Quote from savagemp5:
If you buy a pair, any pair that you think its called stat arb, then I'll ask you:
- If 1 day both products =$0, do you make or lose. If you lose $, its not an arb, and certainly not statistically at all and its a risk.
- If 1 day a major news hit 1 of the pair, does the other product move together ? If it doesn't again its not an arb, and there's risk involve.
Don't mixed up pair trading, hedging, delta one, Neutral, Spread trading with stat arb. [/QUOTE
Betting on the convergence of a Cointegrating spread is stat arb. You are betting on mean reversion because of the statistical property of the time series.
A fundamental or news event can of course come out and eliminate the cointegrating relationship between two assets. Its upto the trader to know when that has happened! Cointegration does not exist into perpetuity! When you are betting on the convergence of a spread you are betting that the cointegrating relationship will exist going forward.