Quote from Craig66:
Perhaps a better question would be how do you identify potential pairs?
First off, look at stocks in the same industry and determine if they are correlated. some good sites for this are
http://www.market-topology.com/, http://www.csidata.com/index.html and one that a lot of people have good luck with
http://pairtradefinder.com/, check out the pair trading strategy in the journal forum.
next, try to figure out their cointegration to see if their spreads move in and out of their range as they move up and dowm. the more spread volatility, the more opportunity to get in and out, either intraday or a swing timeframe. this can be determined by either looking at an intraday chart that combines the 2 stocks or comparing the pair's differential ATR by the points the spread has moved in a certain time period. the higher the number, the better.
from there, look to something like PTF (site above)to indicate which pairs have diverged a certain # of standard deviations outside of their sma and are thus, most likely to come back in. check the news to make sure there is nothing crazy going on with either of the stocks, be it earnings, upgrades/downgrades, etc.
if you have heaps of cash in your account (or leverage), then you may also scale into and out of the pairs, which requires a consideration of the fundamentals as you may be holding them a while. If you determine a bias long or short then trade it accordingly. As you may be in the trades for months, adding to them as they go against you, it is imperative that you believe in your choice (whether technical or fundamentally based) so you do not get easily shaken out of your positions. Also, with this technique, IMO, it is best if you have at least 10 pairs on at all times spread over a variety of sectors(the more, the better so it is difficult for one pair to kill your day). when to get n on these is determined by where the spread is in the range of the pair's spread over some past time period (i use 2 years, as a general rule but more or less depending on the pair). For instance, if the differential of AMTD-SCHW has had a range of -6 to 2 (with a ratio of 1:1)over the past 2 years (which it has except for the period of wack volatility last fall) and i am fundamentally long (biased towards AMTD), I would start buying the pair (buy AMTD, short SCHW) when it got to about -3 on a day when it is at least down 70% of the 20 day ATR for the pair.
this is just one of many ways to trade pairs and even the method of adding layers can be done in many ways.
let me know if you have any more specific questions or maybe we will get some input from someone else.