strategies that work very well on ETF's, won't work on their component stocks. (Check out a nice collection of these strategies in Larry Connors' book "High Probability ETF Trading". He has also packaged these strategies into a single indicator, the ETF Power Ratings, on tradingmarkets.com.) Simple pair trading strategies like the one I discussed in my book, also work much more poorly on stocks than on ETF's. Why is that?

Well, one obvious reason is that, as Larry mentioned in his book, ETF's are not likely to go bankrupt (with the notable exception of the triple-leveraged ETF's, as I explained previously), because a whole sector or country is not likely to go bankrupt. So you can pretty much count on mean-reversion if you are on the long side.

Another obvious reason is that though there are news which will affect the valuation of a whole sector or country, these aren't as frequent or as devastating as news affecting individual stocks. And believe me, news is the biggest enemy of mean-reversion.

But finally, I believe that the capital weightings of the component stocks also play a part in promoting mean-reversion. Typically, weighting of a component stock increases with its market capitalization, though not necessarily linearly. Perhaps large-cap stocks are more prone to mean-reversion than small-cap stocks? But more intriguingly, can we not construct a basket of stocks, with custom-designed weightings, with the objective of optimizing its short-term mean-reversion property? I (and others before me) have done something similar in constructing a basket of stocks that cointegrate best with an index. Can we not construct a basket that is simply stationary (with perhaps a constant drift)?

Now, perhaps you will agree with me that ETF's are strange and wonderful creatures.

The best environment for quantitative trading

Let me talk about a topic that is far more mundane than the usual high-brow theoretical discussions of strategies and algorithms, but that has no less long-term impact on the bottom line: what is the best office environment for research and execution of quantitative trading strategies?

I have worked in different office environments before, so I feel qualified to offer an informed opinion.

At Morgan Stanley, I huddled over a desk that is semi-partitioned from the rest of the office: nobody could see or bother me unless I or they stood up. At Credit Suisse, I shared an office with 2 other prop trading colleagues, one of whom was prone to freely sharing his opinion on various current affairs with his officemates. (On the other hand, he complained my biting an apple for lunch was too loud for him.) At Maple, a hedge fund in New Jersey, I shared an office with about 100 other colleagues on the trading floor, many of whom were prone to same opinion-sharing temptation.

Here at my own firm, I sit in solitude (except for my cat) in my basement office, my beloved classical FM streaming over the internet, my desktop electronically connected to my partner in our Chicago office, our trading servers at Amazon and elsewhere, and other clients and partners around the world, but unmolested throughout the day unless I voluntarily pick up the phone or answer an email or instant message.

Can you guess which environment is the one I find the most productive? Which one has the least stress? And which one contributes most to the bottom line of my employers/partners/clients?

(Hint 1: read Timothy Ferriss' book The 4-Hour Workweek. This guy checks his email only once a week.)

(Hint 2: my trading Sharpe ratio went from negative to >7.)

P.S. I look forward to meeting some of you at the Automated Trading Conference in London this Friday (my talk will start at 0900), and others at my pairs trading workshop on the preceding two days.

Are flash orders really so bad?

I confess I don't know much about flash orders, not being one of the Big Boys on the Street, until I read that the SEC is banning them. (For a clear diagrammatic explanation of flash orders, see here. For a refutation of some of the myths and misunderstanding surrounding flash orders, see here.)

It seems to me that flash orders can be understood as "request for liquidity" issued to various potential market makers/liquidity providers, not unlike the usual "request for quotes" (RFQ) common in other industries. They are issued when there is not enough liquidity on a specific exchange to satisfy an investor's need, and they ultimately benefit investors by lowering their transaction costs. The fact that high frequency traders are able to make lots of money by providing this liquidity is besides the point. Liquidity providers are supposed to make money by providing liquidity!

Some people, including Senator Charles Schumer and this New York Times op-ed, believe that flash orders are akin to front-running, a clearly illegal trading activity. But they are wrong. Front-running means that if you know someone is going buy a stock, you step in front of them
and buy it cheaply first, hoping to sell it to this slower buyer at a higher price. In the case of flash orders, the high frequency traders are instead selling this stock to the original investor, often at a lower price than available elsewhere and thus benefiting this investor, hoping that the prices will come down in the future after this liquidity need subsides. This is manifestly not illegal. This is what a market is built for!

Another way to understand that flash orders are not at all front running is that anybody, including you and me, are free to put in limit orders at the same price as those of the high frequency traders, way ahead of time, in a specific exchange, and become liquidity providers ourselves. You don't have to wait for a "request for liquidity" before doing so. And presumably you will reap the same benefits as the high frequency traders. You are not taking any additional risks over the HF traders either, since if no requests for liquidity ultimately arrive, you are not any worse off for wear. You cannot begrudge the profits of the HF traders just because you didn't put the limit orders in place beforehand!

Maybe there are some other angles which I miss which can convince me that flash orders are evil. But until my kind readers convince me otherwise in the comments section, I will regard this piece of legislation as another SEC attempt at demagoguery.

Can a trader be a do-gooder?

It occurs to me that the only way in which a trader can become more than a completely selfish, self-enriching, narcissistic person is to trade well enough so that you can manage other people's money and thus saving these investors from crooks and charlatans (provided you are convinced you are not a crook and charlatan yourself).

Other traders have advanced other arguments in favor of trading. But I am not convinced by them.

They say that we provide liquidity to other long-term investors who may need to liquidate their investments. But then, this applies only to mean-reversal strategies. Momentum strategies take away liquidity from the market, and in some cases exacerbating price bubbles. Certainly not something your grandma would approve.

Others argue that momentum strategies help disseminate information about companies through quick price movements. But can't we just watch Bloomberg or CNBC? Do we really need some devious insiders to convey that information to the rest of us through price movements?

No, I think that independent trading should serve only one purpose (besides short-term self-sustenance): as training and preparation to become a fund manager. Once you graduated from independent trading, you then enter into the grand contest among all fund managers to see who can best serve and protect investors' assets, (and be rewarded according to your standing in this contest.)

I know, this is the idealistic way to look at things. Serving and protecting seem to be what policemen should be doing, not traders. But as in quantitative trading, I think it helps one becomes more successful in one's activities by having a simple guiding principle or model. And it doesn't hurt that in this case, the principle would also be conscience-nourishing!

Have you traded 10,000 hours yet?

Author Malcolm Gladwell, in his fascinating bestseller "Outliers: The Story of Success", cites neurological research showing that "10,000 hours of practice is required to achieve the level of mastery associated with being a world-class expert." This seems to apply across many different types of experts, whether they are "writers, ice skaters, concert pianists, chess players ... Even Mozart ... couldn't hit his stride until he had his ten thousand hours in".

Reflecting on my own experience, I have become consistently profitable only after 4 years of actual trading (research alone doesn't count -- real money need to be at risk.) So while the number of hours may not be exactly 10,000, the order of magnitude is about right.

So if your trading has not been profitable, ask yourself this: "Have I traded 10,000 hours yet?"

Using R to Test for Cointegration

Paul Teetor, who guest-blogged here about seasonal spreads, recently wrote an article about how to test for cointegration using R. Readers who don't want to pay for a copy of Matlab should find this free alternative with similar syntax quite interesting.

Interview on backtesting

I have given a 2-part interview (here and here) on the various nuances of backtesting on tradingmarkets.com. Most of the ideas have been covered in my book, but it does serve as a summary of what I consider to be the most important issues.

For those of you who are interested, I may be giving a workshop on general techniques in backtesting in London as well, in addition to my pairs trading workshop. Additional details will be available on epchan.com at a later date.