The pair trading strategy was opened in the 1980s by a group of quanta operating at Morgan Stanley. Since then, this strategy is the main one in many large investment banks and hedge funds. However, since large investors prefer not to share successful strategies with the public, pair trading has long remained unknown to the general public until the advent of the Internet. Now, with the spread of online trading, many trading strategies, including paired trading, have become available to ordinary traders.
What is paired trading?
The essence of the strategy is to find two trading instruments that have a high correlation and open counter positions on them each time the difference between their prices (taking into account the correction for the scaling factors) will exceed its average historical value by a given level. With this trade, the bet is made that the price difference will always tend to return to its average value, which means that profits will be earned at one or both positions. It is important to note that paired deals always remain neutral to the market, i.å. The general direction of the market does not affect their winnings or losses.
The pair trading strategy works well not only with stocks, but also with currencies, commodities and even options. Forex contracts for difference (CFD), which require significantly less diversion than the underlying asset, allow you to successfully use pair trading, including small investors.
How to choose couples?
The first step in developing a pair trading strategy is to search for two instruments that have a high correlation. Typically, this means that they must belong to the same industry or sector, but this is not necessary. As an example, consider the shares of two companies that have a high correlation: GM and Ford. Since both companies are American automakers, their shares tend to move together. To see this, it is enough to impose a graph of their prices on each other.
However, selecting couples, focusing only on economic analysis and fundamental indicators, is difficult and not always effective. Because, firstly, it is necessary to be an expert in this field and have a good understanding of the state of affairs of the companies in question, and secondly, even having the necessary knowledge and information, manually sort through many combinations of pairs of instruments to assess their suitability for pair trading, very laborious. In addition, relying only on fundamental considerations, it is possible to miss a lot of prospective pairs, connected by dependencies, the presence of which even an experienced analyst can not guess.
Therefore, institutional investors have long started to use in their practice various statistical methods for selecting promising pairs. The simplest and most well-known method is the calculation of pairwise correlation of instruments with the subsequent selection of pairs having a high correlation coefficient (more than 80%). Now on the Internet you can find a lot of services with already calculated correlations. For example, on the site megatrader.org there is an interactive correlation table of pairs …