Pairs Trading Strategy 101: A Guide for Novice Investors

By Colin Dodds · September 08, 2023 · 9 minute read

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Pairs Trading Strategy 101: A Guide for Novice Investors

Pairs trading is a market-neutral trading tactic that allows investors to use the historical performance of stocks to place long and short bets to make big profits.

Pairs trading was first used in the mid-1980s as a way of using technical and statistical analysis as a way to find potential profits. It remained the province of Wall Street professionals until the internet opened online trading and real-time financial information to the public. Before long, there were seasoned amateur investors using pairs trades to make money, while managing their risk exposure.

What Is Pairs Trading?

Pairs trading is a day trading strategy in which an investor takes a long position and a short position in two securities that have shown a high historical correlation, but which have fallen momentarily out of sync.

The correlation between the two securities refers to the degree that two securities move in relation to one other. More specifically, correlation is a statistical measurement that measures the relationship between the historical performance of two securities.

It’s usually expressed as something called a “correlation coefficient.” This measure falls between -1.0 and +1.0, with negative 1 indicating that two securities move in exactly opposite ways. A correlation coefficient of positive one indicates that the two securities move up and down at exactly the same times under the same conditions.

What Types of Assets Are Traded in Pairs?

Numerous types of financial assets can be traded in pairs, and the list includes stocks, commodities, options, funds, and even currencies. In one sense, the asset or security at the heart of the trade is somewhat irrelevant, as traders are looking to take advantage of the difference in value (and thus, a different investment position) between the two. Again, the whole goal is to try and beat the average stock market return.

Often, though, pairs trading is discussed in relation to stocks, as that may be the asset class that most trading discussions revolve around.

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Pros and Cons of Pairs Trading

Pairs trading is something that most investors can take part in, assuming they know the risks of playing the market. That’s to say that there are pros and cons to pairs trading, and investors should review them before engaging in it.

Pros of Pairs Trading

The biggest pro to pairs trading is that there is the potential for profit, or at least bigger returns than investors may have otherwise generated by executing a different investing strategy. There’s also the potential to generate positive returns no matter what the overall market conditions are. Further, pairs trading may actually be a way to mitigate risk when investing in stocks, as there are only two trades involved, and in some ways, the mechanics of the trade setup can benefit the trader — but note that this is not to say that it’s a safe or risk-free strategy.

Cons of Pairs Trading

Cons of pairs trading include the possibility of the trading model failing due to faulty assumptions on the part of a trader — that is, historical correlation between two stocks may not mean that the correlation has continued. Traders should also know that pairs trading involves fast movements, and that there’s a chance trades may not execute at the desired time — this could stymie the strategy’s effectiveness. For traders, it may be worth looking at different stock exchanges and different investment platforms to get a sense of where the strategy may be the most effective.

It may also be helpful to understand the concept of stock volume in order to have a better chance of success with the strategy.

Pairs Trading Example

In a pairs trade, an investor will look for two separate securities that have a historically high correlation, but have fallen out of sync. If “stock Alpha” and “stock Beta” have historically risen and fallen in step, they’d have a very high correlation, maybe as high as positive of 0.95. But, for whatever reason, the two stocks have diverged, with Alpha racking up big gains, while Beta languished. That has knocked the short-term correlation coefficient between the two down to paltry 0.50.

This is the most common scenario for a pairs trade. In it, an investor will take a long position on stock Alpha, which has underperformed. At the same time, they’ll short stock Beta, which has outperformed. What they’re doing in a pairs trade is betting that the relationship between the two stocks will return to their historical norm, either by one security falling, the other one rising, or some combination of the two.

Pairs Trading Strategy: Market Neutral

Pairs trading is considered a “market-neutral” strategy. There are many of these strategies, which share a common aim to profit from both rising and falling security prices, while sidestepping the risks of the broader market.

Many hedge funds will employ market-neutral strategies, because they are paid based on their absolute returns. A common market-neutral trade may involve taking a 50% long and a 50% short position in one industry, sector or market. They usually do so to take advantage of pricing discrepancies within those areas. In addition to earning a return, their main goal is often to hedge out as much systematic risk as possible.

There are also market-neutral mutual funds, which can vary wildly in what they return investors, largely because there are so many market-neutral strategies, and ways to execute them. Interested investors may want to learn the fund’s particular approach to the strategy before jumping in.

How to Successfully Execute a Pairs Trade

For investors who are ready to incorporate pairs trading into their investment strategy, there are several steps they need to take in order to be successful.

Step One: Decide on Trading Criteria

The first step is to decide what securities to consider for the trade, and can be the most time-consuming in the entire process. This involves researching a vast array of possible investment pairs to find ones that have a historically high correlation coefficient but have since drifted apart. Then investors will want to build and test a model for those securities, using those results to arrive at the best possible buy-and-sell guidelines, as well as how long they intend to stay in a trade.

Step Two: Select Specific Securities

After the investor has settled on a process to select candidates for a pairs trade, it’s time to put that process into action and find securities that currently meet that criteria. Some investors may use manual research, while others prefer mathematical models. Regardless, investors need to think of how they want to use a pairs trade.

For investors who want to get in and out of a trade in a matter of hours or days, they’ll need to run their process to find possible trades on a regular basis. But investors whose trades will last for months won’t need to run their research as often.

Step Three: Execute the Trade

Once an investor has confirmed that a trade fits all their criteria, it’s time to execute the trade. With a pairs trade, there are small but important details to consider. For instance, most experienced pairs traders will execute the short side of the trade before making the long side.

Step Four: Manage the Trade

With the trade in place, the investor now has to wait and watch. This means sizing up the activity of the two securities in the trade to see if they’re approaching the criteria that would trigger one of the predetermined buy-and-sell rules. It also means watching the broader market, as well as any news that might have an impact on either security in the trade. Experienced traders will also constantly adjust the trade’s risk/return profile as markets shift and other news emerges.

Managing the trade is as important as setting it up. If a trader has a pairs trade they expect to last a month, but it reaches 50% of its profit objective in the first day after execution, what should they do? They may choose to close out of the trade that day, because the additional return isn’t worth the risk or the opportunity cost. But they also have other options. They might initiate a trailing stop loss level in the two positions as a way of locking in a portion of the profit. The decision isn’t easy, and may involve a host of other considerations.

Step Five: Close the Trade

The final step is to close the trade. But even this can come with questions and challenges, especially with trades that haven’t worked out, and whose predetermined durations are coming to an end. But it can also be the case with trades that have succeeded and are nearing their time limit. The urge to give a trade more time to turn around — or to do just a little better — has the potential to be the undoing of an otherwise successful trader.

That’s why experienced pairs traders often stress discipline as being as important as research, close monitoring and clear rules when it comes to earning consistent profits with the strategy.

History of Pairs Trading

Pairs trading is a somewhat higher-level trading strategy (though relatively simplistic at the same time), and it was actually first developed by technical analyst researchers at Morgan Stanley during the 1980s. Specifically, Nunzio Tartaglia led the charge, who ran the “quant” group at the firm.

It has since been adopted by traders and investors, big and small.

Investing With SoFi

Pairs trading is a trading strategy that involves the simultaneous purchase and sale of securities in anticipation of a price trend. The idea is that the two securities typically have shown a high historical correlation, but have fallen momentarily out of sync. The investor making the pairs trade is betting that the two stocks will return to their historical norm.

Pairs trading is merely one of many trading strategies, and like all others, it has its pros and cons. Prospective traders may benefit from a discussion with a financial professional before trying it out.

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For a limited time, opening and funding an Active Invest account gives you the opportunity to get up to $1,000 in the stock of your choice.

FAQ

Is pairs trading still profitable?

Yes, pairs trading can be profitable, assuming a trader knows what they’re doing, and the risks involved with using the strategy. As always, there’s no guarantee that it will be profitable, however.

What are the risks of pairs trading?

Risks associated with a pairs trading strategy include the possibility of the trading model failing due to faulty assumptions on the part of a trader — that is, historical correlation between two stocks may not mean that the correlation has continued. Traders should also know that pairs trading involves fast movements, and that there’s a chance trades may not execute at the desired time.

How many pairs should a beginner trade?

It may be wise for a beginner to start with a single pair, until they get the gist or hang of the strategy.


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