Quote from MasterAtWork:
Correct.That's my own opinion.
There is no such a thing. Correlation factor is just a past historical statistic, that means, no one would bet his life on it. The correlation between the two indexes is only a flow correlation. It's a very weak one.
Thus, if for any reasons people don't think Dax as a proxy of SPX but prefer Mib, the relationship between (volatility) indexes won't last anymore. And your global position is only made by both. Hence, your prior aim to bet on the spread to reduce the risk is now a much more dangerous one.
I understand that the bet would be that the historical correlation between the two will last. Before entering a position we would have to understand why such a correlation has been observed in the past and whether the fundamental circumstances explaining the high correlation have changed.
How do we call such as strategy?